World Environmental and Water Resources Congress 2012: Crossing Boundaries

A recent publication in Ground Water (Sept-Oct., 2010) highlighted the application of capture functions in the management of groundwater, subject to the constraints on the depletion of surface water supplies. Capture maps are used for optimal location of the pumping wells, their rates of withdrawals, and their timing. The computation of capture functions, in the cited paper, is based on perturbation approach with finite differences. An alternative computational strategy for capture functions, based on the adjoint states, is proposed here and is developed for MODFLOW, a groundwater flow simulator. The new methodology is implemented for one of the examples cited in the above paper, namely that of the San Pedro Model, with over 700,000 nodes, developed by the United States Geological Survey, and compared with their results for capture functions based on their perturbation approach. The comparison shows good agreement between the two methods. The proposed adjoint formulation just uses the same computational time, as for one simulation for the heads, and thus saves computational time, relative to the perturbation approach, by a factor equal to the number of nodes in the model, which is of the order of several hundreds of thousands. Because of its immense savings in computational times, this new strategy for the capture functions makes it feasible to embed the groundwater management problem in a stochastic framework (probabilistic approach) to address the uncertainties in the groundwater model.

Sequential data assimilation methods such as Kalman filters (KF) help the modeler yield more accurate results, especially when correction approaches (like localization) are used. In this paper, the groundwater model of Najafabad Aquifer (central Iran) is used to predict water table levels. The results of the model are assumed to be true and considered as observation data for the filter. Deterministic Ensemble Kalman Filter (DEnKF, a newly released filter) assimilated observations from true run into the model with 2, 5, and 10 times of calibrated values of hydraulic conductivity. This filter was run with/without covariance localization assuming three length-scale parameters. The results showed that DEnKF with inaccurate model parameter values has greatly improved the outputs of the inaccurate model mainly in first few time steps. Localization of the filter causes a change in secondary rising trend of error and makes it a falling trend. The amount of improvement due to localization, based on length-scale parameters, was varied and showed no obvious relationship to the accuracy of the model parameters.

The Nile Delta aquifer in Egypt is one of the largest groundwater reservoirs in the world and has been severely affected by the seawater intrusion problem from the Mediterranean sea. Due to the huge exposure of the aquifer to the seawater, the seawater and the dispersion zone migrated tens of kilometers inland causing a major deterioration in the groundwater quality. In this paper, FEFLOW, a finite element model, is used to simulated the seawater intrusion problem in the Nile Delta aquifer in the areal view at the seawater level. A fine mesh with smaller elements near the boundaries and along the two River Nile branches was implemented to ensure the accurate representation of the groundwater flow and solute transport. The model was calibrated against available measurements of groundwater levels and salinity. A good agreement between the resulted dispersion zone and the observed one.

The Northern High Plains Designated Ground Water Basin in eastern Colorado was decreed in 1966. The western boundary agreed with the accepted hydrologic boundaries of the Northern High Plains aquifer (Ogallala formation) and the Republican River drainage. In decreeing the Camp Creek Designated Ground Water Basin to the west in 1968, the 1966 hydrologic boundary was arbitrarily moved east, effectively moving the Town of Akron, seven of their wells, and 25 sections of land into that designated basin. No factual data were presented to justify the change. Camp Creek drains to the South Platte River. In 2004, the Colorado Legislature created the Republican River Water Conservation District (RRWCD) to help the State comply with the Republican River Compact Settlement Agreement. The operational western boundary now (2012) used by RRWCD is that of the 1968 Northern High Plains Designated Basin. That boundary does not agree with the ground-water model boundaries that were an essential part of the Settlement Agreement.

The Atascadero Subbasin, located on the central coast of California, is a small, hydraulically separated sub-region of the Paso Robles Groundwater Basin. Three local cities own about 40 production wells in the subbasin for their water supply needs. Past studies have questioned sustainability of the subbasin as the combined pumping rate by the three cities is approaching perennial yield of the subbasin. However, the studies have been inconclusive as some areas of the subbasin have seen increase in groundwater table elevation. This work reports on a mass balance study that has been undertaken to further examine sustainability of the subbasin. Surface water and groundwater models have been developed to study the interaction between the potential recharges from the Salinas River and the deeper Paso Robles Formation based on pumping from different shallow and deep wells in the subbasin. Surface water hydrology of the subbasin was studied using HEC-HMS and Visual MODFLOW has been used to model the aquifer. Both HEC-HMS and Visual MODFLOW have been calibrated to improve simulation accuracy. HEC-HMS has been used to quantify natural recharge of the aquifer and to simulate streamflow and water levels for the Salinas River. HEC-GeoHMS has been used to delineate the watershed, create subwatersheds and river networks, and to extract inputs that are used to build HEC-HMS from land use, soil and topographic data. The water level simulated by HEC-HMS has been used as a boundary condition for the groundwater model. Different soil layers are defined to represent the Salinas River alluvium and the deeper formations. Results will elucidate the amount of water pumped from the shallow aquifer and the deep aquifers; if the shallow aquifers are hydraulically connected to the Salinas River and are pumping the underflows; spatial distribution of the groundwater levels; and overall sustainability of the subbasin under the existing pumping rates and hydrologic conditions. Upon understanding complete water balance of the subbasin, municipal and water managers will have better picture of the effects of their pumping and can design sustainable management strategies for the subbasin.

A groundwater-level monitoring network was designed for the Upper Floridan aquifer in southern Florida, U.S.A., within the boundaries of the South Florida Water Management District. The objective of the investigation was to design a groundwater monitoring network for the Upper Floridan aquifer that recommends the number and locations of monitoring wells that will provide equivalent or better quality data compared to the existing monitoring network. This was accomplished by designing a spatial distribution of wells that will improve the accuracy of groundwater-level data measured over time and reduce data estimation errors that occur when spatially interpolating between wells in the Upper Floridan aquifer. Statistical and geostatistical analyses were performed on groundwater-level data, groundwater levels were estimated in unmeasured areas by interpolation, and proposed monitoring well locations were delineated based on acceptable levels of error for groundwater levels between wells and in areas where no wells are located. Semivariograms, which illustrate spatial autocorrelation, were plotted, and a potentiometric surface map representing salinity-adjusted mean heads in the Upper Floridan aquifer based on the current monitoring network was constructed using ordinary kriging to interpolate between wells. Three hexagonal grid network designs with different cell diameters were evaluated to determine the number and locations of proposed monitoring wells along with the resulting errors that would be associated with the different proposed design networks. A hexagonal grid with wells spaced at 29,261 m was considered to be the most practical alternative based on the costs associated with installing new wells. The recommended optimum monitoring network consists of 58 new wells added to 44 existing wells, which would result in a network of 102 wells that has a prediction standard error with a mean of 1.45 m and a range from 0.07 m to 2.62 m.

The city of Kumamoto and their surrounding area are unique in that city water is 100% supported only by their abundant groundwater. Recent expansion of the urban land-use area in and around city induces the decrease of the regional groundwater resources in spite of economical water-use efforts. The local governments try to take measures to maintain stable groundwater resources for their sustainable use, new groundwater management system is proposed and regulated by the city government and the large groundwater users in the city areas support the funding system. As the most effective recharge area is to utilize abandoned paddies exists in neighboring towns outside of the city boundary depend on the local hydro-geological setting, this management system can be a typical `trans-boundary groundwater management'. This management system was introduced in 2004 and we have experienced the effect of this system during past six years through monitoring well/lake discharge data and the precise 3D groundwater flow simulation.

Creating favorable mixing conditions in aquifers has the potential to improve the efficiency of in-situ remediation of groundwater. In current practice of in-situ remediation, the treatment solution, containing chemical or biological amendments, is either drawn through the aquifer using a downgradient extraction well or left to travel with ambient groundwater flow. Neither of these scenarios provides opportunity to enlarge the interfacial area between the treatment solution and the contaminated groundwater where degradation reactions occur. By sequentially injecting or extracting clean water at multiple wells in the aquifer, the interface between the treatment solution and the contaminated groundwater can be stretched and folded to create unique geometries that provide additional surface area for reaction, thereby accelerating the treatment process. This strategy of injection and extraction is expected to be feasible for practical application since pumping rates and duration are limited as compared to other injection-extraction approaches, for example the pulsed dipole approach investigated by others. Dispersion during the sequential injection-extraction is examined using random-walk numerical simulations to compare the degree of spreading caused by this transient injection-extraction with the degree of spreading caused by the dispersion alone. Reaction is incorporated into the simulations using a probabilistic approach and evaluated to quantify the degree to which reaction rates are enhanced through the injection-extraction scheme.

Many small communities depend on groundwater sources for drinking water and they often use septic tanks for wastewater treatment and disposal. Nitrate and other pollutants leaking from poorly designed septic tank systems can percolate to the aquifers and alter quality of the groundwater. This study describes a groundwater model developed using Visual MODFLOW for an aquifer that is used as a water supply source for the communities of Beaumont and Cherry Valley, CA. The aquifer has been contaminated by nitrates leaking from septic tank systems. The model will assist in clarifying the extent of interactions between nitrate pollutants, percolation from a recently established series of artificial recharge ponds, natural groundwater recharge, and production wells. The primary objective of the study is to evaluate alternative hydraulic solutions that would limit the movement of contaminants and minimize the risk of polluting production wells. The study will identify artificial recharge scenarios that would limit movement of the nitrates so that polluted waters may be remediated in the future, rather than allowed to encroach on critical production wells or forced away from production wells to become a problem for future generations or neighboring areas. The data needed to build the model including geological logs, aquifer properties, hydrologic data, well locations, pumping schedules, water levels and septic tank density have been collected from various sources. The groundwater model is calibrated to accurately simulate observed groundwater levels and the extent of pollution corresponding to historical pumping rates, recharge rates and climate. The calibrated model is used to evaluate alternative hydraulic solutions that would localize the nitrate pollutions thus limiting impact on public welfare.

Remote sensing techniques can be used in the characterization of landscapes for assessing groundwater resources. Digital terrain analysis has been used broadly for study subsurface geology, especially analysis of topographic features and their relationship to tectonic and structural phenomena. Structural discontinuities such as faults are expressed in a DEM as a linear feature, representing the intersection of a fracture plane and land surface. Besides, lineaments, faults originate morphotectonic structures such as depressions, asymmetric slopes across valleys and ridgelines axis. There are morphological evidences of tectonics that are represented by a point feature that may have a spatial continuity due to the same origin. This could happen especially on soft rocks that do not easily record deformations. Geophysical surveys are especially appropriate for confirming the presence, extent, and orientation of geological lineaments, as well as for detecting the presence of water in the fractures. The use of 2D resistivity profiling is widespread as a tool to identify aquifer layers in sedimentary rocks and volcanic terrains and also to detect water bearing fractures The VLF method has been applied successfully to map the resistivity contrast in fractured zones. Based on the RS lineament mapping, complemented with the digital morphological analysis and geophysics, fracturing patterns were characterized for the Plateaus region of the Quito Aquifer System (QAS). The aquifer is located in the Central Inter-Andean Valley of Ecuador, a region affected by active volcanism and faulting and characterized by basins filled with series of volcanic deposits and primary and reworked sedimentary rocks. By combining our results with those from previous geological studies and hydrogeological data, the impact of topography and fracturing on the hydrogeology of the plateaus was assessed.

Understanding the interactions between surface water and groundwater is critical for effective water management and conjunctive water use planning as these are intimately linked in the hydrologic cycle. This study is the first attempt to determine the spatio-temporal patterns of the interactions between the surface water of the Red River in Hanoi, Vietnam and the groundwater of two main adjacent aquifers, the Holocene unconfined aquifer (HUA) and Pleistocene confined aquifer (PCA). In this study, an integrated surface-groundwater model was developed by coupling two commercial modeling packages: the river flow routing model (MIKE 11) and the ground flow model (MODFLOW). As for the results, this study revealed that there was very high correlation between the river water levels and HUA groundwater levels. The correlation was found decreasing not only with the distance from the river, but also from the upstream to downstream along the river. Upper parts of the river exhibited seasonal interactions of recharge and discharge between the river and aquifer, while the lower parts of the river recharged groundwater almost throughout the year.

Guinea is known for its significant and diverse natural resources, and it is so called "Scandale Geologique" ("Geological scandal"). The mining sector is one of the most significant for Guinea economy. Mining contributes around 89% of the Government income and more than 80% of Guinea's exports (Mobbs, 1997). Current mineral resources under mining operations include bauxite, gold, diamonds, and cement. Several iron ore mining projects are under development.

Water availability for humans and the environment faces increasing threats from expanding populations and potential reduction in supply due to changes in climactic patterns. In light of these threats, the need to minimize stream depletion, defined as the depletion of flows in streams and rivers caused by groundwater pumping, becomes paramount. Stream depletion associated with pumping wells has been quantified by both analytical and numerical approaches; however, methods for identifying the stream depletion caused by new wells remain inefficient and require separate simulations for each potential well location. In this work, we develop adjoint equations of a coupled groundwater and surface water system that can be solved to calculate stream depletion. We use MODFLOW with the stream package to solve the adjoint equations, and, unlike previous work, we allow the head and resulting flow in the river to change as a result of depletion. With only one simulation of the adjoint equations, stream depletion can be calculated for a well at any location in the aquifer, making it an efficient method for siting future wells. A case study is presented comparing the stream depletion calculated using adjoint methodology with that found using traditional methods.

Growing concerns of crude oil subsurface contamination from damaged oil wells or pipeline leakage require more effective treatment methods. Among various techniques, surfactant enhanced remediation has high potential practicality in treatments of different kinds of NAPL. A self-assemble surfactant could solubilize NAPLs and generate micelles; so the oil phase will be easily remediated by continuous surfactant flooding. In this paper, different surfactants, electrolyte, co-solvent, and polymer mixtures were tested to check the solubilization performance of crude oil. Several indicators were used to investigate the solubility of crude oil in various surfactant solutions. By GC analysis results, a surfactant with brand name Aerosol WA-300 was considered to have the highest solubilization concentration for crude oil. The optimal formulation with electrolyte and co-solvent was also indicated. From the bioassay test of the surfactants, it has been concluded that there are no adverse effects of the surfactant solution on the environment.

Leakage of gasoline from underground storage tanks into the subsurface poses a severe environmental problem. Surfactant Enhanced Aquifer Remediation (SEAR), which has advantages of lower cost and shorter duration time, is discussed in this paper as an emerging remediation technology. Laboratory phase behavior tests were used to determine the optimal surfactant solution (a mixture of surfactant, electrolyte and co-solvent) to remediate subsurface gasoline contamination. Winsor Type Phase Behavior of 348 surfactant solutions were used to determine the optimum surfactant solution: twelve surfactants were tested, sodium and calcium were tested as electrolyte at varying concentrations, and Sec.Bondary butyl alcohol and isopropanol were tested as co-solvents. Finally, the surfactant solution with 6% active by weight Sulfosuccinate Blend (Aerosol® LF-4), 9000 mg/l as calcium as electrolyte and 5% Sec.Bondary butyl alcohol as co-solvent was chosen for following 1-D column test, which is used to determine the amount of gasoline recovered from sand. Observed column test results showed that most (over 95%) of residual gasoline trapped in Ottawa sand was removed.

Bare nanoscale zero-valent iron (NZVI) particles and NZVI entrapped in calcium (Ca) alginate beads were tested for the remediation of selenium (Se) species in aqueous solution. The study has demonstrated that NZVI is a very effective medium for the remediation of Se. In batch studies, bare NZVI reduced Se from 34 μg/L to < 1μg/L (> 97% removal) in 3 h. The Ca-alginate entrapped NZVI achieved a slower yet effective removal (> 85% in 12 h). While the collection and disposal of spent bare NZVI were very difficult, the Ca-alginate entrapped particles were easier to be collected and disposed off. Ca-alginate entrapment appears to be a promising method for application in aqueous Se removal. Permeable reactive barriers with entrapped NZVI can be installed for groundwater remediation, and batch application method can be practiced for surface water. Experiments are underway to find out the interferences of various ions (e.g., phosphate, nitrate, ammonium) and environmental parameters (e.g., ionic strength, temperature, pH) on Se removal by NZVI.

In a well known approach to model transport in dual-permeability or dual-porosity media, the pore space is partitioned into two flow domains such as inter- and intra-aggregate pore space in aggregated soils or fractures and a rock matrix. A variety of simplifications have been made: I. simple advection-dispersion equation (ADE) with one effective flow domain, II. mobile-immobile model (MIM) with water flow only in the mobile region and solute exchange between the mobile and immobile regions, III. dual-advection dispersion equation (DADE) with different flow but equal dispersivity in both regions and solute transfer between the regions, and IV. stream-tube model (STM) with flow according to the ADE in both domains but no solute exchange between them. A benchmark numerical model was used to assess the simplifying assumptions. Use of the DADE typically leads to the smallest error while acceptable results may be obtained for the MIM for a relatively small velocity in the "slower" domain and the STM for small values of the transfer parameter α. The ADE yielded the poorest result but can be used for higher values of the rate parameter associated with Damköhler number greater than 1. Breakthrough curve data for different depths are presented for an Andisol with pronounced "bimodal" behavior. Except for the ADE, all models did a reasonable job to describe the data but especially for MIM and STM there was considerable variation in parameter values between depths. The best description was provided by the benchmark model.

One of the largest world karez water supply systems located in the Turpan oasis, Xinjiang Uyghur Autonomous Region, China is facing challenges as water demand increases and overexploitation of groundwater by deep wells. In this paper we evaluated the vitality of the ancient karez systems in various aspects in modern society by providing examples from Turpan region of China. These aspects include the historical and cultural importance, socio-economic impacts, interactions with the surrounding environment, contribution to agricultural biodiversity in arid lands, and the unique regional characteristics of karezes. The results show that the karez systems are not only economically feasible but also a sustainable water supply for irrigation and domestic uses. Furthermore, karezes have invaluable historical, cultural and social significance. In such regions, the proper conservation and maintenance of karez systems will help sustain water supplies and contribute to economic development.

During the last 20 years, water resources datasets have been compiled in the Mesilla Basin: groundwater level monitoring data across the Mesilla aquifers, piezometric measurements along three cross sections located across the Rio Grande, seepage survey of the Rio Grande reaches between Leasburg Dam in New Mexico and El Paso, Texas, and groundwater pumping in the Canutillo wellfield located northwest of El Paso. Groundwater contour level maps have been generated for three different time periods. Daily groundwater level graphs for five different years from piezometers of the cross section A-A' were evaluated. The impact of groundwater pumping was evaluated at the Canutillo well field cross section. Seepage data was reviewed to identify how gains or losses have been behaving since the beginning of surveying efforts. Overall, this study provides with fresh analysis of groundwater-surface water interactions in the basin, aimed to contribute to enhancing the understanding of surface-groundwater interactions.

Unsaturated flow modeling is made challenging by the nonlinear dependence on matric suction by both the hydraulic conductivities and the degree of saturation. This paper utilizes a particular velocity potential approach to simply Richard's equation without resorting to perturbation methods or boundary condition assumptions. Utilizing well justified approximations of typical unsaturated soil property relationships, a linear equation for three-dimensional steady state unsaturated flow is derived. Extension of the approach to describe unsteady conditions reduces the nonlinearity of the time dependence. As an example, the derived model is used to develop an analytical solution of unsaturated flow within a trench excavation. The example results are discussed; he overall model implications are presented; and avenues of further research are suggested.

Groundwater extraction from the Calera Aquifer in the State of Zacatecas, Mexico, for irrigation, urban, and industrial uses has increased over recent decades to unsustainable levels. An annual, watershed-scale water budget analysis was conducted to identify alternative water conservation and water use scenarios, and to determine their effectiveness at reducing groundwater extraction. The scenario analysis showed that even with a 10% reduction in industrial and urban water use and a 50% reduction in irrigation water the annual groundwater deficit remains above 10 [10₆ m₃/yr]. The political and socioeconomic impacts of such large reductions in water use are likely to be unacceptable. At best, a freezing of industrial and urban water use at the level of year 2010 and a 50% reduction in irrigation water use can be hoped for, which leads to an annual groundwater deficit of about 20 [10₆ m₃/yr]. This is a great improvement over the 75 [10₆ m₃/yr] groundwater deficit of year 2010, and could potentially be adopted as a target deficit that qualifies as sustainable utilization of groundwater resources. To achieve a 50% reduction in irrigation water use will likely involve a combination of higher irrigation efficiencies, introduction of low water-demand crops, reduction in number of existing irrigation wells, land conversions, deficit irrigation, and irrigation regulations. However, circumstantial evidence suggested that the annual irrigation water reported in the literature and used in the water budget analysis was a low estimate while groundwater recharge from rainfall was a high estimate. Thus, projected annual groundwater deficits are potentially larger than reported in this study.

Urban runoff and evapotranspiration (ET) are the major components of urban water cycle. The former links with the urban water use, groundwater recharge, and pollution transport. The latter reflects water loss back to atmosphere from urban water cycle, and greatly impacts the accurate estimation of other components such as the urban runoff. The two amounts are significant for quantitatively understanding distribution of urban water cycle, preventing of pollution transport and flood, and coping with other urban environmental management problems. ET from various land use in the urban areas have different impacts on the generation and transport of urban runoff. Besides, the accuracy of ET estimation has also greatly influenced the value of urban runoff, but the course of acquiring an accurate ET value is generally complicated and time-consuming. The aim of this paper is to present the mechanism how ET impacts runoff in urban areas and Green Infrastructures, and build up the framework of calculation of urban runoff from ET estimation, based on a deep understanding of the two processes and their associations. Through an interdisciplinary literature review the perspectives from which ET in urban areas affects the urban runoff are summarized. The methods of estimation of runoff from ET amounts, and the advantages and disadvantages of each method are critically discussed. The review forms the basis for an improvement of estimation and measurements of runoff and ET in the urban area, and a better understanding the flux transport within the urban water cycle.

This paper presents design schematics and the preliminary research program for a Low Impact Development (LID) research facility to be installed at Shenzhen University, Guangdong Province, China. The research program will examine several different green roof and bioretention systems, as well as a rain garden. Different media and outlet configurations will be used to explore how these elements can be manipulated to provide the most effective hydrologic regime and pollutant removal performance. The facility is under construction as of this writing, and will be complete by the time of the conference. Initial results on media phosphorus (P) and metals removal performance and hydrologic benefits will be forthcoming in the first year of operation. Nitrogen (N) removal performance will be enhanced after plants have become established. This paper presents the overall layout of the project and the salient points to be evaluated.

Biocatalysts have not been used for sediment remediation in large scale, although they have been tested in a few pilot projects around the world. This paper presents a large scale ex-situ sediment remediation project in Guangzhou, China using an enzyme based technology followed by a solids separation, dewatering and solidification/stabilization. The goals of the project are to remediate two million tons of contaminated sediment dredged from twelve rivers in Guangzhou City, China, and to reuse the dredged materials. In addition, this technology is compared to a Portland cement based technology commonly used for sediment treatment. The system comprises an enzyme based pre-treatment oxidation ditch that processes 8000 tons of 15% solid slurry daily, a hydro-cyclone dewatering unit that takes slurry from the pretreatment and sorts the sediment into sand, silt and clay, followed by a clarifier process that settles the fine clays in a settlement pond, discharging the supernatant to receiving water. The fundamental finding was that that 85% of the solids separated and dewatered by the hydro-cyclone unit meet or exceed both "China's National Standards about the Disposal of Sludge from Municipal Wastewater Treatment Plant" and "The Control Standards for Pollutants in Sludge from Agricultural Use". The remaining 15% comprising clay was solidified and stabilized. The data showed that the enzyme addition not only degraded organic pollutants, but also improved sediment dewatering efficiency, with a low 60% moisture content in the dewatered sediment. Compared to the Portland cement-based solidification/stabilization technology, the technology has substantial advantages in terms of area required, volume reduced, odors eliminated and materials reused.

Infiltration is one of the primary functional mechanisms of green infrastructure stormwater controls, so this study explored selection and placement of embedded soil moisture, water level, and temperature sensors to monitor surface infiltration and infiltration into the underlying soil for permeable pavement systems and bioinfiltration areas at the Edison Environmental Center in Edison, NJ. In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha (1-acre) parking lot surfaced with three permeable pavement types (interlocking concrete pavers, porous concrete, and porous asphalt) and six bioinfiltration areas. The six bioinfiltration areas were designed with three different ratios of drainage area to bioinfiltration surface area (5.5:1, 11:1, and 22:1). A series of time domain reflectometers (TDRs), piezometers, and thermistors were installed at various depths in the profile in each control and in the underlying soil. A drain gauge (passive capillary lysimeter) was installed in one bioinfiltration area. The ongoing objective for this research is to develop instrument lists, placement strategies, and data analysis techniques to determine when a deviation in the control's typical performance occurs to then establish when maintenance or replacement is required. Initial results with TDRs installed in the gravel storage layer of permeable pavement systems have shown that these sensors can measure a different response when water enters the surface as direct rainfall versus rainfall combined with runoff from a contributing drainage area. This change in response represents a condition where the permeable surface upgradient of the TDRs has become clogged, so it also receives surface runoff from the contributing area.

Historically, drainage systems designed for flood management in urban areas have been focused in conveyance structures for efficient water removal. These solutions often included channelization of water bodies and elimination of natural meandering, with little consideration of the hydrologic cycle. More recently, the intense occupation of urban areas, especially the floodplains and wetlands, has put considerable stress in the drainage systems, which have grown increasingly expensive and with limited capacity in dealing with frequent floods. Current techniques to improve urban flood management are focused on restoring the watershed storage capacity and water detention through infiltration, reduction of flow velocity and increase of evapotranspiration and interception. All these processes should contribute to hold the water for slow release, contributing to mitigate floods and maintaining the water supply for the environment. Linear parks and greenways are important elements in the urban landscape, given their role in integrating the natural environment with the built one, with important functions of floodplain maintenance, recreation and wildlife corridors. This paper analyzes the contribution of an urban linear park in reducing local floods. A small urban watershed is modeled with the SWMM rainfall-runoff model to evaluate future possible scenarios with a linear park and LID elements and their effect on the resulting flood hydrograph. Results indicate that the parks are effective elements for flood control in urban areas and their design can be improved and adapted to take advantage of local conditions of land value and use, topography and vegetation.

The challenges of addressing the needs of aging water and wastewater infrastructure require new management approaches. Benefits including water savings, cost savings, and reduced wastewater production may be realized through the adoption of new integrated water management concepts such as treated wastewater effluent and/or graywater reuse, rainfall harvesting, etc. Determining which water management practices are best suited to a particular urban area can be a difficult task as costs, climate, and population characteristics vary across regions. The Integrated Urban Water Model (IUWM) has been developed by the Urban Water Center at Colorado State University to aid urban planners and utility managers in the assessment of which water management practices may prove most beneficial to their communities. These practices include: indoor conservation, irrigation conservation, wastewater treatment plant (WWTP) reuse for irrigation, graywater reuse for toilet flushing and irrigation, and stormwater capture reuse for irrigation. IUWM was applied to five cities in different climatological regions of the United States. These cities are: Fort Collins, Orlando, Philadelphia, San Diego, and Seattle. The example applications serve as both an example of how IUWM might be applied and explores the effectiveness of combinations of water management practices in different hydrologic regions. The results of the example application study confirm that hydrologic conditions impact the effectiveness of selected water management practices. Comparisons of the performance of water management practices between and within the five selected cities are made. Aside from implementation of indoor and irrigation conservation practices, graywater reuse displayed the greatest cost savings for the cities included in the study. This is a result of decreased wastewater production associated with graywater reuse.

This paper describes the calibration of runoff curve numbers for a small, developed watershed in northeast Kansas. The curve numbers were calibrated three different ways, to match the observed runoff depth, individual storm peak discharge, and observed 2, 5, 10, and 25-year peak discharges. These three calibration methods yield very different results, but all three sets of calibrated curve numbers are higher than published recommended values.

Storm-drainage design inputs such as lag times, times of concentration and rational runoff coefficients should be calibrated with local gaging data wherever possible. This paper documents the calibration of these inputs for the 170-acre Wilshire Woods watershed in the Kansas City metro area. The watershed is 33% impervious with curb-and-gutter streets, storm sewers, and a short segment of open channel. We determined the basin lag time by calibrating a simple watershed model with detailed rainfall and water-level data for 28 significant runoff events from the 13-year record. These calibrations yielded a lag time of 6 minutes and a corresponding time of concentration of 10 minutes. We performed a discharge-frequency analysis on the series of annual peak flows, and computed rational C values from the discharges and 10-minute rainfall intensities. We obtained rational C values of 0.42, 0.50, 0.52 and 0.54 for return periods of 2, 5, 10 and 25 years.

Since the passage of the Clean Water Act, wet detention ponds have been installed across the United States primarily for peak flow mitigation and sediment reduction. However, there are surprisingly minimal data on water quality benefits of these systems. Additionally, tremendous retrofitting pressure is likely to accompany state of North Carolina-implemented watershed rules associated with the Jordan Lake and Fall Lake reservoirs. Municipalities in these watersheds will be required to meet nutrient load reduction targets, necessitating urban stormwater practice retrofits for existing development. Therefore, it is imperative for many cities in central North Carolina to identify cost effective retrofits. One potential retrofit, floating wetland islands, is particularly attractive because they (1) do not require earth moving, (2) eliminate the need for additional land to be dedicated to treatment, and (3) will not detract from the required storage volume required for wet ponds (because they float). Two wet ponds in Durham, NC, were retrofitted with floating wetland islands. Prior to retrofit, both ponds had little to no vegetation growing inside them. After retrofit, one pond's surface area was comprised of 8% floating wetland islands and the second pond had 19% coverage. The two ponds were monitored in a non-retrofitted state from November 2008 to March 2010. Floating wetland islands were then installed in March-April 2010. After vegetation had established on the islands, monitoring recommenced in July 2010. Area-velocity meters and Manning's equation were used to take flow-proportional, composite water quality samples. Sixteen water quality samples were taken prior to the floating island retrofit, and twelve have been collected thus far post-retrofit. Initial results show that mean effluent concentrations of total nitrogen (TN) were reduced at one pond from 1.05 mg/L to 0.61 mg/L from pre- to post-retrofit. The other pond had relatively low effluent concentrations (0.41 mg/L and 0.43 mg/L) both pre- and post-retrofit. Mean TP effluent concentrations were reduced at both wet ponds from pre- to post-retrofit (0.17 mg/L to 0.12 mg/L and 0.11 mg/L to 0.05 mg/L. Additionally, TSS effluent concentrations at both ponds were modestly lower post-retrofit, presumably due to additional hydraulic resistance provided by the floating islands and their hanging roots, which have been measured to be approximately 0.6 m (2 ft). Initial results show some modest nutrient and sediment removal benefits from the addition of floating islands to stormwater detention ponds. Additional benefits which will be determined in the future include wetland vegetation root mass and potential improvements in benthic macroinvertebrate habitat.

Stormwater Control Measures (SCMs) have long been understood to clean and treat runoff, but these systems may provide additional ecosystem benefits not currently quantified. The main goal of this project was to determine carbon (C) sequestration potential of common roadside SCMs within the Piedmont and Coastal Plain eco-regions of North Carolina. Along highways vegetated filter strips (VFS) and vegetated swales (VS) or wetland swales (WS) work in conjunction to trap sediment bound pollutants associated with runoff from the roadway. The VFS/VS systems work well in the roadside environment since they are linear and easily border the roadway, additionally they require little maintenance. Roadside VFS/VS systems (ranging in age from 1 to 38 years) within two physiographic regions of NC were sampled to evaluate C accumulation within the soil. Based upon ArcGIS analysis, each site was identified and systematically sampled from May to July 2011. Twenty VFS/VS sites were established in the Piedmont and Coastal Plain region, respectively. An additional 20 wetland swale sites were also sampled in the Coastal Plain region, which allows a comparison between the dry swales and the WSs within the Coastal Plain. Age, regional (i.e. Piedmont versus Coastal Plain), position (sampling distance from roadway), depth, and swale characteristics (i.e. WS versus VS) effects upon C accumulation are being examined in this study.

Large-scale combined sewer systems necessitate accurate hydraulic models with a low computational requirements to depict combined sewer overflows (CSOs) in real-time. A hydraulic model is proposed that incorporates the mass and momentum equations into a series of look-up tables. Flow that enters the interceptors is routed downstream based on a hydraulic performance graph (HPG) which conserves momentum, and a volumetric performance graph (VPG) which conserves mass, established for each conduit. Weirs and sluice gates that control water distribution throughout the combined sewer system are also represented by look-up tables created off-line. During real-time computations, referencing the look-up tables is faster than computing the full equations. The model includes accurate sewer and deep tunnel components imported from Arc-GIS, and is shown to emulate EPA SWMM 5.0 dynamic wave results on a faster time scale. Calibration and timing results show that the model may be successfully applied to evaluate potential operating scenarios more quickly than SWMM.

A bacteria Total Maximum Daily Load (TMDL) assessment is in progress on Crow Creek through Cheyenne, Wyoming. The project area begins upstream of the city of Cheyenne, Wyoming, and extends to the Wyoming border with Colorado. This paper will discuss the development of a Hydrologic Simulation Program - FORTRAN (HSPF) model application to identify and address E. coli issues that are necessary for a TMDL assessment with emphasis on urban impacts. The middle section of the Crow Creek project area is represented by suburban, urban, and industrial areas in and around the city of Cheyenne. Water quality is suspected to be influenced by urban stormwater runoff, wastewater facilities, and industrial facilities. An adaptive monitoring plan was implemented to supplement historical bacteria data. To further support TMDL development, a watershed model was developed using HSPF to better characterize the critical conditions, perform the source allocation, and understand the impact alternative management/Best Management Practices (BMPs) would have in achieving the bacteria reductions prescribed by the TMDL. Three phases are involved in the development of an HSPF model application: (1) collection and development of time-series data, (2) characterization and segmentation of the watershed, and (3) calibration and validation of the model. E. coli was simulated in the model using an Event Mean Concentration (EMC) approach to apply concentrations to subsurface and overland flow.

The rapid conversion of land use to accommodate the advancement, protection, and livelihood of human populations has led to the intensification of inefficiencies and problems associated with natural resources and environmental processes. This urbanization typically results in a disconnection of the natural hydrologic system, via increased impervious surfaces, and the establishment of water conveyance systems that were designed to quickly and safely manage potable water, wastewater, and storm water (Chocat et al., 2007; U.S. EPA, 2011). Other hydrologic impacts of urbanization include flashier hydrographs, characterized by increased magnitude and timing of peak runoff, reductions in infiltration and storage capacity of the landscape, elevated concentrations of contaminants and nutrients in runoff, increased urban heat island effect, and altered channel morphologies, via erosion and sedimentation (Polaskova et al., 2006; Walsh et al., 2005; Semadeni-Davies, A., 2004; Weyrauch et al, 2010; McMichael et al., 2006).

Stormwater is a leading pollutant, which may be mitigated by stormwater control measures (SCMs) in urban, suburban and rural areas. While there have been many studies demonstrating the positive performance of SCMs, these measures are designed as individual components to meet regulatory requirements. When placed in series, SCMs can possibly prevent failure due to poor design, construction and maintenance by adding redundancy to the system. Stormwater manuals suggest placing SCMs in series, but there has been minimal research on how to accurately account for the benefits. The present research describes the design concept, construction and early-stage evaluation of a SCM treatment train that consists of a vegetated swale, bioinfiltration rain gardens and an infiltration trench. A SCM treatment train was designed to answer several questions, including quantifying the quality and quantity impact of SCMs in series, the maintenance requirements, if there is a minimum expected level for water quality, and the design recommendations.

The initial abstraction ratio (λ) used in the SCS-CN method plays an important role in calculation of runoff volume and consequently hydrograph peak. The recommended value for λ in the SCS handbook is 0.2. However, recent studies suggest that λ varies between 0.05 and 0.2, closer to the lower bound. Yet, the SCS recommended value of 0.2 is still being widely used in many hydrologic models. In this study, we explored the effects of variation in λ on simulating urbanization impacts in a coastal Alabama watershed with HEC-HMS. The potential impacts of future development scenarios on peak flows were scrutinized for λ values of 0.2 and 0.05. Results showed that the use of λ = 0.05 provides superior results when model generated hydrographs and peak flows were compared to observed counterparts.

Land surface is generally not smooth. The existence of puddles breaks the continuity of various hydrologic features/properties. The spatial connectivity of topographic surfaces has significant influence on a series of hydrologic and geomorphologic processes and results in localized and independent hydrologic mass balance. This study centers on examining the effects of surface microtopography on hydrologic connectivity. An instantaneous-profile laser scanner is utilized to acquire highresolution DEMs of surfaces with varying microtopographic characteristics. A puddle delineation software package is used to delineate the surfaces and quantify the relationships of puddles. Particularly, both structural and functional hydrologic connectivity properties are examined. In addition, the effects of DEM resolutions on hydrologic connectivity are investigated. It is found that the approach of spatial mapping of the connected areas is capable of describing the spatial complexity of connectivity of topographic surfaces. The surfaces of different microtopographic features have unique changing patterns of normalized discharge, which provides promising information to better understand the related hydrologic processes.

Stream temperature spikes associated with urban runoff can have negative ecological impacts on coldwater streams. Several local and federal regulations now specifically target urban runoff temperature, which creates a need for practices that reduce thermal export from a catchment. Several stormwater control measures (SCMs) have been shown to buffer thermal impacts to waterways by passing water through cooler subsurface media or by reducing overall runoff volume. Because it performs these functions, permeable pavement is a promising practice for thermal mitigation. A parking lot was constructed with permeable interlocking concrete pavers (PICP) the Mountain region of North Carolina to investigate the thermal behavior of this SCM. The 239-m₂ lot was divided into three cells with varying depths and drainage configurations to also test the hydrologic and thermal effects of including internal water storage (IWS) in permeable pavement. After one year of monitoring, results showed substantial stormwater volume reductions from all permeable pavement configurations, with the most pronounced reductions (99.6% and 100%) experienced in the shallow and deep IWS cells, respectively. Consequently, thermal load export from the site was reduced by a comparable amount. Median and maximum stormwater effluent temperatures from the conventionally drained cell (78% runoff reduction) exceeded the critical trout threshold temperature of 21°C, however, outflow only occurred during 8 storm events (out of the 54 recorded). Temperature differentials between the top and bottom the PICP profiles suggest that buffering of extreme runoff temperatures can occur. Additionally, the subsoil interface never reached freezing temperatures during the winter season. These results credit the use of PICP where thermal impact to streams is of concern, particularly with the incorporation of IWS.

The time of concentration (T_c) is an important parameter for hydrologic design, analysis, and modeling. Error in the estimation of T_c will cause error in prediction of peak discharge (Q_p), resulting in an incorrect design. Overland flow T_c depends on several factors, such as rainfall intensity (i), length (L), topographic slope (S₀), and flow resistance (n). Generally, Tc has an inverse relation to S₀. For the areas with very small or zero S₀, use of such small values for S₀ in traditional methods (empirical equations) for estimating T_c can produce very large values of T_c that seem to be unrealistic and incorrect. This study was conducted to identify a lower slope bound (S_LB) for the use of traditional equations in determination of T_c and to propose the use of an alternate method for the determination of T_c on low-slope planes. The diffusion hydrodynamic model (DHM) was validated using data collected from published studies and field data collected in this study, including observed rainfall hyetographs and runoff hydrographs for 27 rainfall events for watersheds with relatively low-slope. After model validation, DHM was used to generate parametric relations between T_c and its explanatory variables (rainfall intensity, length, slope and resistance to flow) and extend the regression model to low-slope planes.

Ditch checks are used throughout highway construction and are a critical element in the erosion and sediment control plan. The purpose of a ditch check is to reduce flow rates, thereby minimizing channel erosion. Proper installation is required for these devices to perform as intended. Auburn University's Erosion and Sediment Control Testing Facility (AU-ESCTF) was developed to evaluate ditch check devices used in the Alabama Department of Transportation's (ALDOT) erosion and sediment control design practices. A channelized flow testing facility was developed with the ASTM D7208-06 standard in mind, along with ALDOT's design practices and needs taking precedence. Testing procedures have been developed based on ASTM D7208-06 as well as ALDOT's needs regarding ditch check performance testing. This paper presents the ditch check testing setup and results of testing runs using 20" wattles. Water depths and flow velocities at eight cross sections were measured and agree well with predicted results from standard hydraulics equations. Changes in flow velocities and energy gradient lines were used to evaluate and assess channel erosion within the ponding and discharge zones of the ditch check. Various installation practices of ditch checks and their performances (e.g., local erosions in the channel and after ditch check) are discussed.

Bridges typically drain through scuppers directly to streams or estuaries below, potentially resulting in degradation of surface water quality. The North Carolina General Assembly enacted Session Law 2008-107 in July 2008, which required the N.C. Department of Transportation to study the effects of stormwater runoff from bridges over waterways. The resulting study characterized 15 bridge decks across three ecoregions of N.C. for runoff quality and quantity. Monitoring sites were located across the Piedmont, Coastal Plain, and Mountain ecoregions of NC and had differences in wearing surface, annual average daily traffic, rural vs. urban watershed, bridge deck surface area, and stream drainage areas. The goals included characterizing bridge deck pollutants of concern and determining the effects of bridge deck runoff on in-stream health. Runoff water quality and quantity were measured at 15 bridges, instream water quality and quantity at 4 sites, streambed sediment quality at 30 sites, bioassay tests at 13 sites, and biosurvey tests at 15 sites. Median EMCs for TSS, TN, TP, total petroleum hydrocarbons (TPH), total copper, total lead, and total zinc were 39 mg/L, 0.97 mg/L, 0.17 mg/L, 3.1 mg/L, 9.6 μg/L, 5.3 μg/L, and 66 μg/L, respectively. Twenty-two parameters of concern, those with maximum observed concentrations above the strictest available state or federal threshold, were identified, including: pH, TSS, TN, TP, five total heavy metals, five dissolved heavy metals, and seven semi-volatiles. The best predictor of pollutant concentration was the land-use type of the watershed (urban vs. rural). Pollutant concentrations and loads observed from bridge decks were similar to or less than those from other highway and urban runoff studies. Pollutant loads from the bridge decks for all analytes studied were less than 0.25% of the pollutant load contributed by the whole watershed, since the ratio of bridge deck area to watershed area was always small (<2%). At the 30 bridge deck sites studied for stream bed sediment quality (organic and inorganic pollutants), no significant difference was observed between upstream vs. downstream sediment quality or between downstream sediment quality from direct vs. no-direct discharge bridges. Composite samples from bridge deck stormwater runoff, in-stream stormflow, and in-stream baseflow were utilized in Ceriodaphnia dubia bioassay tests. All samples were tested at 100% concentration, and bridge deck runoff samples also were tested at dilutions of 50%, 25%, 12.5%, and 6.25%. Of 25 bridge deck runoff samples, 3 exhibited toxicity at 100% concentration due to significantly reduced reproduction in the test organism. Potential reasons for this toxicity included elevated conductivity in one sample and low hardness and pH in another sample. No toxicity was observed at lower dilutions of the bridge deck runoff, indicating the potential for toxicity would be attenuated at instream concentrations. Of 20 instream stormflow and baseflow samples, no toxicity was observed. Instream mixing and large catchment area relative to bridge deck footprints (as much as 10₆ larger) resulted in substantial dilution of bridge deck runoff at these sites. Biosurveys (benthic macroinvertebrate sampling) were conducted upstream and downstream of 12 bridges. Samples were obtained using Qual 5 methodology, and bioclassification was determined using the EPT and N.C. biotic index metrics. One study site had a biotic index change large enough to suggest a decline in water quality downstream of the bridge deck. However, bioclassification rating was never different between upstream and downstream sampling areas. When the data were evaluated en masse, runoff concentrations and pollutant loads were similar to those from other urban and transportation runoff studies. Attempts to tie stormwater runoff to reduced in-stream health (sediment quality, benthic health, aquatic toxicity) were unsuccessful; this suggests that bridge deck runoff does not have widespread effects on receiving water quality.

Lost Creek is a tributary of the Wabash River that runs through the campus of Rose-Hulman Institute of Technology (RHIT) in Terre Haute, Indiana. Urbanized landscapes can lead to increased stormwater runoff rates, elevated levels of nonpoint source pollutants being transported into streams, and increased rates of channel erosion due to augmented runoff quantities. Goals of this research were to measure the stream water quality at various locations throughout RHIT campus to characterize how runoff from the landscape may be affecting water quality along Lost Creek. As part of a baseline study for a restoration project, we monitored the physical behavior of Lost Creek to establish a depth-discharge rating curve, estimate erosion rates, and note any changes in bed sediment size distribution compared to measurements taken a year prior. We maintained a record of Lost Creek's channel geometry through cross-section and longitudinal profile surveys and found evidence of continuing bed degradation and toe erosion. We summarized water quality on a spatial and temporal basis by taking measurements of pH, temperature, dissolved oxygen, turbidity, specific conductance, and nutrient concentrations. The water quality data did not exhibit many overall spatial trends, but turbidity did show a general increasing trend when moving downstream through campus. We also found decreases in pH and increases in ammonia at sampling locations near the center of campus. Further monitoring over longer time periods will allow for better determination of how water quality in Lost Creek may be affected by campus runoff, which can work to aid in campus efforts of the city's stormwater management program.

In late August 2011, Hurricane Irene contributed to devastating floods in the northeastern United States. The flooding caused prolonged water quality degradation in area streams. The effects of tropical storms can result in power station failures, overflow of sewage treatment systems, and the diversion of untreated sewage to surface water and, consequently, the release of urban area pollution into natural streams. The degree of environmental impact varies depending on the storm path, wind speed, and the depth and duration of rainfall. Because of intense rainfall and excessive runoff volumes, the design capacities of many storm water management, water quality, and quantity control measures are exceeded, resulting in uncontrolled runoff reaching surface waters. Common pollution problems include elevated levels of nutrient loading, algal blooms, chemical pollutants, fecal microbial pollutants, and debris from damaged residential and industrial structures. The increased pollutant loadings usually decrease dissolved oxygen content and threaten fish and aquatic life as well as potable water supplies. The objective of this paper is to report water quality measurements for a number of pollutants along a selected number of streams in the Northeastern United States affected by Hurricane Irene. The effects of hydrological parameters, such as depth and duration of rainfall and excess runoff over urban areas, are highlighted through the relationships between flood flow rates and pollutant loadings for a selected number of streams. Pollutant loadings reported are: suspended solids, total nitrogen, phosphorus, and dissolved oxygen deficiency. A comparison of pollutant loadings before and after Hurricane Irene is presented through the relationship between the peak flow rates and pollutant loadings.

Many biofiltration facilities are located adjacent to paved infrastructure, which encourages their use as a snow storage location during the winter for snow removed from these pavements. This snow, which is contaminated with deicing salts, typically is allowed to infiltrate as the snow melts. The literature has documented any cases where the change in the ratio of sodium to calcium and magnesium has resulted in the dispersion of soil clays with a resultant loss in infiltration rate. In this study, two proposed soil mixtures, distinguished by their clay and organic content, have been evaluated for their loss in infiltration capacity as a function of salt load. At the end of the experiments, the actual pore size distribution was determined using the mercury intrusion porosimetry method. Interim results show the decrease in infiltration rate as a function of salt loading (pore volumes of water). However, this decrease was more rapid than indicated by other studies in the literature.

This paper will describe a demonstration project of Bioretention systems for a small residential community in the south end of Bridgeport, Connecticut. This project has the residents of Seaside Village, the City of Bridgeport and the Urban Ecology and Design Laboratory (UEDLAB) at Yale University as the primary stakeholders. This author has provided technical expertise for this project. Seaside Village is a small cluster of brick single family residences located just north of Seaside Park in Bridgeport, CT. Approximately 300 acres of this section of Bridgeport consists of filled soils on top of old tidal marshes. The filling was done in the late 1700s. Due to the flat topography of the area, many of the residences experience flooding during some rainfall events. The purpose of this project is to demonstrate the effectiveness of Bioretention systems for infiltrating stormwater runoff and to encourage their construction within Seaside Village for the roof drains from the residents. The UEDLAB also wanted to use the demonstration project to look at specific design modifications of Bioretention systems, although no specific ideas were initially presented. Soil tests conducted on the site showed varying depth of earth fill on top of marine clays with peat, which were underlain by medium to coarse sand. In some of the demonstration cells, a sand wick will be installed through the clay/peat layer to the underlying sand layer to evaluate how this can improve the infiltrative capacity of the cell. Variable ponding depths and corresponding surface areas will be used to determine the most effective combination of design modifications for use within Seaside Village. The paper will present the results of the site investigation, the design methodologies used and the final design to be used for construction.

The Total Daily Maximum Load (TMDL) set for the Inland Bays requires nonpoint source phosphorus loads to be reduced from 40 to 65% and nitrogen loads reduced from 40 to 85% in the different tributaries from baseline loads established from monitoring data collected from 1988 to 1990. The Simulator for Water Resources in Rural Basins (SWRRB) model and Soil and Water Assessment Tool (SWAT) were used to model different best management practice. The SWAT model was used to evaluate five land use/agriculture practice scenarios in the Millsboro Pond watershed of the Inland Bays Basin in southern Delaware. The evaluation of the five scenarios showed that they alone were not able to meet the TMDLs requirements as set by the State. Five cropping systems were evaluated with SWRRB. Introducing winter cover crops has a large effect on reducing nitrogen and phosphorus loads regardless of the tillage operation. The model SWRRB is limited in the BMPs that can be simulated for southern Delaware conditions.

SToRM is a component of the USGS Multi-Dimensional Surface Water Modeling System (McDonald and others, 2012). SToRM is one of a generation of recently available 2-D hydrodynamic models available without charge or for low cost. In this paper SToRM was applied to two test situations where actual measurements were available in part to test the tool itself at physical scales that differ by about an order of magnitude, and to develop the skill set necessary to use the tool for an arbitrary situation. The two cases are a 200cm wide, 1400 cm long, 100cm deep laboratory flume with 3-D velocity measuring capability and a field site during a flood event that engaged about 30 meters wide flow between cross sections located 100 meters apart. The flume geometry is far smaller than for which SToRM was intended, however after considerable iteration, the program was able to produce results that compared favorably with measured velocities in the flume. The lesson from flume modeling was that the simulation process is quite iterative. The field case study used SToRM to model a flood event for which the authors had collected actual water surface elevations by conventional post-event survey. The input discharge was estimated by conventional indirect methods. As with the flume simulation, through considerable iteration SToRM eventually produced results that were consistent with observations. The extension of the topographic survey (real data) into an elevation grid suitable for the 2D hydrodynamics software was more complicated than anticipated, and suggestions are provided to help with the diagnosis of a poor elevation grid. The other overall substantial lesson is that convergence in the software has a far different meaning than convergence in the mass-balance sense. These different connotations were not apparent in the documentation, and without an understanding of this particular issue the apparently converged results could greatly mislead the analyst. Examples from our simulations are provided along with a suggested approach for using SToRM.

The North Platte River Watershed near Casper, Wyoming, has several streams and waterbodies listed as impaired for selenium on the state of Wyoming's 303(d) list, including the North Platte River. The source of selenium in the North Platte River Watershed near Casper is the local geology that consists of cretaceous tertiary shale formations with high levels of selenium. Past assessments of selenium in the watershed have focused on the influence irrigation practices on these cretaceous shales have on selenium concentrations in the river system. The Casper Canal delivers irrigation water from Alcova Reservoir, located approximately 25 miles southwest of Casper, to approximately 24,000 acres of irrigated lands in the Casper-Alcova Irrigation District. This project, initiated in 2009 by the Wyoming Department of Environmental Quality (WDEQ), was a Total Maximum Daily Load (TMDL) project for selenium in the North Platte River and four of its major tributaries. To explain variability in the selenium data, a spatial regression approach was used to correlate watershed characteristics to selenium concentrations at several locations in the North Platte River Watershed near Casper. Possible sources were identified as the watershed characteristics with the highest correlation to selenium concentrations. This analysis expanded on an earlier U.S. Geological Survey study that applied a similar methodology of regressing watershed characteristics to predict in-stream selenium concentration. This TMDL project incorporated the regression analysis to aid in allocating the loading to various sources within the watershed and to help guide implementation in the watershed for future projects. It was found that most of the variability in selenium can be explained by the percent of irrigated land, the length of irrigation canals, and the percent of cretaceous shale in each subwatershed. Background levels of selenium from sources other than irrigation practices were also evaluated to determine the ability of the tributary streams to meet the current water-quality criteria.

This paper presents a simulation-based optimization model to perform optimal control of flood stages under complex channel geometries and sediment properties in channels and channel network of a watershed. The flood control is demonstrated by operating multiple gates to withdraw flood waters from the alluvial channels in the watershed. The optimal withdrawal hydrographs for the floodgate operations are obtained by this optimization model which contains flow and morphodynamic models to simulate hydrodynamic and morphodynamic processes. Based on the designated flood control criteria (the objective water stages), the optimal solutions for determining diversion flow rates are found by solving the nonlinear adjoint equations of the nonlinear one-dimensional Saint-Venant equations. Through study of optimal control of flows with sediment transport, it is found that the influence of morphological changes on flood control becomes critical under certain hydrological and morphological conditions, and the responses of morphology to the control actions can help select the best locations of the control facilities (i.e. floodgates).

Stormwater bacteria data are challenging to analyze for several reasons: ≤ highly variable observation levels (more so than for any other commonly monitored stormwater constituent) ≤ frequent right-censored data (very high levels can exceed the upper limit of the method being used) ≤ non-conservative behavior can cause unusual observations and storage problems during sample collection ≤ sensitive to environmental conditions (especially temperature) ≤ most analytical methods have a limited range in bacteria levels that can be quantified In addition, traditional bacteria data reporting is usually expressed as a geometric mean in order to moderate the effects of periodic very high observed bacteria levels (most bacteria standards or criteria are expressed using geometric means, for example), which hinder statistical analyses of existing information. These issues therefore hinder the types of statistical analyses that can be conducted using most stormwater bacteria data. However, many of these problems can be overcome by careful sampling and proper selection of the analytical method, as noted below. Sampling plans must consider the sampling locations appropriate for the project objectives. Bacteria sources vary greatly in urban areas, but high levels can be observed in many locations. Roof runoff water can have very high levels during summer and spring months if heavily covered by trees, due to the increased numbers of birds and squirrels that can reside above the roof surfaces. During colder months, many of these animals may migrate, hibernate, or become inactive, resulting in significantly decreased bacteria levels in the roof runoff. Soil bacteria levels can remain high in areas where urban wildlife or pets defecate, with runoff bacteria levels dependent on the amount of erosion occurring. Bacteria levels in runoff from paved areas can also be high in areas where pets are "walked." Residential areas and park pathways usually have larger bacteria levels than industrial areas, for example. Outfall stormwater samples are affected by the relative contributions of flows from the different areas which vary mostly according to rain characteristics. Therefore, an experimental design for bacteria sampling must consider these varying sources and seasonal conditions, requiring many samples over an extended period.

Combined sewer systems (CSS) are under regulatory mandate to reduce or treat combined sewer overflow (CSO) discharges in order to protect receiving waters. Under the requirements of the Clean Water Act, municipalities are responsible for developing comprehensive long-term control plans (LTCPs). These plans must identify a selected alternative, a level of control and a schedule for reducing discharges. Historically, CSO control methods included various approaches to manage the excess flows, including storage, remote treatment and conveyance to a centralized treatment plant or sewer separation. Many of the plans developed subsequent to 2007 include an approach which relies on green infrastructure and similar stormwater source controls. Green infrastructure includes practices and site-design techniques that store, infiltrate, evaporate, or detain stormwater runoff and in so doing, control the timing and volume of stormwater discharges from impervious surfaces (e.g., streets, building roofs, and parking lots) to the sewer system. In order to determine the most effective use of green infrastructure, municipalities are evaluating a number of strategies and approaches to its application. Implementation must consider site-specific issues in each community and the opportunities for cost effective implementation. An evaluation of 12 municipal programs that incorporate green infrastructure into their LTCP was performed in 2011. This paper summarizes the various approaches that municipalities used for evaluating green infrastructure. Those approaches included GIS evaluations, modeling and cost / benefit assessments.

Nowadays, water is a critical issue in developing countries. By water collection from roof of residential area, we could manage water crisis and improve supply for irrigation and non-potable water consumptions. When a rainwater harvesting system on the roof of residential buildings is simulated based on time series of daily precipitation in a given target location, the amount of supply for non-potable water demand may be determined. Design and implementation based on simulation results will lead to the enhanced effectiveness of such systems in different cities. In this paper, time series of daily precipitation in Qazvin city, Iran, was collected for the 1960 - 2008 period. Optimization of tank size for rainwater harvesting on the roof of typical residential buildings was carried out through maximization of benefit to cost ratio. According to the results obtained by modeling and optimization of the system, the tank can provide most part of the non-potable water demand while the remaining demand is met by regular water distribution system.

Numerous studies have been conducted on the performance of stormwater bio-infiltration media due to a massive number of different products spawned by the growing interest in low impact development (LID) recently. However, the effects by infiltration rate, biomedia depth and solids concentration remain unclear, which impedes a direct comparison of different biomedia products and often leads to improper design and misused employment. In this study, Sil-Co-Sil 106 (SCS 106) ground silica sand with D₅₀ of approximately 25 μm and tap water were employed to simulate suspended solids concentration (SSC) in the assessment of solids removal performance. Evaluation testing was investigated with regard to the influence of biomedia depth (12", 18", 24", and 30"), influent concentration (20, 100, and 200 mg/L), and infiltration rate (25, 50, 100, 150 and 200 in/hr). The resulting data points demonstrated clear patterns. Deeper biomedia bed yielded better removal - 89% for the shallowest biomedia depth of 12". Removals at influent concentrations of 100 and 200 mg/L were very similar, both greater than 90%. At low influent concentration of 20 mg/L, it was difficult to achieve high removal rate though effluent concentration was significantly reduced to a lower level. Removals at all the tested infiltration rates were invariably higher than 90% and lower infiltrate rate promoted better removals.

The U.S. Environmental Protection Agency is in the process of developing a nationwide standard for turbidity in construction site runoff. It is widely expected that this standard cannot be met with conventional erosion and sediment control measures; consequently, innovative practices for managing sediment on construction sites must be developed. One emerging practice is the use of polyacrylamide (PAM) to improve sediment control by promoting flocculation of particles in runoff. For this practice to be used efficiently, it is essential to understand how soil and PAM properties affect flocculation. A protocol for creating modified synthetic stormwater runoff from soil samples was developed and used on soils from six Texas construction sites. Flocculation tests were performed on these synthetic stormwaters with PAM doses from 0.03 to 10 mg/L. The polymers used ranged from anionic PAMs of 0% to 50% charge density and 0.2 to 14 Mg/mol molecular weight as well as one co-polymer. A neutral PAM and the co-polymer were found to be most effective in reducing the turbidity of all the modified synthetic stormwater below 200 NTU at doses of 10 mg/L. Hardness and electrophoretic mobility tests indicated interparticle bridging to be the bonding mechanism. The high molecular weight (HMW) anionic PAMs were effective on only two of the six modified synthetic runoffs. As the charge density of these HMW PAMs increased, their effectiveness decreased.

Combined sewer overflow (CSO) control in ageing urban areas is a costly and on-going issue. In addition, urban municipalities must deal with other daunting issues such as economics, sustainability, etc. In this paper, we show how decision makers might capitalize on the concept of natural capital or ecosystem services benefits, as well as other economic benefits in sewershed-scale green storm-water infrastructure (GSI) designs aimed at reducing CSO volumes. This concept is demonstrated on a sewershed within the City of Philadelphia using triple bottom line (TBL) estimates of benefits and continuous hydrologic/hydraulic simulations using EPA's Storm Water Management Model (SWMM) coupled with a simple genetic algorithm (SGA). Results are compared to existing conditions. Also explored are situations where property values are excluded from the analysis as a method of promoting economic equity in GSI placement.

Many urban watersheds suffer from degraded water quality caused by stormwater runoff from rooftops, parking lots, streets and other impervious surfaces. Low Impact Development (LID) is a design approach that utilizes stormwater control measures (SCMs) to maintain and restore the natural hydrologic features of a watershed by promoting infiltration of runoff into the soil, treating runoff at its source, and minimizing impervious surface coverage. Peer-reviewed literature is lacking on the application of bioretention, permeable pavement and tree filter boxes to treat urban street runoff on a catchment-scale. A pre- and post-retrofit study has been designed to evaluate the impacts of catchment-scale retrofits on hydrology and water quality. The project will be implemented on two midblock street sections in a residential neighborhood in Wilmington, North Carolina. It includes construction of permeable pavement parking stalls, tree filter boxes and bioretention areas that extend into the street right-of-way, thereby reducing impervious surface area and increasing pedestrian safety. Runoff volumes and pollutant concentrations of bacteria, heavy metals, nutrients, polycyclic aromatic hydrocarbons (PAHs) and suspended solids were monitored from June 2011 to October 2011 at the retrofit site and an additional control site located four blocks to the West. Preliminary results from the pre-retrofit monitoring show mean concentrations of total Kjeldahl nitrogen (TKN) from the control and retrofit watersheds were 2.02 mg/L and 1.52 mg/L, respectively. Total phosphorus (TP) mean concentrations from the control and retrofit watersheds were similar at 0.31 mg/L and 0.29 mg/L, respectively. TKN and TP concentrations observed in this study at both monitoring sites were less than TKN and TP mean concentrations from National Urban Runoff Program (NURP) urban sites and NURP streets. Copper (Cu), lead (Pb) and zinc (Zn) mean concentrations from the control and retrofit watersheds were less than those reported from NURP urban sites and NURP streets. Total nitrogen (TN) and TP yearly loads were greater in the control watershed, which may be due to the greater fraction of impervious surface coverage and fertilizer use in the control watershed. The results and conclusions from this study will help refine street retrofit design standards to meet runoff volume reduction, peak discharge mitigation and water quality goals while increasing pedestrian safety and improving aesthetics in the neighborhood.

Stormwater treatment is entering a new phase with stormwater management systems being required to meet specific numeric objectives, as opposed to the historic approach of meeting guidance-document-provided percent removal rates. Meeting numeric discharge requirements will require designers to better understand and apply the physical, chemical, and biological processes underpinning these treatment technologies. This paper focuses on the potential unit treatment operations available for stormwater treatment and how this theoretical information can be applied to stormwater control practice design.

This paper will describe the process the towns of East Granby, Harwinton and Plainville, Connecticut used to evaluate and adopt Low Impact Development strategies under the Farmington River Enhancement Grants. The CT DEP offered grants to communities located within the Farmington River Watershed to retain qualified consultants to review existing land use regulations in order to encourage the implementation of the LID. The three communities are Plainville, Harwinton and East Granby which all discharge some or all of their stormwater into the Farmington River. This paper will discuss and contrast the approach of the three communities. The Towns of East Granby and Harwinton are similar in size and population. The predominant land use is single family residential with scattered small areas of commercial development along arterial roads. Plainville is currently densely development with very little land available for new residential or commercial development. All three towns are similar to their approach to stormwater management, which focuses on the peak rate control for the 25-year storm event. The paper will describe the land use issues in each community which drove the process to consider LID. It will also show how LID development strategies were presented for consideration and adopted to address these issues. The paper will also discuss how the input and opinions of land use staff can greatly affect the how LID strategies are incorporated into the regulatory framework by insisting on language which reduces the effectiveness of LID in a community.

This paper will describe how LID stormwater strategies were used on two affordable housing projects in Connecticut on sites with multiple environmental constraints. While LID strategies are commonly used to match pre-development infiltration rates and address water quality of post-development runoff, these two projects expand the capability of LID treatment systems to address other stormwater management requirements in a community. The first site contains an upland area surrounded by a large inland wetland area. All development, including stormwater treatment had to occur within the upland area with no direct or indirect adverse impacts on the delineated inland wetlands. The LID systems not only had to address water quality and groundwater recharge issues but also had to provide the capacity to provide volumetric reductions for post-development runoff for the 2-yr to 100-yr storm events. The second site consisted of an area adjacent to a freshwater river that is tidally influenced. The site formerly contained tidal wetlands that were filled with earth material over fifty years ago. The depth of the fill is in excess of 12'. Due to the proximity of the tidal resource, it was required by the municipality to address water quality issues and also provide some detention of post-development runoff to reduce the flooding potential that currently occurs along the river. The LID design on this site not only focused on water quality but also provided sufficient storage capacity to fully contain the 95 percentile storm event. Both sites are being developed by Garden Homes Management, a real estate company located in Stamford, Connecticut. The paper will explain the field testing performed, the design process, including hydrologic modeling to achieve the required stormwater goals. The paper will also describe the construction process for the installation of the LID treatment systems on both sites.

Importance of uncertainty analysis (UA) to estimate the degree of reliability associated with model predictions is being understood. Consequently, literature that describes various Bayesian methods for the assessment of parameter and model predictive uncertainty has been steadily rising. Applications dealing with urban stormwater management are, however, very limited. This study demonstrates successful application of a formal Bayesian methodology for UA of the U.S. EPA Stormwater Management Model (SWMM), a widely used urban stormwater management model, and illustrates the methodology using a highly urbanized watershed in southern California. DREAM_(ZS), a recently developed effective and efficient sampling algorithm, and a generalized, formal likelihood function that addresses the assumptions commonly made regarding error structure including independence, normality and homoscedasticity are used for the UA. Results will include comparison of the simulated error structure with the assumptions made by the likelihood function, histogram of the parameters posteriors, bounds of the 95 percent confidence interval, and the maximum likelihood (ML) predictions. A conventional calibration attempted to compare the ML results derived from the UA with the optimal solutions identified by the single objective calibration will also be presented. Besides illustrating state-of the-art in UA, the study will highlight application of the methodology to developing a watershed management model to mitigate stormwater quantity and quality problems associated with urbanization.

The reduction of the volume of stormwater from storm events is paramount in the mitigation of Combined Sewer Overflows (CSO) required Waste Load Allocations as assigned to the Total Maximum Daily Loads (TMDLs) program mandated in American cities. A recent investigation conducted by the Environmental Protection Agency Office of Research and Development (EPA-ORD), in the urban core communities of Cincinnati and Cleveland, examined the taxonomy and hydrology of urban soils to better understand the distribution of stormwater storage and infiltration capacity across previously unmapped areas. Urban soil mapping historically has not provided the information necessary to implement even the smallest scale stormwater control measures (SCMs). SCM This venture opportunistically sampled vacant lots to perform soil taxonomy on unmapped soils and document the capacity of urban soil to retain the infiltration and absorption characteristics of the parent material. The use of vacant lands for Green Infrastructure and stormwater volume mitigation can simultaneously address reduction in CSO frequency and volume, NPDES Total Maximum Daily Load (WLA-Waste Load Allocations) and social justice issues in struggling post-industrial urban communities.

This study investigates the water quality of the Pasig River in Metro Manila during the construction of river improvements through channel alteration. Statistical and trend analysis of surface water have been performed using the records (2008-2011) of 5 water quality parameters (pH, dissolved oxygen, biochemical oxygen demand, total suspended solids and EC) at 4 observation sites along the Pasig River. The trend analyses were performed using a moving average approach and non-parametric Spearman's rho technique. The results indicate that most of the water quality parameters do not show significant trend; except for BOD and EC where these were found to significantly increasing in some of the observation sites. TSS was significantly decreasing in one site. Apart from these analyses, 14 other water quality parameters, collected annually, were assessed by comparing the values with the Philippine water quality standards. The findings of this study provide useful references for the monitoring of river water quality in Metro Manila.

It is well documented that runoff from roof surfaces carries a wide variety of pollutants including sediment, heavy metals, nutrients and bacteria. Collecting and storing this roof runoff via rainwater harvesting systems could provide water quality benefits due to physical and chemical processes that occur within the storage tank. Four fire stations in Raleigh, North Carolina, USA, were equipped with rainwater harvesting systems. Samples of roof runoff were collected after each storm to determine pre-cistern water quality characteristics. Samples were also collected at the extraction spigot for the system. All samples were analyzed for total suspended solids (TSS), total nitrogen (TN), total Kjeldahl nitrogen (TKN), nitrite (NO₂)+nitrate (NO₃), ammonia (NH₃), and total phosphorus (TP). Water quality data will be analyzed to determine if storing water within a cistern has a significant effect on pollutant concentrations. Water usage data collected during the study period will be compiled and pollutant loads will be computed.

Engineers design a substantial fraction portion of infrastructure that accommodates storm water drainage and conveyance. Estimation models of the response for a watershed typically contain some form of watershed slope as a principal parameter, and the response is usually inversely proportional to that slope. Therefore, as topographic slope decreases, the watershed timing parameter increases. The consequences at low enough slope, is that the timing parameters approach infinite time and the precipitation intensity that is associated with a long averaging time is so small as to be meaningless -- yet low slope environments exist, are populated, and precipitation does generate runoff.

Demographic data suggests that the number of students who will enroll in engineering programs at U.S. universities will decline in the near future. One way to offset the potential reduction in the number of future engineers in this country is to increase the number individuals from currently under-represented groups in STEM majors. For example, women make up more than one-half of all college students in this country but are less than one-fourth of the engineering student body. There are initiatives at all levels to increase the number of women studying engineering, and this paper describes two grass-roots level initiatives at the Missouri University of Science and Technology in Rolla, Missouri. The Missouri S&T geological engineering program and the Women's Leadership Institute teamed to develop two new programs intended to attract rising junior and senior high school women. Girls Go Green and Girls Go Global share many attributes including a focus on hands-on activities, contemplative activities, structured recreational activities, and interaction with undergraduate and graduate students who act as potential role models. Each camp includes theme-specific activities. For example, a multi-part Girls Go Green activity is the erection of a 1 kW wind turbine on a 50 ft guyed tower that requires the girls to learn basic surveying, the use of scratchpad math software (and trigonometry knowledge), and the ability to work together during the wind turbine assembly and erection. In Girls Go Global, female faculty from Brazil and Guatemala led country-specific activities such as a Guatemalan fashion show and a sing-along in Portuguese. Both programs are relatively new, but preliminary data are available that show meaningful direct and indirect yields associated with these efforts.

Water resources development projects inevitably have economic, environmental and social impacts. Impact prediction using computer modeling is a major activity of water resources systems planning and management today and will be no less so in 2050. Computer-based optimization and simulation models incorporated within interactive graphics-audio based decision support systems will continue to help us identify those plans, designs and policies that maximize the desired impacts and minimize the undesired ones as well as making clearer the tradeoffs between the two. By 2050 participants using these decision support systems should be able to embed themselves within and interact with these systems that provide a dynamic virtual reality environment in ways that facilitate and enhance the political process of planning and decision-making as well as provide the desired physical, socio-economic, environmental, ecological information.

A three-dimensional (3D) computational fluid dynamics (CFD) model of an intake with two pumps withdrawing 1.40 m3/s of water from a river is presented in this paper. The model domain includes a 350 m reach of the river to directly include the non-uniform approach velocity distribution in the simulations. A sufficiently high resolution grid consisting of about 1.5 million polyhedral cells are used to resolve the geometric features of suction pipes, pump bells, two pump bays, and the adjoining river. Results of CFD model indicate that the non-uniform approach velocity creates eddies and vortices in the intake. Combined with a 1:4 flow split between the pumps result in complex intake hydraulics that cannot be predicted by a limited area model. An analysis of flow fields shows that swirl angles and deviations of point velocities from their mean satisfy Hydraulic Institute's (1998) guidelines. However, the smaller pump is likely to experience operational problems because of considerably higher turbulence intensity and two surface vortices entering the bell.

A three-dimensional computational fluid dynamics model of an underground pump station with seven pumps operating at a total discharge of 175 MGD is presented in this paper. Each pump withdraws water through a 24-inch-diameter, 360-foot-long suction pipe in a 60-inch-diameter wet well that is connected to a horseshoe shaped conduit at a depth of 425 feet. The model domain includes a segment of a 9-footdiameter intake tunnel, conveying water from a lake, and a 30-foot-diameter surge tank. A high-density computational grid consisting of about 2 million polyhedral cells was developed to resolve the important geometric features of the system. The CFD model predicted steady state velocity, turbulence, and vorticity at several sections, including the pump bell throat. These parameters were analyzed in a manner analogous to that suggested by the Hydraulic Institute. Results indicate that the maximum swirl angle, deviation of point velocity from the mean, and turbulence intensity are considerably smaller than those recommended by HI for a satisfactory performance of the pump station.

A three-dimensional (3-D) computational fluid dynamics (CFD) model of a Kenics static mixer, consisting of 10 helical units, is presented in the paper. The model was used to simulate flow and mixing at high Reynolds numbers (R_E) that are typical (10₃ to 10₆) in water treatment plants (WTPs). A high resolution computational grid, consisting of 1.25 million polyhedral cells, was used to resolve the geometric features of the mixer. An analysis of radial and circumferential velocities shows that the flow field is characterized by regions of reverse flow and the growth and interaction of strong longitudinal vortices. A conservative tracer injected just upstream of the first unit was used to determine coefficient of variation (CV), a ratio of standard deviation of concentration to its mean, of each unit. For flow conditions found in WTPs, the study suggests that four helical units can achieve the desired level of mixing (CV ≤ 0.001).

A three-dimensional computational fluid dynamics model of a 25-million-gallon finished water storage reservoir is presented in this paper. Objective of the study was to optimize hydraulic mixing and water age for a daily flow of 35 mgd. For the existing configuration with a bottom-outlet at one corner, a step-dosing tracer test predicted a mean hydraulic residence time of 0.87. The 10th, 50th, and 90th percentiles (θ₁₀, θ₅₀, and θ₉₀) of the non-dimensional time (θ) were 0.14, 0.65, and 2.0, respectively, and Morrill Index (MI) was 13.92. The fraction of the reservoir volume occupied by dead-flow zone (V_dead) was 0.13. A tracer washout test computed a water age of 96 hours. A relocation of the outlet from the corner to the center improved θ₁₀ to 0.28, decreased MI to 7.16, and reduced the volume of dead flow zone considerably, while lowering the water age by 16 hours. The study demonstrated that a minor design change could significantly improve the hydraulic performance of storage reservoirs.

Cloud computing is quickly becoming an innovative model for delivering IT infrastructure, applications and data management. It shifts the emphasis from static, stand-alone applications to dynamic, shared environments, dynamically allocated among various tasks and accessed via a network. In this paper, we investigate the use of cloud computing for high performance optimization of water distribution systems. The paper covers the general survey of leading commercial cloud computing services, high performance computing (HPC) cloud differentiators and demonstration of the improved HPC cloud implementation. With necessary background information on cloud computing, a prototype of the high performance computing (HPC) cloud is proposed and developed for water system optimization. The prototyped HPC cloud is constructed by using many-core machines that form the cloud platform for running parallel applications. Finally, as an example of cloud-based water distribution optimization, a pump scheduler has been deployed onto the HPC cloud with web-based user interface, through which a user could submit, execute and retrieve optimization analysis jobs.

Copper (II) and zinc (II) were removed from solution using biogenic iron oxides collected from an iron seep dominated by Leptothrix ochracea. Copper sorption kinetics were best described by the standard power function (R₂ = 0.997), while kinetics for zinc followed a pseudo-first order model (R₂ = 0.937). The Langmuir isotherm adequately described sorption for all samples with average R₂ values of 0.933 and 0.952 for copper and zinc, respectively. Maximum sorption, estimated using the Langmuir parameter, ranged from 23.0 to 104 mg Cu/g solids for copper and 0.89 to 20.8 mg Zn/g solids for zinc. Copper and zinc removal on these orders was similar to other natural and engineered sorbents evaluated recently, suggesting further study of biogenic iron oxides as a potentially regenerable substrate should be pursued. Engineered growth of biogenic iron oxides within wetlands may represent a feasible application for storm water or non-point source treatment.

Water is often considered the lifeblood of a community. Water, and especially potable water, is a resource that is limited during many times of the year in sub-Saharan Africa. In locations where water is in short supply community members, especially women and children, spend many hours each day collecting water from wells and boreholes that may be many kilometers from local villages. This presentation highlights the plight of Ddegeya village, Uganda which strives for fresh, clean water on a daily basis. Many of the existing boreholes in the community were not built properly and oftentimes contain little or no water, especially during the dry season. To address this issue, the Massachusetts Institute of Technology - Engineers Without Borders (MIT-EWB) team has explored options for rainwater catchment in the village through several assessment trips and pilot testing of rainwater harvesting systems. The project mission is to find alternative water sources for the Ddegeya community to reduce the need for well water and provide an additional source that is much closer to place of use. Two potential partial above ground tanks designs were evaluated, one constructed with a ferrous cement base and the other with a clay base. In addition, two pump designs were built and tested. Both tank designs were successful. However, the clay-based tank proved to be a viable option that was nearly half of the cost compared to the ferrous cement tank. This presentation will highlight the efforts with the community water board and detail construction designs of the tanks and pumps providing information on the community perspective and design outcomes from efforts to date.

Crude Oil is the major input cost for refiners; however, crude oil's low water solubility places it in a class of contaminants referred to as non-aqueous phase liquids (NAPLs). Crude oil is particularly difficult to recover from saturated porous media, and is often found at residual saturations that act as a long-term ground water contamination source. The pump-and-treat method is one of the most widely used remedial approaches. Then, most experts already knew that low aqueous solubility results in low recovery rate. However, the use of surfactants to increase the apparent aqueous solubility of crude oil was tested for potential use as an enhancement of conventional pump-and-treat. That would increase crude oil recovery rate, reducing the pore volumes and clean-up time. In this paper, blended surfactants, electrolyte, co-solvent and polymer

This paper presents a water management platform by integrating the software on water resources, raw water transmission, treatment plants and distribution networks in the SOA framework. With an example of software development of early warning system for drinking water security, the paper illustrates the distributed system composed by reusable component of data, modeling and application as services. The paper also presents a model of expert system with the knowledgebase reasoning method, optimal computation for selecting the water treatment process in emergency response and process upgrade. A real engineering example in Dongguan, China is given out on water treatment processing adjustment based on seasonal or sudden raw water pollution events. The research is based on the national science and technology significant water special project of China, Pearl River downstream area drinking water safety control technology integration and synthesis demonstration.

Fusing measurements from heterogeneous sensors and sensor networks is critical for achieving accurate measurements of environmental processes at the time and space scales necessary to improve forecasting aid decision making. Due to different measurement accuracies (which may be time-dependent), types of spatial and/or temporal measurement support, and measurement frequencies of the component sensors, it is often unclear how best to combine these data. This study explores the utility of ubiquitous sensors for improving the resolution of areal precipitation estimates through fusion with weather radar observations. The method developed in this study employs Markov random field models to compute the likelihood of rainfall at sub-grid pixels. These likelihoods are used to "unmix" the block-averaged rainfall rate measured by the radar. Simulation studies using known rainfall fields will be used to evaluate the performance of the method.

U.S. EPA Region VII and the Office of Research and Development (ORD) are conducting a large-scale study to identify the prevalence of lead (Pb) and other contaminants in drinking water at four mine waste areas in Washington County, Missouri. Numerous households in Potosi, Richwoods, Old Mines, and Furnace Creek mine waste areas are receiving bottled water as a short-term alternative. The project is designed to provide homeowners with contaminated wells above the action level with Point-of-Use (POU) treatment units as an interim alternative water system until a permanent water system becomes available. The objectives of this project are to collect water samples from a representative set of households, conduct field measurements for the collected water samples, and analyze the collected water samples for total metals, dissolved metals, anions, inorganic parameters, total organic carbon (TOC), and microbiological parameters (E. coli). This paper summarizes all aspects of sampling, analysis, POU selection, economic considerations, and issues resulting from the installation of household POU water treatment devices.

Water distribution networks (WDNs) are the most critical part of a water supply because it is very hard to prevent the effects of any threat on the last points of systems' delivery. To evaluate the performance of WDNs with respect to system failures, it is important to consider both quality and quantity aspects of the water. In this paper a reliability evaluation program (REP) is used to evaluate the reliability of WDNs in dealing with widespread contamination of the system. In this framework, the Monte Carlo method generation is utilized to generate scenarios in a WDN. The characteristics of the generated scenarios include the node of failure as well as the contamination injection place and the time of occurrence. The WDN performance is simulated by EPANET and three measures of the percentage of demand supplied, the time duration which the water quality at the standard level and the time duration which the demand is supplied are calculated. The system reliability is quantified by these measures. To provide a more "real-life" example this framework of evaluation is used in water distribution of Poonak located at Tehran, in Iran. This network contains 78 pipes, 35 junctions. The results quantify the reliability of system.

Water quality may get deteriorated in the distribution network due to natural, man-made, and/or accidental reasons. In order to ensure safe water delivery to the consumers, water quality monitoring in a distribution system is essential. In order to obtain reliable water quality information, monitoring would be required at all nodes of a given distribution system, which is practically may not be infeasible due to economic and time constraints. Thus, it is desired to design a monitoring network for specific levels of service and reliability. The level of service can be defined in terms of the contaminated water consumed or the time lapse between the entry and detection of external contaminants. These service levels are termed as the "volume consumption level of service" and "T hour level of service" respectively. The monitoring network can be identified such that the required level of service can be achieved with minimum number of monitoring locations. In this study, a methodology for identifying the optimal monitoring locations has been suggested using a desired level of service. The developed methodology has been applied to an urban water distribution network to identify the source of accidental contamination. This methodology can be useful to give an alarm signal within a level of service for a potential contamination in a water distribution system.

This paper focuses on the future sate of water resource planning and management. A 2050 vision on water resources is on how to keep up with fields' technological breakthrough in information technology, sensors, networking communication technologies and improving standards of living. Growth of populations, high demands of water, decreasing water resources hydrological variables due to climate change, declining levels of groundwater, pollution, and ever-growing financial predicaments are stumbling blocks to keeping paste with technological, social and economic changes. Increasing energy costs, decreasing yields, debt, unemployment, conflicts and water wars are the possible future stakes. The inter-basin agreements based on actual water value and equitable shares can be the means to avoid the water wars and resolve the conflict of interests by sharing the benefits created by water. Visions of 2050 water resources management are based on more on science and technology and less on arbitrary political decisions Developing decision support systems (DSS) and shared vision on the water benefits, earth observation and remote sensing, data storage and information management and more public awareness and stockholders contributing in Integrated Water Resources Management (IWRM) projects implementations are the development changes for 2050. Furthermore, the advances in engineering education have an important role in society developments, and developing countries are catching up an acceptable pace. Improving the learning science and technology are required to develop practitioners capable of developing and implementing the new ideas against historical barriers. Water resource engineers should be trained to use the strategic approach encompasses "big picture" thinking and planning. This thinking addresses principal issues, structure, organization, and primary objectives utilizing horizontal thinking. In water and environmental management, the parallel thinking or holistic paradigm emphasize on system management in an integrated fashion. Universities around the world will revise their water-related research and education programs to graduate students who are qualified to familiar with the multitude of disciplines such as communication, ecology, economics, engineering, geography, governance, hydrology, law, planning, policy sciences, and more. The university programs will engage students in virtual learning and lifelong learning of interdisciplinary subjects addressing the emerging challenging in water and environmental engineering, planning and management.

Due to strong interactions between the land and atmosphere and the resulting feedbacks as altered by the anthropogenic changes, it is critical to quantify the surface fluxes and boundary layer properties that has direct implications on the regional evolution of hydrometeorology. This study evaluates the impact of irrigation using the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model in the Snake River Basin in Idaho. Our simulation extends for the period in the growing season and compares the control and irrigation runs to assess the irrigation induced cooling on the surface energy balance. Understanding this near surface cooling is directly useful for sustainable water management under changing climate conditions in the future. We present simulated latent and sensible heat fluxes as well as air temperature, relative humidity and the depth of the planetary boundary layer (PBL) over the region.

In this study a regional Water Supply System (WSS), fed from natural sources which depend on uncertain recharge, and from desalination plants with fixed capacity, is to be operated over years. The water is transported through a network to meet consumers' demands. The requirement is to decide dynamically on the optimal operating policy, based on the revealed uncertainty up to the decision point, for minimizing the total operation cost of the system while fulfilling operational constraints at multiple time decision points. The Robust Counterpart (RC) methodology [Ben-Tal et al., 2009] is adopted, which uses a min-max approach assuming that the uncertain parameters reside within a user-defined uncertainty set. The dynamic version of RC is called Adjustable Robust Counterpart (ARC). One of its special tractable versions is the Affine Adjustable Robust Counterpart (AARC) in which the dependence of future decision variables on revealed uncertain data is restricted to be linear. The AARC solution provides a non-probabilistic analysis for multiyear management of WSS under uncertain conditions.

In this research, a forward osmosis (FO) system with its draw solution chamber being a completely-mixed tank (CSTR) reactor was developed for dynamic studies on FO's self-limiting flux behavior. The performance of "fresh water" production and reverse diffusion in the FO process were evaluated under the influence of different mixing intensities and different draw solutes in the draw solution chamber. The experimental data indicated that a) increasing mixing intensity could decrease the dilutive external concentration polarization (ECP), but much stronger stirring is not necessary; b) under the same bulk osmotic pressure of 14 atm, Al₂(SO₄)₃ could make higher flux of the fresh water compared with NaCl solution; c) the sharp flux decrease of the FO system during the first 30 minutes depends on the dilutive ECP, and after about 30 minutes, the flux is relatively stable; and d) reverse diffusion of NaCl solution increases exponentially with an increase in the bulk osmotic pressure, while that of Al₂(SO₄)₃ is negligible due to the bigger diameter of the hydrated aluminum ion. Results of this study indicate that the CSTR FO reactors are suitable for evaluation of dynamic nature of the FO self-limiting flux behavior.

Water scarcity leads to conflict and nowhere is this statement more evident than in those cases where shared watercourses cross or form political. Unless a means of shared utilization of these waters can be created, serious economic, political, financial, and even military consequences may develop, often to the detriment of both, or all, parties involved. Although the impediments to water sharing are many and varied, certain common obstacles exist. An understanding of these obstacles is essential if some sort of mutually agreed upon water sharing is to come to pass. These obstacles are described and discussed. For water sharing to be successful, state and non-state actors must be involved. However, no matter how the non-state actors are involved, the need for a formal agreement to share water between and among the parties involved remains essential. These essential components of a formal water sharing agreement are discussed, to include the need to develop a robust mechanism for resolution of disputes that may arise with respect to the terms of the agreement.

The potential for sediment re-suspension and washout present in conventional stormwater pollutant removal systems is a continual threat to water quality. Pollutants and sediment stored within the sumps of these devices from previous storms are subject to washout in larger wet weather events if not properly isolated from scouring velocities. To demonstrate the possibilities of separators contending with washout concerns lab testing was performed and simulated with CFD on two hydrodynamic separator configurations - one with an internal bypass and one with an isolated sump region. Testing designed to assess washout conditions for the hydrodynamic separators was performed at 50% sediment storage capacity. A flow rate 200% of the treatment flow rate was tested for washout or scour. The same hydrodynamic separators were modeled with computational fluid dynamics (CFD) analysis at concurrent flow rates to the lab testing in order to visualize the flow regimes within the device. Velocity plots indicate areas of high velocity with the potential for scour. This paper reviews the results of the washout tests and compare and contrast the two systems using CFD to provide better understanding of the flow regimes within the devices.

Recent advances in remote sensing (RS) approaches have provided the capacity to acquire water quality information at spatial and temporal resolutions beyond the capability of infrequent and point scale in-situ measurement. Through integrating remote sensing data with Geographic Information Systems (GIS), an advanced approach to study water quality issues is possible. Traditional water quality assessment and monitoring techniques are time, data and consequently capital intensive - often beyond the means of developing countries. Utilizing the geospatial capacity of RS and GIS approaches provides a cost-effective and research quality solution to these issues. The purpose of this paper is to present an integrated approach utilizing geospatial techniques to address water quality issues under the framework of US Environmental Protection Agency's (USEPA) Total Maximum Daily Load (TMDL) program. A TMDL is the calculated maximum amount of a pollutant that a waterbody can receive without violating the water quality standard appropriate for its intended use. This paper will demonstrate the usefulness of these technologies by proposing a RS and GIS based water quality predictive model. The future goal of this study is to apply the proposed strategy for developing countries where project budgets are usually very limited to show the usefulness of geospatial technologies in optimizing limited resources of a project without compromising the reliability of outputs - rather more realistic outcomes are expected to be achieved.

There are numerous options for incorporating proven and emerging waste conversion technologies into a sustainable integrated solid waste management system. The higher costs of advanced technologies may be offset with revenues from the sale of renewable energy (electricity, liquid fuels and solid fuel); renewable energy credits (RECs), carbon offsets and recovered recyclable materials. For some technologies there is also the possibility of the recovery of existing landfill airspace and property. State and federal incentives in the forms of grants, loan guarantees and tax credits have also been available to improve the economic benefits of emerging waste conversion projects. Numerous synergies may be realized by integrating proven and emerging processes for production of renewable energy from municipal wastes. New and emerging technologies are currently under development for conversion of municipal wastes into liquid biofuels (biodiesel, synthetic diesel, synthetic gasoline and cellulosic ethanol). Driven by a growing awareness of climate change, greenhouse gasses and energy efficiency, renewable energy projects derived from municipal wastes are now seen in a new light. A synergistic approach to managing municipal processes on a single campus is compatible with the goals of sustainability, waste reduction, and development of renewable energy for local use. Renewable energy in the form of steam, heat, and electricity can also be used to internally power municipal water treatment processes. The internal use of the electricity may result in significant savings to the municipality as the purchase of electricity from the local electrical utility is reduced, or avoided. In this case, the savings may be shared between the solid waste and other public works departments.

Biosolids management can be a source of greenhouse gas emissions (GHG). Biosolids treatment and end use technologies can constitute up to 40 % of total emissions associated with wastewater treatment. Combustion and landfilling of biosolids are the main sources of emissions. The greenhouse gases that have the potential to be emitted from composting operations are CH₄ and N₂O. Composting is an aerobic operation, but since the environment is not uniform in a compost pile, anaerobic pockets may exist. If the C:N ratio is < 30 and the moisture content is < 55 % GHG emissions will not occur during the composting process itself. Land application of biosolids will add organic matter to the soil which will help sequester C. Biosolids also reduces the need for commercial fertilizers which also produces additional credits for GHG emissions. There is great uncertainity in N₂O emissions from land application.

Concerns over global climate change have spurred interest in accounting for carbon emissions from human activities. Most of this effort has focused on emissions from vehicles and energy use within buildings. However, relatively little is known about how the urban landscape, and particularly stormwater management, contributes to the carbon footprint of urban areas. The objective of this work was to present a method by which carbon emissions attributable to the construction and maintenance of stormwater control measures (SCMs) and conveyances could be predicted. This method was then applied to present a comparison of the carbon footprint of eight common SCMs and three conveyance practices. The carbon embodied in construction materials represented a prominent part of the carbon footprint for green roofs, permeable pavement, sand filters, rainwater harvesting systems, and reinforced concrete pipes while material transport and construction dominated that of bioretention systems, ponds, wetlands, level spreader-grassed filter strips and concrete-lined swales. Despite accounting for sequestration by vegetation in these systems, only stormwater wetlands and grassed swales were predicted to store more carbon than was released through construction and maintenance.

Uranium is a naturally occurring radioactive element that exists as a trace element in natural materials such as soil, rocks and minerals. Average crustal abundance is 2.7 ppm U. Due to the chemical characteristics of uranium it can be absorbed by the vegetables and also dissolved in water.

Tenkiller Lake is a Corps of Engineers reservoir operated by the Tulsa District located in Oklahoma. Because of concern over possible impacts to the reservoir of poultry waste applied to agricultural lands in the basin, a hydrodynamic and water quality model of Tenkiller Lake was constructed to evaluate how the reservoir would respond to changes in nutrient loading from the watershed. The CE-QUAL-W2 model was calibrated to field data over the period of January 1, 2005 through September 2007. Comparisons of field data to model predictions were made for water level, temperature, NH₄-N, NO₃-N, PO₄-P, total N, Total P, chlorophyll a, and dissolved oxygen at multiple reservoir sites at various depths. The model was used to predict the response of the reservoir to changes in Total P loading in the watershed over a 50-year period. Several scenarios were run with the model including no changes in nutrient loading from the watershed, natural conditions, and cessation of further land application of poultry waste in the watershed. Results and recommendations for achieving water quality targets in Lake Tenkiller were outlined. The cessation scenario showed that even after 50 years, the reservoir would still not have recovered to a natural pristine state. High residual Total P loading in the basin from past agricultural practices would continue to degrade water quality.

Ceramic pot filters (CPFs) are effective, low-cost household water treatment devices. CPF lifetime is assumed by the manufacturer to be one year; however, there are no definitive studies which quantify CPF lifetime. The objective of this preliminary research was to quantify the lifetime of a CPF in terms of the amount of water that can be filtered before the flow rate becomes unusable. Constant head flow rate testing, porosity testing and water quality testing were performed in a laboratory using three CPFs to establish baselines for comparison with field tests using six CPFs manufactured in Antigua, Guatemala. Interviews with 17 CPF users were performed in Guatemala to obtain information on their water and CPF usage. The limited laboratory and field testing showed that flow rate values decreased with increasing cumulative volumes of treated water. The field test data was compared to the laboratory data to estimate the volume of water that would be filtered before the flow rate decreased to an unusable rate. This volume was found to be approximately 1,500 L, which corresponds to a six-month time for a family of six using World Health Organization estimates of daily water consumption. The water quality data collected in the field showed that turbidity decreased after filtering through the CPFs while conductivity and hardness both increased slightly. This increase in conductivity and hardness may be due to rainwater being used as the water source, which typically has low mineral content with very little dissolved solids and hardness to begin with. The number of families interviewed is too small of a data set to provide conclusive results. But the anecdotal data collected from the interview process suggests that the subject families did not believe that a single filter could provide enough drinking water for a family for one year. The large number of CPFs in use throughout the world means that the technology has the potential to have a significant impact on large number of people, and it is recommended that a formal study involving large numbers of filters be conducted to quantitatively estimate CPF lifetimes.

Water quality and hydrodynamic models of proposed hydroelectric projects in Guyana and in Peru were developed to help evaluate the environmental impacts on water quality and greenhouse emissions of these new reservoirs. The public domain 2-dimensional (longitudinal-vertical) hydrodynamic and water quality model, CE-QUAL-W2, was chosen for these projects. Modeled state variables included water surface elevation, velocities, temperature, dissolved oxygen, labile/refractory dissolved organic matter, labile/refractory particulate organic matter, CBOD, algae, PO₄-P, NH₃-N, NO₃-N+NO₂-N, suspended solids, pH, alkalinity, Total inorganic C, dissolved CO2, and sediments. CO₂ fluxes from the reservoirs were also estimated. New state variables, methane (CH₄) and hydrogen sulfide (H₂S) constituents were added to the model including the processes of anaerobic release from the sediments and reaeration. Water quality model simulations were conducted for low, average, and high flow years and included the river systems downstream of the proposed reservoirs. The impacts of reservoir upon dissolved oxygen, carbon dioxide, methane, hydrogen sulfide, temperature, algae, and carbon loads were evaluated. Atmospheric emissions of carbon dioxide were predicted for the reservoir and river downstream.

It has been suggested that ceramic pot filter systems which are used for water disinfection in developing countries, can be subjected to recontamination due to improper use and maintenance. Two phases of experiments to evaluate recontamination potential were conducted in the laboratory and in the field and a third phase was conducted only in the field in Guatemala. Phase One identified the potential for recontamination which tested three different mechanisms: placement of the filter unit on a contaminated surface, unsanitary handling of the spigot, and faulty cleaning of the entire system. The results suggest that only concentrations of fecal coliforms which exceeded typical Guatemalan source water concentrations by several magnitudes resulted in recontamination. Experiments were repeated in Guatemala during a total of four weeks. Phase Two consisted of field studies during the four weeks in Guatemala in which five communities were visited to gather CPF users' testimonials and to collect CPF-treated water quality data. Of the 44 CPFs tested in the villages, 33 percent showed signs of recontamination. These results indicate that recontamination is possible but more likely develops from human error than equipment malfunction. Phase Three investigated the potential of two filter reactivation techniques to remove bacteria from the unit in the event that recontamination does occur. The first method was to quantify fecal coliform die-off of two separate Guatemalan rivers. This produced evidence that fecal coliforms die-off over time periods exceeding 12 days. The second method of pot reactivation was to flush eight liters of disinfected water through the CPFs. This found that the bucket and spigot components were free of bacteria but that fecal coliforms were still present in the treated water. These results indicate that disinfection of a contaminated CPF system requires an intervention beyond simple flushing to restore a contaminated CPF system.

Microorganisms in streams are potentially transported as freely suspended organisms or attached to particulates. Many water quality models currently neglect resuspension, an important process to predict in-stream bacteria concentrations. The objective of this work is to measure resuspension of E. coli from different substrates under a range of flows. An assessment of the attached fraction and resuspension rate was completed by measuring E. coli concentrations in a recirculating flume at two locations. The test was completed for three different substrates: sand, sand-silt, and sand-silt covered with biofilm. The experiments were conducted at flows below, and above the calculated critical shear stress, as well as two different water depths. Attachment ratios were assessed using a combination of shaking and filtering techniques. The results showed that attachment ratios increased as particle sizes decreases and cohesion increased. Attachment decreased after the critical shear stress was surpassed; sand attachment decreased from 14.29% to 11.44%, sand-silt decreased from 42.01% to 20.59% and biofilm decreased from 82.52% to 11.77% (values averaged for two collection points). The resuspension calculations show resuspension of attached particles at the first test point (8.54E-7 to 1.74E-5 CFU/m₂/s) and deposition at the second test point (-2.99E-5 to 1.69E-5 CFU/m₂/s). At the first sample location there was a steady increase of resuspension as shear stress increased whereas at the second sample location the resuspension rate remained nearly constant.

This study investigates the technical and economic feasibility of adding satellite water storage tanks to the current intermittent water distribution system of Kathmandu, Nepal to provide a more reliable continuous supply of high quality drinking water. The main objective of the research includes [1] modeling the existing intermittent water distribution network and the proposed continuous water distribution network; [2] evaluating water quality under both systems; and [3] investigating the economic feasibility of using satellite tanks. This paper focuses on the first objective of modeling the existing and the proposed water distribution network. The computer model SWMM has been used to simulate the hydraulic behavior of the study site under both intermittent and continuous flow conditions.

In December 2010, EPA released the TMDL for the Chesapeake Bay. Specifically, the TMDL sets Bay watershed limits of 84.4 million kg/yr of nitrogen, and 5.7 million kg/yr of phosphorus, a 25 % reduction in nitrogen and 24 % reduction in phosphorus.. Agriculture is the largest single source of nitrogen, phosphorus, and sediment loading to the Bay. Agricultural activities are responsible for approximately 44 percent of nitrogen and phosphorus loads delivered to the Bay and about 65 percent of sediment loads delivered to the Bay. Animal operations account for more than 60 percent of the region's annual farm product sales. In the watershed, the six major types of animal operations are dairy cows, beef cattle, pigs, egg production, broilers, and turkeys. The three major animal production regions in the watershed, according to livestock concentration, are the lower Susquehanna River in Pennsylvania, the Shenandoah Valley in Virginia and West Virginia, and the Delmarva Peninsula in Delaware, Maryland, and Virginia. Installation of new BMPs will be required to meet the TMDL requirements for agriculture.

The inherent complexities of multi-reservoir flood control systems and their operation conditions along with the improvements of optimization methods have led to a positive trend on better development of these models. This trend tends to provide the operators of these systems with more practical solutions. Although optimization models can provide appropriate solutions for operation of multi-reservoir systems, the exact implementation of these solutions in real world is not guaranteed. This arises mainly due to high level risk of flood situation, real time operation constraints, high level uncertainties of inflows that usually are overlooked in optimization models, and so on. These problems in implementing the operation policies lead the water resources managers to more flexible tools such as simulation models as complement of optimization models for developing more practical solutions. A simulation model based on system dynamics approach is proposed in this study because of its high potential for helping out improving these conditions. The Karkheh multi-reservoir flood control system which consists of six large multi-purpose reservoirs is selected as the case study, and its operation polices that recently developed by a new multi-purpose MILP optimization are examined in this study. The initial results of the study show high performance of the proposed model which is able to enhance the initial solutions of optimization model. Also, some sensitivity analysis on the uncertainties of river basins inflows are done that is a unique capability of simulation models in analysis of uncertainties.

In North Texas, the Tarrant Regional Water District (TRWD) and the City of Dallas both require major new pipelines to bring water from East Texas. Agreements have been reached to share new conveyance infrastructure, which will be jointly funded and used to save hundreds of millions of dollars in capital costs when compared to building independent pipelines. A shared pipeline will also link the two agencies' water supply reservoir systems, creating the potential to share water supply. Preliminary assessments of water sharing suggested there may be beneficial opportunities to either improve supply reliability or reduce operating costs under certain conditions. The analysis focused on a variety of ways that each supplier could share supply with the other. Rules and operational strategies were tested with an integrated operations model. The most promising concepts were refined, rules were developed to initiate and terminate water sharing, and these results were used to suggest an operational strategy for this type of water sharing.

Three objectives were considered for examining the operation of Sardar Sarovar Project (SSP) reservoir using this Multi objective stochastic dynamics programming (MOSDP) algorithm. These objectives were (1) To maximize annual release target. (2) To maximize hydropower production after satisfying the canal demands as high as possible. (3) To maximize the reliability of hydropower production.The developed model was used to find out an optimal release policy for the Sardar Sarovar Project (SSP) reservoir, a multipurpose and one of the most controversial reservoirs from ecological point of view on the Narmada river in Central India. The reservoir is the tail end reservoir in the river system located in the state of Gujarat (India), 95 km upstream from Gulf of Cambay and has a gross capacity of 9500 Mcm with live capacity of 5800 Mcm. It has irrigation and hydropower as main objectives besides M&I water supply and flood control as other objectives.The MOSDP reservoir operation policy for SSP reservoir would result the maximum possible canal release from MOSDP Model for SSP reservoir at 75% reliability would be 9749.55 Mcm which would be 1931.94 Mcm (11681.49-9749.55) less than the actual project demand. It would be possible by using MOSDP Model to generate 49 MW of firm power, whereas the firm power generation at 3rd phase of development of SSP was proposed as zero in the project report. The reliability or risk is one of the most important objectives in the water resources management problems. MOSDP helps the decision maker by providing not only the trade-off ratios, but also the achieved reliability levels of each objective. Thus it helps the decision maker to take a rational decision on the best compromise solution. For the given project demand of 11681.49 Mcm, MOSDP reservoir operation Model produced better results in terms of annual canal releases and annual energy generation for 75%, 80% and 90% reliability levels, compared with SDP reservoir operation Policy. Finally, the use of the proposed strategy of exhaustive analysis through these models suggests a promising scheme for reservoir operation of a single multipurpose reservoir, which is likely to guarantee an optimal operation policy.

This paper presents the use of evolutionary computation for simulating reservoir release rates that are central to developing hydrologic reservoir routing models for Lake Shelbyville and Carlyle Lake. The two lakes, which are located in the Kaskaskia River watershed in Illinois, are multipurpose reservoirs operated by the U.S. Army Corps of Engineers to meet flood control, water supply, navigation, recreation, and conservation needs. To date, the reservoir storages apportioned for water supply and navigation needs have not been fully utilized. The objective of the current study is to develop a model for examining the potential impacts of increased water supply and navigation uses on lake levels during severe drought conditions. The reservoirs have their own operating schedules that include ranges of seasonal release rates based on reservoir pool elevations. In this study, storage routing and multi-objective evolutionary algorithms were coupled to simulate reservoir release rates on weekly basis using long-term historical records of daily inflows, storages, reservoir pool elevations and outflows. The simulated weekly release rates for the two lakes complement their respective reservoir routing models and the modified reservoir routing models will ultimately be coupled with previously developed Kaskaskia River watershed model. The resulting coupled model will be able to provide simulations of storages and reservoir pool elevations for the two lakes under varying climate and water use conditions, in addition to simulating flows at different location in the Kaskaskia River watershed. The multiobjective evolutionary algorithm used in this study was effective in simulating the reservoir release rates and its application was instrumental in developing the modified reservoir routing models for Lake Shelbyville and Carlyle Lake.

Two catastrophic floods in the Chehalis River Basin in west central Washington in the past decade prompted several initiatives to manage flood risk in the basin. One initiative was the development of a comprehensive flood warning system to improve emergency response to developing flood threats and to improve the operating environment for future dams and or levees in the basin. After a needs analysis canvassing stakeholders with interests in the basin, a flood warning system was implemented that included an expanded rain, temperature, and stream gage network, an internet based data collection, management and distribution system, as well as inundation mapping for approximately 100 miles of stream channel. The system leveraged existing automated gage networks in the region, an internet based data management service, and National Weather Service river forecasts to form the core of the system. The web site features total public access to observed hydrometeorological data, weather forecasts, quantitative precipitation and temperature forecasts, local road conditions as well as links to other critical flood preparedness resources. A sophisticated alarm manager is included that enables automatic message transmission via email or text messaging to mobile devices when user specified alarm criteria are met. Neighborhood level inundation mapping keyed to the full range of National Weather Service river forecasts covering initial monitoring stages through minor, moderate and major flooding is included. Residents can clearly see where and when flooding will occur relative to homes, critical facilities, and avenues of ingress and egress in advance of anticipated flooding. The Chehalis River Basin flood warning system will be described and summarized. In addition, it will be shown how the system is easily scalable to statewide application.

By 1939 plans for capital ships began exceeding the capacity of the canal's 110 foot wide locks, and Congress approved funding of a Third Locks Project, which began that year. It was prematurely shut down in March 1942 because of America's entry into the Second World War. In 1946 Congress approved a new round of studies examining the feasibility of excavating a sea-level canal because of the threat posed to the existing locks by nuclear weapons. These plans were approved, but never funded by Congress because the Korean War broke out in mid-1950. A third generation of sea-level canal studies were undertaken throughout the 1960s, as part of the Atomic Energy Commission's Project Plowshare. Plowshare proposed to employ strings of thermonuclear warheads set at various depths to excavate a new canal across the Panamanian Isthmus. These studies fell victim to increasing concerns about environmental impacts, and were quietly cast aside in the early 1970s, during the Vietnam Conflict. A few years later (1977) the Carter Administration signed a treaty with Panama that provided for a 20-year transition of the canal's ownership and operations, between 1979-99. In 1999 the Panama Canal Authority (ACP) assumed charge of all aspects of the waterway. In 2006 Panamanian voters approved a $5.2 billion expansion of the Panama Canal known as the Third Set of Locks Project, proposed by the ACP. This measure was funded by the National Assembly in July 2007. The additions will double the capacity of the Panama Canal by 2014 by allowing more and larger ships to transit the Canal. The canal presently generates about half of Panama's revenue.

This paper provides an overview of the key design aspects of the $3.5 billion Panama Canal Third Set of Locks design-build project. The design of the project is being prepared by MWH as lead of the CICP Consultores Internacionales JV Design Team for Grupo Unidos Por el Canal (GUPC) the construction JV. The paper presents a summary of the concept design prepared by the Owner, the Panama Canal Authority (ACP), bid technical specifications, and the consequent tender design development that led to the highest-ranked technical proposal and lowest design-build price. Also described in detail are several of the critical design elements of the project, specifically: the lock filling and emptying studies, design of the lock concrete structures (lock chambers and lock heads), and design of the unique "rolling door" type lock gates. The paper concludes with a summary of design advances that are being incorporated into the Third Set of Locks.

For more than 500 years, French visionaries dreamed of a shortened water route from the Mediterranean coast in southern France to the Atlantic coast in western France—a route that would enable French goods to be transported without being subjected to threats from Barbary pirates and without passing through the Spanish-controlled Strait of Gibraltar. The most feasible route appeared to be a 240 km (149-mile) canal connecting the Aude River, which flowed to the Mediterranean Sea, and the Garonne River, which flowed to the Atlantic Ocean. In addition to the sheer work of excavating a canal over that distance and creating bridges and aqueducts to carry the canal over dozens of streams in its path, two major technical problems had to be solved: first, the creation of a system of locks that would lift the canal more than 183 m (600 feet) over the watershed divide between the two rivers; and secondly, developing a water supply to feed the canal where it crossed the divide. In 1662 Pierre-Paul Riquet, a wealthy farmer and tax collector from southern France, began a campaign which ultimately convinced King Louis XIV of the feasibility of the project. Work on the canal began in 1666. Upon its completion in 1681 the Canal du Midi was considered the greatest engineering accomplishment of its time. In 1996 it was designated a World Heritage Site by UNESCO.

Joseph Pennell, one of the greatest lithographers and print-makers in the United States in the first quarter of the 20th century, saw in the work of the engineers of his time the pursuit of both utility and beauty. He also understood that the process of creating structures results in a series of fleeting scenes, each with a beauty and vitality that is best captured on the construction site. He called his efforts to capture these scenes "The Wonder of Work," and those efforts took him to the sites of some of the most spectacular projects in what some call "The Golden Age of American Engineering." Pennell traveled to Panama in 1912 to create images of the Panama Canal under construction—the greatest engineering work of his time. The 28 lithographs he produced there are some of the greatest images ever created of a project under construction. This presentation consists of a selection of some of the most dramatic of these images, accompanied by his reflections on what he saw and felt as he labored to capture the ingenuity of the plans for the canal and the Herculean efforts expended to transform the plans into reality.

The Panama Canal opened just as the First World War erupted in August 1914. The newly completed canal was underutilized and plagued with closures by massive landslides throughout its first quarter century of operation. In 1916 President Woodrow Wilson empowered the National Academy of Sciences to undertake a scientific study of the landslides and report on how they might be mitigated. During the interwar years the canal became a naval bastion almost without peer in the western world, but plans for capital ships began exceeding the width of the canal's locks by the late 1930s.

The Texas Section of the American Society of Civil Engineers has an active Historic Civil Engineering Landmark recognition program. This paper describes that program and specifically focuses on several water-related landmarks recognized by the Section and national ASCE. Ten national Historic Civil Engineering Landmarks in Texas have been recognized by ASCE, while 17 additional landmarks have been recognized by the Section. The landmarks are comprised of bridges, roads, dams, seawalls, structures and even markers which are essential elements of civil engineering history in Texas. This paper presents three national ASCE and two Section landmarks with particular significance to the water resources industry: the Houston Ship Channel, Denison Dam, the San Antonio River Walk and Flood Control System, Medina Dam, and the Franklin Canal.

The Treaty of Guadalupe Hidalgo ending the Mexican American War in 1848 included an provision guaranteeing American right-of-passage and transit across the Mexican Isthmus of Tehuantepec, viewed as the shortest practicable route across Central America, 2,400 nautical miles shorter than the route across the Panama. The California Gold Rush of 1848 brought thousands of gold seekers and soldiers across the Panamanian Isthmus, including future President Ulysses S. Grant. In the early 1850s Americans also established a regular transit path across Lake Nicaragua, which flourished until completion of the First Transcontinental Railroad in May 1869. In 1879 American engineer James B. Eads presented a scheme for a quadruple track ship-railway across the Isthmus of Tehuantepec in Mexico, while other American interests favored the old route through Nicaragua. Led by Suez Canal builder Ferdinand de Lesseps, the French set their sights on Panama in 1881 and began excavating a sea level canal in 1883, similar to that at Suez. While excavating the highlands along the Continental Divide in 1884, damaging landslides began slowing progress at Culebra and Cucaracha. Health epidemics related to outbreaks of yellow fever and malaria killed approximately 5,600 people, including 460 French engineers. The ever-increasing volume of landslides and the death toll bankrupted the enterprise and the French abandoned the project in 1889. Subsequent attempts to re-start construction met with failure in 1894, because the project was under-funded. The French then focused their efforts on selling their franchise and equipment to the United States. This sale eventually succeeded, in thanks to considerable political intrigue, Nicaraguan postage stamps portraying the Momotombo volcano, and American intervention in helping to establish Panama as a sovereign entity, separate from Columbia. Panama from they succeeded in selling their franchise to the United States in 1903, shortly Americans helped Panama separate from Columbia.

When the United States took over title of the French canal franchise in Panama in 1903 they approached the project with vigor and confidence, treating it as an enormous railroad engineering project. By 1907 the various excavation problems led American engineer John Stevens to redesign the project, using a series of three locks at either end to lift ships 85 feet and transit across man-made Gatun Lake. In 1908 control of the project passed to the Army Corps of Engineers, who completed the project in August 1914, excavating 225 million cubic yards of material at a cost about 260% beyond that originally envisioned, which required an additional 2-1/2 years to complete. Despite all the setbacks and cost-overruns, the project was the jewel of an emerging American empire, and its contributions to world health and sea-born commerce were without precedent.

New Mexico suffered through a long Territorial period from 1846 to 1912 during which our most significant water resource administrative act was passed in 1907, thanks to a U.S. Geological Survey (USGS) lawyer. The good news is that we are still following the same basic water code; the bad news was the time lost prior to its enactment and the lack of needed resources-data on which to base management policies and rules. Stream gauging was not started until 1888 and then thanks only to the USGS. New Mexico became a territory with the end of the Mexican-American War and the 1848 Treaty of Guadalupe Hidalgo. There were hundreds of acequias, locally managed irrigation systems in existence at that time, mostly in the northern part of the state. Many more were to come with the end of the Civil War and diminished threats of Indian raids, perhaps as many as 1,000 acequias. These ditch associations derived their operating rules from their ancestors in Spain: first to use water from a particular stream gave them the first in right to use during periods of drought; a stream diversion point was specified; use of water was tied to a particular parcel; use was restricted to beneficial purposes; and only enough water was permitted to grow a crop. The Territorial legislature got off to a bad start by enacting laws that were counter to these policies. Examples of many of these blunders are offered. The population grew and by the1880's the need for larger irrigation systems began to emerge. Again, the Territorial legislature missed the mark by passing laws that lead to conflicts between down stream, prior water users, and the new developments. A serious drought on the Rio Grande in the late 1880's and early 90's was exacerbated by excessive upstream water use. The water shortages lead to a serious international conflict when the river went dry at El Paso and Juarez. An interesting associated story involved Major John Wesley Powell's non-politic solution to the problem. The situation was not resolved until the signing of the 1906 Treaty with Mexico and the building of Elephant Butte Dam by the Bureau of Reclamation. The Territorial water code of 1907 mirrored Hispanic water-use customs for all new appropriations, but it also opened the flood gates to new requests. In 1907, the Territorial Engineer received applications for two million acre of new irrigated-lands and he approved over 700,000 acres of new irrigation in 1907-08 without adequate records of existing uses by the acequias and without sufficient flow records. The 1907 law did not speak to ground water use. The Territorial Legislature left New Mexico in a bad spot as we approached statehood in 1912.

In general, there are three major factors that determine the accuracy of 2-D hydrodynamic modeling results as far as their use for floodplain delineation is concerned. Those are: (a) hydrology-related factors that are the drivers of the hydrodynamic models (empirical models such as Rational Method, and process-based or physical models that account for both temporal and spatial variability such as HSPF, HEC-HMS); (b) accurate representation of site conditions (surface topography, channel morphometry (geometry), control structures and infrastructures); and (c) boundary conditions (fluxes in and out of the model domain). All of these factors affect accuracy of modeling results and consequently the extent of floodplain maps, especially in areas with significant urban topographic features and variation in land use, and areas that lack adequate storm water conveyance. The traditional approach of 1-D Steady State modeling is by nature more conservative, simpler to conduct, requires lower level hydrology data (generally Q₁₀₀ and Q₅₀₀ peak flows) and it is readily accepted by the regulatory bodies (e.g. FEMA and the States), although it is often less accurate. On the other hand, the Unsteady State 1-D and 2-D modeling approach requires a higher level of hydrologic data (time series of discharges or hydrographs at many locations), higher levels of output analysis and more rigorous model calibration, and often more effort in convincing the regulatory bodies that the results are more realistic. Calibration can be very challenging when 2-D models are applied; depending on the accuracy of topographic information, complexity of the physical domain, model grid size, as well as number/location of inflows in the model set up. Significantly, the small simulation time step and interpolation of time series boundary inputs, the execution time can be very long even with highspeed computers. In this paper, we will describe the results of 2-D fine grid hydrodynamic modeling efforts using the FEMA-approved FLO-2D software to more accurately delineate floodplain extent in comparison with conventional 1-D HEC-RAS models in Ventura County, California. Although the level of data requirements for the 2-D model is more extensive and the computational time is substantially longer than that of the 1-D model, the results are much more accurate and corroborate with the weight of evidence in recent flooding events. This approach is also gaining more acceptability by the local entities submitting LOMC/LOMR/CLOMR and the regulatory body requirements because of animation capability, graphical user interface, and use of GIS layers to depict flooding extent to which they can easily relate.

Gravity currents (GC) caused by saline water propagating into freshwater bodies is an interesting phenomenon in environmental fluid mechanics that has received attention from several past investigations. Numerical modeling tools have been proposed in such investigations to predict the advance, mixing and spreading of these currents. While modeling studies focusing on the mixing of the current with ambient water often involve the application of the Navier-Stokes equations, the shallow-water equations (SWE) that are much less computationally intensive can also be used. SWE model targets advance of the front (e.g. velocity) and the general distribution of the dense fluid mass. An ongoing experimental investigation performed at Auburn University has compared observed gravity currents (GC) with predicted GC applying different modeling approaches, including the three-dimensional Environmental Fluid Dynamics Code (EFDC) and SWE model alternatives. The latter models, developed in the context of this study, have been developed using different strategies including nonlinear schemes based on Riemann solvers using Finite Volume Method. A comparison is performed between the EFDC and the SWE model predictions and corresponding experimental measurements. An assessment of the applicability of different modeling approaches is presented.

We present a robust and numerically efficient model for unsteady flow routing through dendritic, looped and networks comprised of dendritic and looped sub-networks. The model builds upon the application of Hydraulic Performance Graph (HPG) to unsteady flow routing introduced by González-Castro and Yen (2000) and adopts the Volume Performance Graph (VPG) introduced by Hoy and Schmidt (2006). The HPG of a channel reach graphically summarizes the dynamic relation between the flow through and the stages at the ends of the reach under gradually varied flow (GVF) conditions, while the VPG summarizes the corresponding storage. Both, the HPG and VPG are unique to a channel reach with a given geometry and roughness, and can be computed decoupled from unsteady boundary conditions by solving the GVF equation for all feasible conditions in the reach. Using HPG's and VPG's results in a robust and numerically efficient model for flow routing because the performance graphs (PG's) provide pre-computed overall GVF solutions of the momentum and mass conservation equations and the computations for routing through the system mostly involve interpolation steps. Although, the HPG/VPG approach is a highly numerically efficient and robust approach, previous routing models based on this approach were formulated for single prismatic channels or channels in series, so they are not suitable for routing through dendritic and looped networks. Our model overcomes the limitations of previous HPG/VPG formulations, as it can be used for unsteady flow routing through any river network. In our model (OSU Unsteady Routing) we solve a system of nonlinear equations assembled based on information summarized in the systems' HPG's and VPG's, continuity and compatibility conditions of water stages at the union of reaches (nodes), and the system boundary conditions. We exemplify the applicability of OSU Unsteady Routing to a looped network and contrast its simulation results with those from the well-known unsteady HEC-RAS model.

An integrated storm surge and inundation modeling system is implemented in an existing software package DSS-WISE developed at the National Center for Computational Hydroscience and Engineering. The model is packaged in a GIS based graphical user interface. In the present study, the existing model is enhanced with storm surge prediction capability by including a hurricane track model and some additional forcing terms. The governing equations are discretized by a conservative finite volume method and the HLLC Riemann solver. The topography is defined by Digital Elevation Model and surface roughness can be prescribed based on land use pattern. The wind shear stress is calculated using a parametric wind model. The hurricane pressure field is computed using a hurricane track model by supplying the track of the storm, central pressure, radius of maximum wind and its forward speed. The discretized equations are solved explicitly. The enhanced DSS-WISE model is verified by solving analytical tests commonly used for verification study of shallow-water models. The simulation of Hurricane Gustav that made landfall on the Louisiana coast in 2008 is also demonstrated and the preliminary results are analyzed.

Siphons are commonly used on the discharge side of large pumping systems to reduce the design operating head by up to 30 feet through siphonic recovery. These systems are typically used in power plant cooling water systems to increase the efficiency of the plant and in large flood control stations to reduce the motor and power requirements. In controlled settings, such as a power plant or process system, the siphons are often started with the aid of a vacuum system. In critical flood control applications, it is often desirable to have the system "self-prime" to reduce the dependency on mechanical systems during critical flood control events. Also, in remote applications, the high point may be a considerable distance from the station or available power supply, so eliminating the need to provide vacuum assist can significantly reduce project costs. The physics and limitations of siphons are well understood, but there is a limited amount of design guidance regarding self-priming systems. The guidance that does exist covers general design and operation in terms of siphon downleg velocity and slope requirements necessary to establish a primed condition. However, very little information exists regarding the impacts of downleg alignment or length on actual priming characteristics, such as initial head reduction and total priming time. This paper presents the development and results of a physical model study that was intended to simply confirm the self-priming characteristics of a typical siphon. Instead, the study identified an unexpected interaction between the pipeline alignment and the flow characteristics, which significantly extended the time required to selfprime. A change in the horizontal alignment was found to interact negatively with the flow, resulting in a super-elevation that dissipated much of the available priming energy. The paper presents the novel solution used in place of a costly pipeline realignment, as well as questions to be considered during future self-priming siphon designs.

In semi-arid environments, rivers are often characterized by intermittent flows that may have high sediment concentrations. In such cases, dams forming storage reservoirs may be developed at off-stream locations having small watersheds, with inflows being provided from a nearby river via a diversion dam and supply canal. This design limits the sediment inflows to only those from the watershed above the reservoir and those carried by the supply canal from the source river, lengthening the life of the reservoir. Sediment concentrations in the supply canal may be reduced by desilting facilities at the diversion dam, and possibly along the canal as well. This paper presents an analysis of strategies that were considered for managing sediment inflows to a supply canal for a proposed off-stream reservoir. An unexpected finding is that a sediment trap basin, which had been proposed to be located along the supply canal, could reduce, rather than improve, the overall sediment removal efficiency of the diversion-supply system. This outcome is due to a lack of sufficient water in the source river to sluice sediment deposits from both the diversion dam pool and the sediment trap basin. This study illustrates how, in cases of scarce water supplies with high sediment loads, there can be tradeoffs between the differing needs for managing water and sediment.

Numerical modeling of the Middle Rio Grande River from Cochiti Dam to the Narrows of Elephant Butte will be used to guide future river maintenance planning. Six strategies - which define reach-scale management approaches - have been formulated to more holistically integrate river maintenance actions with the physical processes occurring on the Middle Rio Grande. Several analyses were performed to help estimate the effects of implementing these strategies. A mobile bed model was employed to help understand the balance between sediment transport capacity and sediment supply of each reach. The results of the sediment routing model provide for each reach a likely future equilibrium slope, change in bed elevation, and change in bed sediment size. The hydraulic modeling provides, by reach, hydraulic characteristics for the representative flow of 4700 cfs and an assessment of very high flow capacity for strategy geometries. The meander belt assessment is a comparison of the sine-generated curve meander belt after strategy implementation to the existing lateral constraints in a reach. It provides information on how well a meandering channel will fit within the lateral constraints of a reach. Twenty descriptive indicators have been defined to help compare physical properties of a reach after strategy implementation. Reach specific indicator values for each strategy are developed from the modeling results. These indicators values are further classified into similar groupings, or bins, such that those that vary about a mean are classified together and those that are significantly different are identified. The groupings, or bins, are initially defined based on the standard deviation of the values, and then professional judgment is implemented where necessary. The indicator values documented in this report were used to help assess the effectiveness of strategies by reach at an appraisal level and helped identify which strategies for a given reach should be further studied in more detail.

Boundary shear stress plays an important role in momentum and mass transfers, but it is very difficult to determine experimentally. This paper develops a new method which can evaluate the boundary shear stress using the main flow data based on Momentum Balance Method (MBM). A theoretical relationship between the boundary shear stress and parameters of main flow region is established. The obtained results from MBM agree well with other methods, indicating that the new method is reasonable and reliable. The significant contribution of MBM is that the local boundary shear stress accurately and quickly can be determined by application of this new method . Hence, MBM may provide a useful tool for hydraulic engineers who need a simple and easy way to measure the boundary shear stress.

The objective of the present research is to provide a more comprehensive hydraulic analysis of flow pattern around emergency spillways of the levee systems and also recommend an optimum pattern for installation of fuse plug spillways. The design of fuse plug spillways is usually based on very simple assumptions or 1-D models which neglect the influence of flow pattern around a fuse plug spillway on the neighboring spillways. These assumptions may lead to improper design of a set of emergency spillways. Application of 2-D models is highly recommended for the assessment of those effects. In this study, MIKE21 is used as a 2-D model to study the flow pattern around a set of fuse plug spillways. MIKE21 model is based on numerical solution of 2-D depth averaged Navier-Stokes equations. The modeling results are used to recommend the optimum pattern of fuse plug spillways. The results also show that installation of separate spillways decrease the total outflow about 1.01% to 1.35% compared to single a spillway. As a case study, Helleh River in Iran was considered. Several patterns for fuse plugs were modeled and the optimum pattern was selected based on economic and technical criteria. The influence of the flow patterns around each spillway on the neighboring spillways and the flood propagation on dry bed in the flood plain are presented as graphs and animations. The results of this study demonstrate the performance of MIKE21 for these types of the modeling and also may be helpful for designers of the flood protection levees in similar cases.

Increasing water discharge to account for a high concentration of sediment in the flow is known as bulking. Although bulked flows are intrinsically non- Newtonian, it is common practice for flows with bulking factors up to 2.0 to be modeled with HEC-RAS or other standard hydraulic models. Thus, there is a critical need to develop the best methods of utilizing HEC-RAS for debris/mud flow event modeling. In response, an algorithm was developed that utilizes similitude to modify the normal input parameters in a way to account for the bulked flow effects and hence maximize the accuracy of the developed HEC-RAS model. The method is presented, and the results are discussed in terms of potential applications, the implied limitations, and the need for further research.

Dam-breach flood analyses rarely take into account the uncertain nature of numerical model parameters when assessing the flood hazards of potential failures. Solution uncertainty is evaluated here using a point-estimate method that provides a direct and efficient computational procedure to obtain moment estimates (specifically, the means and variances) of calculated peak water-surface elevations, peak discharges, and flood peak travel times. The method is applied to Big Bay Dam to define bounds on downstream flood hazards having specified pexceedance probabilities. Comparison to peak water-surface elevations that were produced by actual failure of the dam shows the approach to provide a reasonable estimate of downstream flood hazard uncertainty.

Potential effects of large woody debris accumulations on backwater, hydrodynamic loads on structures, and local scour at bridge piers along a section of an urban stream containing three bridge crossings were modeled using the computer program FST2DH. The two-dimensional depth-averaged flow solutions provide reliable estimates of water velocities and depths, which were used to internally calculate pressure flow and potential scour depths and hydrodynamic drag forces and impact loads on bridge piers. The effect of debris accumulations on water-surface elevations during high flows was found to be comparatively small compared to other factors such as bridge pressure flow and roughness. However, hydrodynamic drag forces acting on the blockages lead to significantly larger loads on piers. Although drift accumulations actually reduce the speeds of flows approaching piers, the most significant effect of debris accumulation on piers in this project setting is to significantly increase local scour depths. Additionally, reduced approach velocities at piers may be accompanied by increased velocities between piers, which could further increase overall bed scour.

A one-dimensional flow and sediment transport model (Sedimentation and River Hydraulics- one dimensional, SRH-1D), was expanded to incorporate and assess riparian vegetation in the flood plain. The combined flow, sediment transport, and vegetation model SRH-1DV includes a ground water and vegetation module linking ground water fluctuations (in response to river flow) and the growth and removal of vegetation to geomorphic processes of river hydraulics and sediment transport. The various components of SRH-1DV were calibrated to measured data on the Sacramento River. Modeled flow was calibrated to the water surface elevation between gaging stations, and ground water was calibrated to well data. Sediment transport was calibrated to gravel bedload measurements at the Hamilton Bridge gaging station on the Sacramento River, but ultimately sediment transport computations were not used in the simulations. Cottonwood germination, growth, and removal were simulated for the Sacramento River from RM 300 to RM 150, including Red Bluff to Colusa. Data from two field studies (2005 and 2006) of cottonwood growth on sand bars at three sites were used to calibrate the cottonwood model and improve cottonwood desiccation methods. In a second round of simulations, the Sacramento SRH-1DV model was expanded to multiple vegetation types. Cottonwood vegetation was validated using repeat vegetation mapping from 1999 and 2007, and four additional vegetation types: mixed forest, Gooding's black willow, narrow leaf willow, and the invasive plant, arundo, were calibrated with the 1999 and 2007 vegetation mapping of the Red Bluff to Colusa Reach (RM 250 to RM 143). Based on results, the arundo vegetation type was eliminated. Narrow leaf willow and Gooding's black willow proved to be successful indicators of riparian lands in model simulations. Model simulations of cottonwood forest and mixed forests also compared well with mapped results when combined.

A two-dimensional mobile-bed numerical model, SRH-2D v3, is used to evaluate a 10-year channel morphology of an 18-mile river reach upstream of the Elephant Butte Reservoir on the Rio Grande. Two scenarios are considered. One assumes that no temporary channel was excavated following the lowering of the reservoir pool; another assumes that a temporary channel was excavated instantly before the modeling period begins. The model simulation is carried out using the actual flow hydrograph from October, 2000 to June, 2010. The study aims to (a) determine the most likely channel morphology in 2010 had the temporary channel not been excavated and (b) help understand the impact of the temporary channel on the river morphology within the study reach. It is found that (a) no competent channel, similar to the excavated temporary channel, would form, had the temporary channel not been excavated; (b) the new predicted channel morphology is mostly in the form of a multi-channel type in 2010; and (c) the study points to the need for continued maintenance of the temporary channel at selected locations.

Stepped spillways are one of the main energy dissipaters in hydraulic structures. In this paper, a numerical modeling of the flow over different forms of stepped spillway has been developed and the results were compared. The base model was calibrated with experimental data. The computational fluid dynamics model which solves the RANS equations coupled to a surface-capturing algorithm to predict the main features of flow water. This included the determination of water surface, the development of swirling flow, and resulting pressures over the steps. The model was developed using the volume of fluid (VOF) method. In this paper, flow velocity at the end of spillway, and energy dissipation rate were compared in different height of steps. The RNG model of turbulence with wall functions was used to compute the eddy viscosity. Also Structured hybrid grids were used to accommodate the geometry of the stepped spillway included upstream, steps and downstream. Agreement between numerical results and experimental data showed that RNG turbulent model and VOF method for predicting the water surface in the stepped spillway were suitable. This study indicates the capability of a numerical model using the VOF technique to predict the flow variables over the complex stepped spillway.

The Mississippi River and Tributaries project performed as designed during the historic 2011 Mississippi River flood, with many of the operational decisions based on discharge targets as opposed to stage. Measurement of discharge at the Tarbert Landing, Mississippi range provides critical information used in operational decisions for the floodways located in Louisiana. Historically, discharge measurements have been made using a Price AA current meter and the mid-section method, and a long record exists based on these types of measurements, including historical peak discharges. Discharge measurements made using an acoustic Doppler current profiler from a moving boat have been incorporated into the record since the mid 1990's, and are used along with the Price AA mid-section measurements. During the 2011 flood event, both methods were used and appeared to provide different results at times. The apparent differences between the measurement techniques are due to complex hydrodynamics at this location that created large spatial and temporal fluctuations in the flow. The data and analysis presented herein show the difference between the two methods to be within the expected accuracy of the measurements when the measurements are made concurrently. The observed fluctuations prevent valid comparisons of data collected sequentially or even with different observation durations.

A critical evaluation of two physically based variable parameter Muskingum methods, viz., the variable parameter Muskingum-Cunge (VPMC) method advocated by Ponce and Yevjevich (1978) and improved by Ponce and Chaganti (1994), and the variable parameter McCarthy-Muskingum routing (VPMM) method recently developed by Price and Perumal (2011) is made in this study. The evaluation is made by routing a given hypothetical inflow discharge hydrograph in uniform rectangular and trapezoidal channels using these two methods and comparing the routed hydrographs with the corresponding hydrographs estimated using the full Saint Venant equations, which form the benchmark model. The routed hydrographs arrived at by these two methods at the outlet of 40 km channel reaches were compared with the corresponding Saint Venant solutions using different performance criteria. The study reveals that the VPMM method consistently performs far better than the VPMC method, and is applicable for a wide range of flow and channel conditions. Moreover, the VPMM method is fully volume conservative, whereas there is significant volume error while using the VPMC method. Further, this study reveals that while routing a kinematic wave in smaller routing reaches, the theory of the matched diffusivity interpretation for the Muskingum method for estimating the values of weighting parameter, θ ≈ 0.5, is not consistent with the matched diffusivity concept. Hence, this clearly calls for a rethinking on the theory behind the development of the VPMC method.

The present study focuses on understanding the flow dynamics of baffled disinfection contact tanks through the use of computational fluid dynamics (CFD). In particular, we seek to address the key question: for a given footprint of a contact tank with a fixed inlet configuration, how does the hydraulic efficiency of the tank depend on the configuration of internal baffles? The benchmark contact tank geometry in our study is shown in Figure 1. In order to define guidelines for hydraulically efficient baffle tanks, we perform a total of 36 high-resolution three-dimensional simulations to quantify the efficiency of a laboratory scale tank as a function of the dimensional relationships between the inlet width, channel width, tank width, tank length and baffle opening length. Simulated flow through curves (FTC) and longitudinal velocity profiles show good agreement with previous experimental results. Our analysis of residence time distribution (RTD) curves obtained for different tank configurations of the same footprint indicate that an optimum configuration that approaches near plug flow conditions may exist and can be defined by the dimensional relationships examined in this study.

Stream bank erosion can be an important form of channel adjustment in unstable alluvial environments and hence should be accounted for in geomorphic studies, river restoration, dam removal, and channel maintenance projects. Recently, one-dimensional and two-dimensional simulation models have become useful tools for predicting channel responses; but most either ignore bank failure mechanisms or implement only simple ad hoc methods. In this study, a twodimensional model (SRH-2D) is coupled with a deterministic bank stability and toe erosion model (BSTEM) to predict channel adjustment and planform development. Herein, the proposed coupling approach is described, along with numerical aspects of the procedures. For test and verification purposes, the coupled model is used to predict bank retreat of Goodwin Creek in Mississippi. A comparison of the model results with the measured data is presented and discussed.

Current culvert design standards for fish passage compare sustained swimming abilities of the target fish species with a cross sectional area based average flow velocity through the culvert. Such policies dictate relatively large culvert barrels and do not recognize the significant role of reduced velocity zones in the culvert near boundaries. Tests of the upstream passage success of several sensitive native Utah fish, namely leatherside chub (Lepidomeda aliciae), longnose dace (Rhinichthys cataractae), and speckled dace (Rhinichthys osculus), was conducted in an experimental flume and in a southern Utah stream (Salina Creek). The laboratory flume tests were conducted using leatherside chub and longnose dace and three different boundary conditions: (1) a smooth boundary, (2) a smooth boundary with strategically placed cylinders, and (3) a boundary consisting of natural substrate. The key finding from the laboratory test was that substrate that scaled with the fish length required the least energy expenditure, provided sufficient refuge for the fish to behave naturally, and allowed for successful fish passage. This finding was tested in the field by comparing fish passage rates of leatherside chub and speckled dace through three types of sites: (1) an arch culvert with a coarse substrate bottom, (2) a double barrel box culvert with a smooth bottom, and (3) a section of stream with a length similar to the two culverts. Results show an increased rate of upstream passage through the stream section and arch culvert when compared to the box culvert, especially among the leatherside chubs. Velocity measurements were taken near the bed at each site and were compared to measured fish swimming velocities and used to characterize the amount of variation in velocity near the substrate. If rock substrate with known near boundary velocities could be used to retrofit existing culverts and design new culverts it would lower costs and result in fewer culvert replacements and less obtrusive designs.

A review of previous and current modeling studies is presented to support the selection of the Finite Volume Coastal Ocean Model (FVCOM) as the hydrodynamic model driver within the National Ocean Service (NOS) operational forecast system for San Francisco Bay (SFBOFS). This review will also focus on the validation approaches used and available datasets. In addition, the present NOS forecast model construction process is outlined in terms of grid development considering two separate grid regions: 1) San Francisco Bay and the near shelf, and 2) offshore region to include the National Marine Sanctuaries. The specification of the offshore boundary conditions (to enable future couplings to a NOS West Coast shelf model) is discussed along with the development of initial conditions for hindcast validation. Initially, two-month simulation validation plans are presented utilizing the restored joint NOS and USGS 1979-1980 historical circulation survey datasets to calibrate the model for astronomical forcings. Next, extended hindcast plans are discussed to further validate the model for astronomical and complete meteorological forcings. The transition of SFBOFS to formal operations is outlined with plans for additional validation efforts and ongoing skill assessment.

Settling velocity of wastewater grit is a major concern in the design of grit removal devices. However, settling velocity is difficult to quantify for the size of particles encountered at wastewater treatment works. The goal of this project was to take existing settling velocity techniques and optimize the design to take samples of particles of known settling velocity. The developed technique was then validated and applied to wastewater grit samples to determine their settling velocities. The particles from each sample were analyzed with a high speed imaging system that collected information on the size, shape, length of the particles and other characteristics of interest. This paper outlines the process that was used to develop the settling velocity methodology. Five different setups were tested before the final design was chosen. The different concepts tested are described along with the pros and cons of each setup. In the end the final design was a long, wide column with a central sampling point close to the bottom that is used to sample material within a given particle size range. The sampling time was based on the theoretical settling rate for clean spherical silica particles within the range of interest. The setup developed was then used to characterize the settling characteristics of samples taken from three wastewater treatment plants in the United States. The results from the analysis show that wastewater grit has different settling characteristics when compared to clean silica sand.

Common carp (Cyprinus carpio) is a major and widespread pest species in southeast Australia. The recent emphasis on the restoration of environmental flows to natural waterways has emphasized the issue of preventing the movement of carp into currently carp-free areas while permitting the passage of major water flows. Biological control techniques are still many years away from effective implementation. In the meantime, the use of engineered structures represents an important mechanism for the exclusion of carp. This paper presents a case study of a non-discriminatory structure. This structure was shown, through a physical model study, to be very effective in capturing better than 97% of introduced samples of carp eggs and carp fingerlings while passing unrestricted water flows.. Of the less than 3% that passed through the structure, 10% - or less than 0.3% of the total introduced sample - was considered viable. Following the success of the model study, a prototype structure was built. Monitoring results from the prototype structure support the model predictions.

In relatively flat zones meandering rivers generally form due to alternately eroding sediments in outside of the bend and deposition on the inside. The width of the formed bends decreases through the bend in natural meanders. Convergence rate has a considerable effect on flow pattern and the developed spiral flow. This investigation is conducted to predict flow pattern in 90 degree bend under rigid bed for different convergence ratio (0.5, 0.75, and 1) using SSIIM simulation model. The numerical model verified and calibrated by the obtained experimental results. Velocity profiles and bed shear stresses are estimated using SSIIM simulation model for each convergence ratio. The results show that velocity profiles and location of maximum velocity are closely depending on convergence ratio.

The problem of prediction of resistance to flow in open channels has attracted the attention of hydraulic engineers for a long time. Over the last few decades, the Nikuradse's concept of an equivalent sand grain roughness size has been successfully used in a wide variety of problems involving hydraulic resistance to flow. However, when it comes to practical implications such as vegetated flows, where the relative spacing, size and shape of the roughness elements are particularly important features, then the use of an equivalent roughness size becomes problematic because of the non uniformity of the boundary roughness. To overcome this problem, many researchers have investigated extensively using artificial roughnesses on the channel boundary, to predict the friction factor in rigid boundary open channel flow. By drawing analogies between skin friction and form drag, this study proposes a new friction factor function based on the roughness density. This new formula has been verified using data acquired from several flume experiments, carried out for flow fields with vegetation simulated by artificial cylinders. Results indicate that, for a given geometrical shape, the maximum friction occurs at a particular roughness density, when the bed is fully covered by large eddies. After this the flow resistance starts to decrease irrespective of the increase in roughness density. This variation should be quite similar in all the cases of geometrical shapes of roughness elements. Further this method provides a useful basis for practicing engineers to calculate the friction factor in vegetated flows, flow around bridge piers, etc. It also assists in the determination of when the maximum friction would occur, developing a significant step towards the better understanding of the resistance mechanism.

Riverine bendway migration is a function of the shear stress exerted on the bendway banks and channel geometry. The ratio of shear stress in a channel bendway to the straight channel approach shear stress (K_b) provides an indicator of bendway migration. Current procedures for predicting K_b values were derived from shear stresses measured in rigid, trapezoidal-shaped channels (K_b ranges from 1.05 to 2.5). A model study was conducted in a rigid bed channel with natural planform, thalweg, and cross sections derived from field surveys. The K_b values derived from this study (Preston Tube) were compared with existing procedures for predicting K_b. Using measured peak K_b values (high magnitude, non-sustainable, short duration), K_b ranged from 5.7 to 10.9 times higher than prescribed procedures. A HEC-RAS simulation was also performed yielding K_b values of 1.5 to 2.78 times higher than established K_b predictions. K_b values derived from channels with natural planform, thalweg, and roughened surfaces significantly increase the design K_b thresholds to assure bank stabilization.

The technique of submerged vanes is a new and efficient sediment management method in rivers. This method has positive environmental effects. The performance and efficiency of a submerged vane is related to its shape. In the present study, physical hydraulic model testing is performed to investigate four shapes of vanes: a simple rectangular vane, and three vanes that are beveled at leading edge in 30, 45, and 60 degrees with respect to the base, respectively. The experiments show that cutting the leading edge of the vanes reduces the local scour around the vanes. Maximum scour depth reduction occurred due to the maximum chamfer at leading edge of the vanes. Based on the results, cutting the leading edge of the vanes is a performance improving and also cost saving modification, too.

Water pipelines have an important role of connecting key components such as purification plants and reservoirs and tanks. While these components are designed to operate in pressurized flow mode, under abnormal operational conditions air phase may be present within the conduits, particularly in the form of entrapped pockets after refilling operations. While past investigations have addressed issues related to surges caused by air pocket compression and the removal of discrete pockets by means of drag, the development of numerical models to simulate refilling considering effects of air phase is still an outstanding issue. With the objective of providing data for the development of numerical models to describe pipeline filling accounting for air pressurization effect, a systematic experimental investigation was conducted whereby various flow conditions were tested. Results indicate that air pressurization degree can affect significantly the filling process, including generating complex air-water flow interactions such as interface breakdown.

The flow characteristics around a partially buried short cylinder on a simulated laboratory river bed were examined experimentally and numerically. Experiments were conducted in a 50 m long tilting flume with vertical walls made of acrylic plastic and steel floor covered by a 24 m long sand pit, at high Reynolds numbers. After the burial and the scour pattern around the object reached equilibrium morphodynamic conditions, velocity records were taken with an acoustic Doppler velocimeter (ADV) probe. The flow structure around the object was investigated using an LES turbulence closure model. The experiments and the simulations allowed establishing a spatial and temporal correlation between shear stress levels, turbulent kinetic energy (TKE), and the resulting scouring activity that leads to the burial and the scour hole topology around the object. The LES closure allowed studying the highly unsteady coherent turbulent structures generated not only by the object but from the surrounding bedforms. Herein, only the numerical results are presented.

This study examined the influence of riparian vegetation patches with multiple layers (combination of grasses and herbaceous plants) on flow complexity. A flume experiment was conducted where four treatments of varying vegetation combinations were examined; vegetation treatments were composed of two factors: percent dense flexible cover and the presence of herbaceous plantings. Three-dimensional velocity was measured with a MicroADV in a grid pattern within the measurement region. The treatments with dense vegetation cover were dominated by ejection events, and velocity vectors were directed in the positive z direction. The velocity vectors between dense vegetation patches were directed in the both positive and negative z directions. Sweep events were also present in the 50% coverage treatments.

Stampede Dam and Reservoir is located on the Little Truckee River, approximately 34 miles west of Reno, Nevada. Severe waves were observed downstream of the spillway and outlet works channel causing significant erosion and undermining of the powerplant foundation. During the 1997 flood, discharges totaled 2750 ft³/s, including 2250 ft³/s from the outlet works and up to 500 ft³/s from the spillway. Three to four foot high transverse waves were observed downstream of the spillway and outlet works channel causing significant erosion and undermining of the powerplant foundation. Combined releases of 170 m³/s (6,000 ft³/s) from the spillway and outlet works are planned with new modifications to the dam. The purpose of this study was to evaluate erosion potential based on existing conditions and show possible erosion protection alternatives. This was accomplished with one and two dimensional hydraulic models as well as estimates for riprap sizing. Research was conducted to determine if any new methods could be found to evaluate erosion with strong wave conditions.

Computer-based levee breach and inundation simulations are presented for a levee district along the eastern shore of the Middle Mississippi River. The different simulated scenarios include flooding of the district starting from a northern, a western and a southern levee breach. In the study, a hybrid 1D2D flow model was used that combines a 1D model of the Mississippi River with a 2D overland flow model of the levee district. The development of the levee breach is based on an empirical dam break formulation that calculates dimensions of the breach opening from flow characteristics in the breach and the erodibility of the levee. Next, using different floodplain roughness maps a sensitivity analysis is carried out of the simulated flood events, highlighting the impact of floodplain land cover on maximum breach size, flood arrival times and maximum inundation depths. Also, a classification scheme is proposed that characterizes different flood phases. Each flood phase is associated with particular flow conditions and thus requires different types of flood mitigation strategies.

Hypoxia within lower Green Bay has been a problem for decades, and the problem may be worsening. Numerical modeling and field studies are underway to improve our understanding of circulation, thermal regime and anoxia in Green Bay. Model validation was successful because modeled currents are reasonably close to data collected at three monitoring stations. Model results showed that wind shear and circulation are stronger in winter than in summer. Water exchange between Lake Michigan and Green Bay is stronger during the summer, when wind shear is mostly axial. Mass exchange affects stratification, and possibly the development of anoxia. Results showed stable anticyclonic gyres both south and north of Chambers Island, and cyclonic gyres near the mouth of the Fox River and south of the passages between Green Bay and Lake Michigan. The former is consistent with the Fox River plume clinging to the east shore of the bay.

Waterman Wash is an un-gauged watercourse for sediment transport located in Arizona, USA. The Zeller-Fullerton (1983) equation is commonly used to estimate the channel bed material load for un-gauged sand and gravel channels in the arid southwest region of the United States. It is also regulated to quantitate channel sediment transport by the local government agencies. However, current sediment transport programs do not provide the Zeller-Fullerton equation for sediment transport computations. In this study, HEC-RAS v4.1 was selected to perform the sediment transport modeling for Waterman Wash. Two scenarios were executed for sediment transport analysis. The first scenario used sediment discharge rating tables that were based on the Zeller-Fullerton equation to estimate the sediment inflow of the tributaries. The other scenario used sediment discharge rating tables that were based on the Meyer-Peter-Muller (1948) equation. Both scenarios selected the Meyer-Peter-Muller equation in the study reach sediment transport simulation. Comparison between the results of these two scenarios shows a significant difference in the calculated sediment delivery. This could cause issues in channel management for the local government agencies. In order to perform consistent sediment transport modeling and to rationalize sediment transport management for alluvial channels, this study concludes a need of including the Zeller-Fullerton equation in the HEC-RAS program to properly perform sediment transport modeling for un-gauged sand and gravel channels in the arid southwest when the Zeller-Fullerton equation is used to calculate sediment inflow.

During the rapid filling of stormwater storage tunnels, an event anticipated to occur during intense rain events, a number of different mechanisms may lead to the entrapment of air pockets. Entrapped pockets may cause operational issues such as damaging surges, loss of storage and severe geysering upon their ventilation through water-filled vertical shafts. Most previous studies focused either on determining surges associated to air pocket compression or in obtaining minimum flow velocities required to expel entrapped pockets in water mains. However, mechanisms behind the motion of air pockets, controlled by a balance between drag and buoyancy forces, still require further investigation in conditions where ambient flow exists. Unlike water mains, inflows in stormwater tunnels cannot be fully pre-specified, and the tracking of pockets is important in the context of numerical simulation to assess the risk of operational issues such as geysering. This work presents preliminary results of an experimental investigation performed at Auburn University in which different air pocket volumes are released in pressurized closed-pipe flow at selected slopes and flow rates. Kinematics of entrapped air pockets is studied for the different flow conditions, with the goal of gaining insights on the relationship between the pocket celerity and the relationship with its volume as well to flow velocity and pipeline slope.

Fluid flow behavior in the critical zone between laminar and turbulent has remained a hydrodynamic curiosity since Reynolds' notable paper in 1883. Over the last 125 years, large efforts have been made in understanding the flow transition from laminar to turbulent states; however, remarkably less focus has been placed on the reverse transition and hysteresis in these transitions. Previous studies have shown that there is an exponential relationship (decay rate) for relaminarization of turbulence when the pipe flow is below the critical number (Re ~2,300). This paper reports initial results of two investigations: a study on the effects of hysteresis as flow is brought through the critical region, and an examination of the time dependant pressure drops (and associated friction factor) of pipe flow in the relaminarization of fully developed turbulent flow. The preliminary results of a hysteresis analysis suggest that there are lower and upper critical Reynolds numbers for the constructed system with smooth walled pipes. During the turbulence decay study, flow starting at completely turbulent Reynolds numbers (Re >5,000) was decreased back within the critical range of flows. A time-pressure relationship was recorded and analyzed, and an initial exponential decay of turbulence was observed, followed by a slow linear decay.

Two-dimensional depth-averaged flow in a section of steep, concrete-lined drainage channel consisting of an open section of trapezoidal cross section, and a covered section comprised of a four-barrel concrete box culvert, was simulated numerically using DaveF, an explicit model based on the finite volume method. Flows within most of the modeled stream channel are supercritical because of the steep slope and comparatively smooth concrete surfaces. For this reason, two areas within the box culvert exhibit abrupt large increases in depth caused by hydraulic jumps (that is, transitions from subcritical to supercritical flow). Estimates of depth increases caused by hydraulic jumps are provided by DaveF, which allows reliable conclusion to be drawn regarding the risk of creating pressure flow conditions within the box culvert.

NOAA's National Ocean Service (NOS) has supported the development of several new test beds patterned after those employed to advance meteorological forecast models. Here, we review the Integrated Ocean Observing System/Southeastern Universities Research Association (IOOS)/SURA Test Bed for the evaluation of hypoxia and coastal inundation models as a supplement to the Joint Hurricane Test Bed used to further advance hurricane track and intensity forecasting. The review will focus on present approaches toward forecast model skill assessment and improvement. Recently, the concept of a model evaluation environment has been explored within NOS's Coast Survey Development Laboratory and has been initially implemented in the Delaware River and Bay (Patchen, 2008). The restoration of NOS historical circulation survey datasets was used to provide dense spatial coverage of current, conductivity-temperature and conductivity-temperature-depth datasets for model evaluation. A set of common skill metrics was employed to compare multiple hydrodynamic models under common forcing conditions. We review these skill metrics and suggest some additional ones to further aid in the comparisons. The efforts to restore additional NOS historical circulation survey datasets are discussed in the context of the development of additional model evaluation environments in other coastal and estuarine regions. In conclusion, plans for further development of model test beds and evaluation environments are presented in the context of the IOOS goal to quantitatively assess model forecast improvements.

Numerical unsteady-flow simulations were used to investigate the breach outflow hydrographs produced by hypothetical canal embankment failures, considering the interaction of canal hydrodynamic effects and the rate of breach development. The studies led to the development of appraisal-level procedures for estimating the peak outflow rate and other breach outflow hydrograph characteristics as a function of canal hydraulic properties, breach development rate, the length of the affected canal reach, and the location of the breach relative to upstream and downstream check structures. These procedures will help water managers identify canal reaches and specific breach locations that have potential to produce large peak outflow rates.

Numerical solution of shallow water equations using an explicit scheme are generally implemented using array type data structures. The computation is performed by sweeping the entire two-dimensional computational domain in row or column-wise order, starting with the cell in one corner and ending with the cell in the opposite corner. Although much simpler to program, this technique presents an important drawback due to the fact that it does not distinguish between wet (cells containing water) and dry cells. During a simulation, a considerable amount of computational time is spent sweeping over dry cells and skipping them once they are detected to be dry. The present study introduces a new solution algorithm which computes only those cells of the computational domain that are already wet or are becoming wet. This algorithm is especially useful for accelerating computations over very large Cartesian grids when only a small portion of cells are wet. The tracking of wet cells is achieved using dynamic data structures. This implementation takes advantage of the CFL (Courant-Friedrichs-Lewy) condition for explicit schemes, which requires that the flood propagates a fraction of the cell size during a time step. The CFL condition ensures that only the dry cells that are direct neighbors of wet cells can become wet cells. A multi-threaded parallelized version of this algorithm is implemented and tested in the CCHE2D-FLOOD, which is the solver of the DSS-WISE software developed by the National Center for Computational Hydroscience and Engineering, the University of Mississippi. The paper describes the implementation of the algorithm and discusses the performance gain achieved for different ratios of wet cells to the total number of cells.

An innovative rectangular deck drain has been developed by the Texas Department of Transportation (TxDOT) Bridge Division. It fits between the deck reinforcement, does not interfere with the structural connection of the rail to the deck, and is available in two widths. An equation for slotted drains developed by Federal Highway Administration (FHWA) was adopted to model its hydraulic performance; however, the model neglects the difference between the two drain widths. To better understand and model the hydraulic performance of rectangular deck drains, a physical model was built and an extensive experimental study was performed by varying drain sizes, number of drains in series, approach discharges, cross slopes and longitudinal slopes. Measurements included a series of water depth (y) and ponding width (T) at different locations, the captured discharges and bypass discharges. Applying the adopted slotted drain model to the experimental data predicts more conservative drain length than the drain length in the experiments. An accurate prediction model has been developed based on the weir equation. The model demonstrated the capture discharge is related to the drain size (L+W), the number of the drains (N), the Manning's coefficient (n), the water depth of approached gutter flow (y), the longitudinal slope (S₀), and the cross slope (S_x). Rating curve for each individual drain is the same when the drain size is 4 by 8 inches; however, it is decreased slightly along the flow direction when the drain size is 6 by 8 inches.

Research was conducted to evaluate various embankment protection techniques suitable for frequently flooded embankments and recommend the best solutions for a variety of flow conditions. Bituminous pavement, open-cell articulated concrete block, and riprap were three protection options considered. The prototype installations were placed on three different sections of highways. Major flooding was anticipated at these locations in the spring of 2011, so flow depth recorders were installed prior to the flood arrival. Velocity measurements over the embankments were taken manually during the overtopping event. The depth data was used to calculate flow velocities over the embankment using a broad crested weir relationship to calculate flow and a modified Manning's equation to calculate velocity. This research suggests the most cost-effective, low maintenance embankment protection methods are open-cell articulated concrete block and riprap, depending on the anticipated velocities. The highway can be re-opened to traffic as soon as the flood waters recede.

In 2002, the City of Bellingham, WA began seeking a solution to the dilemma about how to restore fish passage at the site of their diversion dam on the Middle Fork, Nooksack River. The problem was created when the diversion dam was constructed in 1960-61 with no provisions for fish passage. Different options for resolving the fish passage problem were considered over the intervening years by the City and are discussed in this paper. These options included the addition of a fish ladder to the dam, and a river engineering concept that would have allowed the dam to be partially removed and river water diverted through a new intake structure. These previous concepts failed for various technical feasibility and economic reasons. The City's search for a feasible solution has now turned to consideration of a siphon-based diversion system coupled with a partial removal of the dam. The current status of the siphon option is discussed.

Droughts in the 1880's, the 1930's, the 1960's and the 1980's have been the basis of design for the water supply systems in New Jersey. But as demand exceeded the available supply, reservoirs constructed to store runoff from 300 square miles had to be augmented by pumping stations that skimmed water from an additional 500 square miles. However, even that was not enough to preserve storage during droughts that occurred from 1990 to 2002. Consequently, the purveyors had to operate those systems under emergency conditions based on State regulations. This paper provides an historic and more recent analysis of rainfall runoff trends to determine if those emergency operating rules would be sufficient if present trends continue or if new facilities are needed. The results are ambiguous, because the median trends tend to increase at the same time as frequency and magnitude high and low flow in each subwatershed changes differently. From a drought management perspective, one critical question is, "Would pumped storage systems be capable of skimming enough in the future?". The operation of pumping stations to refill reservoirs is the single most important strategy in drought management in New Jersey. As such, the frequency and magnitude of streamflows, in the range of 200 million gallons per day (mgd) to 500 mgd, especially in the Spring, becomes critical. Since Hurricanes and northeasters have occurred in the last 10 years, one might assume there is plenty to skim. However from a multi year perspective -high flows will be followed by low flows as nature reverts to a mean over decades. From that perspective, if the rainfall during the past 10 years averages 55 inches , the probability that rainfall would average 37 inches during the next ten years increases as long as the long term mean for New Jersey is an average annual rainfall of 46 inches. Therefore, even if long term trends increase, a shorter term evaluation remains appropriate. In this instance, a trend analysis before 1970 and after 1980 indicates design, operation and management of the pumped storage water supply system may have to change. An initial finding was that more pumping may have to occur in the Fall and Winter since streamflows in the Spring are decreasing.

A 2D numerical model based on shallow-water equations is used for rainfall-runoff modeling. The rainfall intensity and infiltration rate are added as source and sink terms in the continuity equation. The Green-Ampt method is used for calculation of the infiltration rate. The model considers the spatial variability of rainfall, infiltration parameters and the Manning's friction coefficient. The GIS layers such as DEM, soil type, and land use can be directly used as input for the model. Spatio-temporal distribution of the rainfall over the watershed is determined based on rain gauge records. The model is applied to Goodwin Creek experimental watershed located in northern Mississippi. The model parameters are first calibrated using a single storm event. Using the calibrated parameters, the model is then applied to a serried of consecutive storm events. The comparison of computed and measured runoff discharge at the outlet of the watersheds shows good agreement. The results of this study indicate that this model can be used for modeling rainfall-runoff in large watersheds based on a historical or predicted rainfall distribution.

The selection of an appropriate design discharge that best approximates the channel forming discharge is critical to channel design and dictates the success of restoration projects in improving channel stability. Channel forming discharge is defined as the theoretical discharge that if constantly maintained in an alluvial stream over a period of time will produce the same channel geometry that is produced by the long-term hydrograph, and it is often estimated as the bankfull, effective, or recurrence interval discharge. The determination of the channel forming flow often focuses on the physical and erosional characteristics of the stream at a reach scale (analyzing sediment transport characteristics or identifying bankfull indicators). However, with wide variability in streamflow and flood timing across regions, it is critical to examine hydrologic and watershed characteristics and their relationship to channel forming flow. Obtaining a good estimate of the channel forming discharge requires looking beyond the reach scale and gaining an understanding of regional watershed hydrology and runoff characteristics (e.g., rainfall, snowfall, geology, soil type, land use, basin topography). The purpose of this work was to conduct an investigation to determine relationships between channel forming discharge and hydrologic and watershed characteristics for snow-melt dominated streams in Wyoming and Colorado. Significant relationships between bankfull/effective discharge and watershed and hydrologic characteristics were determined. In particular, it was determined that certain characteristics directly related to snowmelt hydrology and runoff (e.g., drainage area above 9000 ft and snow water equivalent) are most significant in estimating a channel forming discharge. The results of this study provide regional characteristics of snowmelt dominant systems that are important when determining a design discharge for stream restoration projects.

In gravel bed rivers, the flow resistance is mostly due to grain roughness. Strickler was the first who determined the grain roughness coefficient in terms of sediment particle size. In the so called Strickler's formula, the Manning's coefficient has been related to only the median particle size ( n = cD_S^1/6 ). Therefore it is the purpose of this study to conduct experimental test to find out if the same sediment size but in different shapes, can produce different flow resistance and if so by how much. To reach such goals four different sizes of round sediment particles taken from natural river bed and four crushed sediment particles with the same sizes as river bed sediment were tested under constant flow conditions. The experimental tests were conducted in a 12 meter long flume of 25 centimeter wide. The energy gradient between the upstream and downstream stations was calculated by Bernoulli's equation. Then the roughness coefficient was computed using the Manning's formula. Comparison of the data shows that the particle shape can affect the particle roughness. The results also have been compared with the Strickler's type of equation and the best relations have been developed.

The Arroyo Seco Watershed Assessment (ASWA) provides a framework for the integration of transportation, energy, water resources and restoration concerns in the development and rehabilitation of the Arroyo Seco Watershed, a subwatershed of the Los Angeles River Watershed. The framework culminates with top tier restoration projects spanning the entire watershed from the crest to the confluence with the Los Angeles River, as follows. The Upper Arroyo Seco Channel Restoration is a multi-use project that extends from NASA's Jet Propulsion Lab (JPL) upstream to the watershed divide that will improve water supply, recreation, water quality and ecosystem health. The project is a culmination of years of grassroots planning efforts and analysis focusing on southern California ecosystems. Upstream of JPL, the primary habitat disruptors are impediments to fish passage, forage, rearing and spawning, including anthropogenic structures such as road crossings and water supply diversion and flood control dams. The Central and Lower Arroyo Restoration projects will continue aquatic and upland habitat restoration efforts. Meandering through neighborhoods along the Arroyo Seco, the Lower Arroyo linkages will provide safe pedestrian and cycling links in the highly urban lower reaches of the watershed. ASWA implementation will involve restoration of endangered riverine and upland ecosystem communities, including Riversidian Alluvial Fan Sage Scrub, Southern Sycamore Riparian Woodland, Streambed Riparian, Mule Fat Scrub, Southern Willow Scrub and Coast Live Oak Woodland. Native fish restoration is a key driver for watershed protection efforts and inter-agency cooperation.

Stability of loose rock riprap used to protect stream banks from erosive forces due to flowing water is evaluated based on the ratio of static moments resisting overturning and those promoting overturning of a single rock particle. The ratio of moments defines a safety factor that describes the potential for riprap failure. The buoyant force acting on a particle is treated separately from the gravitational force, and is further split into components that resist and promote overturning. This approach provides consistency in reasoning throughout the formulation, which results in a particle safety factor that tends to unity as rock specific gravity approaches one. The safety factor formulation is tested using 38 onsite measurements of riprap-lined stream channels that have experienced floods approaching or exceeding the flow rates used to design the protective covers. Based on skill score assessments, the approach is shown to be a significantly more reliable riprap damage predictor than two other commonly used methods.

Streambed sediments play a prominent role in sediment transport loads and stream biogeochemical cycling. This study focuses on assessing streambed dynamics as a result of hydrologic and hydraulic variability in a lowland agricultural watershed within the Bluegrass Region of Central Kentucky. The influence of hydrologic events and their resulting hydraulic forcing on sediment is explored with respect to bed depth using sediment transport modeling and validated using field measurements. Modeling of streambed and sediment transport processes was extended to stream biogeochemical cycles including a particulate organic carbon (POC) and nitrogen transformation subroutine. Results of the study show that the streambed experiences long term equilibrium with respect to depth due to steady bed erosion at low flow and net deposition during large storm events. With regards to benthic sediment bed processes, hydraulic forcing of the sediment bed was found to be at least as important a governing parameter of carbon and nitrogen transformations as more traditionally accepted environmental variables, i.e., water temperature and chemistry. This sediment transport contribution emphasizes the need for stronger coupling of hydraulics and sediment transport modeling with stream biogeochemistry modeling.

While most fish passage analysis, retrofit, and design have been focused on imperiled anadromous species in states along the coasts, in Midwest watersheds such analysis has not historically been viewed as a primary concern to regional water policy. This is due, in part, to the assumption that there is not a migration (or connectivity) problem since there are not any large migratory keystone species. However, it's anticipated that a significant fraction of Midwest culverts cause impacts to fish movement, and the goal of this research is to determine the percentage of culverts that are barriers to fish passage in this region. To assess the passage rates of native fish species in existing Midwest culverts, the research team used regional databases, GIS tools, and two fish passage analysis programs to determine the percentage of culverts in Northeast Ohio that are barriers to fish migration. Ohio Department of Transportation supplied a database of existing highway culverts containing 5,837 culverts; it was determined that 169 culverts had enough information (material, slope, diameter, shape), sufficient diameter (>24 inches), a discernible channel geometry, and circular shape (simplified analysis for this first assessment) to predict fish passage success rates. At present results of 55 culverts have been analyzed using FishXing and one culvert using an add-on HEC-RAS code that predicts fish passage. Results from the analysis using FishXing indicate that none of the selected fish species was able to pass upstream through any of the culverts during the 2 year flood, two of the fish (Greenside darter and Golden shiner) were able to pass on average 3% of the culverts during highest average monthly flow, two of fish species (Greenside darter and Blacknose dace) were able to pass on average 25% of the culverts during the minimum average monthly flow, and on average 13% of the culverts during the typical low flow day (25% low flow). Results obtained with the HEC-RAS tool showed only moderately better passage conditions, with the main cause for the barrier being excessive velocity, in spite of the streams' moderate hydraulic gradients. While additional analysis of the remaining culverts is necessary, both the method outlined and the results are expected to be useful in aiding fish passage analysis and design.

This study uses an integrated coastal processes model to simulate hydrodynamics driven by storms, tides, river inflows, and winds in a large-scale domain covering the Mississippi and Louisiana Gulf Coasts. By using existing bathymetric data and DEM topographic data, a high-resolution mesh is generated to represent structures, roads, rivers, barrier islands, and lakes. For study of flooding and inundation of hurricanes in the inland areas of the Mississippi Gulf Coast, the Pearl River and its floodplain are included in the mesh with a detailed river course. Using two synthetic storms, four hurricane scenarios are simulated by using this model. Computed maximum storm surges without the Pearl River are compared with those with the river inflow. Differences between the storm surges indicate that the inclusion of the river inflow is imperative in order to obtain accurate predictions on flood and inundation due to storm surges in the Mississippi Coast community.

The Metro Wastewater Reclamation District (district) provides advanced secondary treatment of Denver area wastewater via its 830,000 cubic meters per-day (cmd) Robert W. Hite treatment facility (RWHTF). RWHTF effluent is discharged to Segment 15 of the South Platte River, which extends 42 kilometers from the Burlington Ditch headgate north to the river's confluence with Big Dry Creek near Fort Lupton. In Segment 15, gravel mining operations, water supply development and irrigation diversion dams have created barriers to fish migration and the possible reduction of fish populations due to flow diversion. Modifications to the river channel have replaced much of the natural aquatic habitat with steep, armored banks to prevent erosion and sharply reduced diversity in riverbed structure. The river flow regime is highly regulated by water storage and diversion facilities. Low flows are dominated by the discharge of treated wastewater effluent from the district's RWHTF. Studies conducted by the district and CDM Smith in the 1990s to support the adoption of a site-specific dissolved oxygen (DO) standard for Segment 15 revealed that overall, habitat quality in the segment is low for indigenous fish species. Scarcity of cover, stream size, shifting sand substrate and fluctuations in flow may limit aquatic species distribution and reproductive success. These findings were confirmed by a subsequent aquatic life habitat assessment completed in 2006. Based on these studies and in accordance with agreements with regulatory agencies, the district is implementing a habitat improvements program in Reach 9 of Segment 15 (Brantner Ditch diversion to 124th Avenue). The improvements are intended to provide increased aquatic habitat diversity and channel structure through varying flow depth, velocity and protective cover. The program is being conducted in six phases starting in 2008 and concluding in 2016. Phase I included habitat improvements and bank stabilization upstream of the 120th Avenue bridge. Construction of phase I improvements started in October 2008 and were completed in April 2009. Phase II habitat improvements have been designed. This includes additional habitat improvements in the general vicinity of phase I improvements. Proposed improvements include enhancing features from the original phase II improvements identified in the segment 15 Aquatic Life Assessment Report and additional improvements based on phase I monitoring and additional field reconnaissance. Construction of phase II improvements is anticipated to start in October 2011.

The Mississippi River & Tributaries (MR&T) Project was authorized by Congress in the 1928 Flood Control Act following the disastrous 1927 flood and has thus far prevented a repeat of such catastrophic flooding while providing adequate conveyance to safely pass flood events. Despite the magnitude of the 2011 flood event, flooding was limited to the conveyance areas intended for safe passage of major floods as designed by the MR&T system. As with most major floods, public and media interest focused on the areas that were flooded, but provided only limited acknowledgement of the areas that would have flooded without the project. Despite the success of the MR&T Project, some interests have raised concerns that the flood risk reduction system has overly constricted or constrained the river and its floodplain and have suggested that more of the historic floodplain should be made available for major floods, habitat and water quality concerns. The Netherlands' "Room for the River" program consists of measures and projects designed to reopen its Rhine River floodplains to address similar concerns within their river basin. The MR&T project will be compared and contrasted to the Netherlands' program with an emphasis on the differences in scale between the two programs, with respect to the overall area and volume of water that must be conveyed by the systems. Using the 2011 Flood results, this paper compares how the MR&T project system was designed and how it functioned to provide "Room for the River" while limiting flooding impacts to the four million residents of the Lower Mississippi River basin.

This work discusses the development of the Railway Hydraulic Hazard Monitoring System (RHHMS), a flash flood forecasting system for railroad bridge and culvert crossings. Also in the report presented herein, a Geographic Information System (GIS) is used to combine national scale spatial data sets with tabular accident data available from the Federal Railroad Administration (FRA), to perform an investigation of washout-related train derailments and identify a suitable test location.

This paper presents a new framework for the intelligent control of river flooding. This framework links two components: river system routing (simulation) and optimization. The river system routing component builds upon the application of Performance Graphs (pre-computed hydraulics under gradually varied flow scenarios), while the optimization component uses the popular second generation multi-objective evolutionary algorithm Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The use of hydraulic performance graphs for river system routing results in a robust and numerically efficient model as most of the computations for the system routing only involves interpolation steps. The proposed framework allows controlled flooding in the event that the capacity of the river system has been exceeded. This controlled flooding is based on weight factors assigned to each reach of the system depending on a hierarchy of risk to losses associated with flooding. Naturally, river reaches that are less prone to flood losses are assigned smaller weight factors and reaches that are more prone to flood losses are assigned larger weight factors. For illustration purposes, the proposed framework was applied to the Boise river system in Idaho. The results show a promising outcome in the application of this model for flood control.

Although numerous at one time, southern California steelhead (Oncorhynchus mykiss) have been rare in Orange County, California waters since the 1950s. Loss of access to spawning habitat has, in part, led to the placement of steelhead on the endangered species list in 1997.Trout Unlimited (TU) and the California Wildlife Conservation Board (CWCB) have developed a comprehensive strategy to address migration barriers on Trabuco Creek created by channel modifications that prevent the fish from accessing prime spawning grounds in the Santa Ana Mountains. Remediation of these barriers includes two roughened ramp fishways that meet both California Department of Fish and Game and NOAA National Marine Fisheries passage criteria for juveniles and adults, and restoration of 700 meter of stream channel. This paper presents a description of site conditions; design criteria, including hydrologic and hydraulic analyses; fishway selection; and the stakeholder outreach process.

Metro Wastewater Reclamation District is the wastewater treatment authority for much of metropolitan Denver and parts of northern Colorado. The mechanical bar screens at the North Complex Headworks of the Metro District's Robert W. Hite Treatment Facility (RWHTF) have periodically become overwhelmed and clogged during high flow events by slugs of debris, such as rags and grease. The result of a few of these incidents has been raw wastewater spills onto the RWHTF site, with risks associated with potential discharge to the South Platte River. During a recent headworks rehabilitation project, the Metro District included the design and construction of a 230-million-gallon-per-day (mgd) passive overflow channel that would act as an emergency flow bypass around the screens and help prevent future wastewater spills. The entrance to the overflow channel is a side channel (lateral flow) weir located along one wall of the headworks influent channel. The overflow channel itself was subject to the following constraints: (1) the limited available elevation difference across the channel required a majority of the weir to be submerged at the peak design flow of 230 mgd; (2) the configuration of the headworks facility required that the downstream portion of the weir be oriented adverse to the overflow channel flow direction, which restricted the conveyance capacity of the channel; and (3) site constraints required a relatively flat channel with a steep drop end transition, which produced supercritical flow downstream of the weir location. An analytical model was developed to estimate the water levels across the weir and evaluate its ability to prevent wastewater spills. However, given the limitations of this approach, the combination of subcritical and supercritical flows in the channel, and the intricacies of the design, a physical model was constructed to aid in the final design. This paper outlines the development of the analytical model in exploring the feasibility of the proposed overflow design, the limitations of the model, the results of the physical study (including an innovative approach to address the adversely directed weir flow) and a comparison of the physical and analytical model results. The latter is presented to provide future designers guidance on the design similar structures when using analytical techniques.

Culverts are used to convey small to medium sized streams under transportation routes and are increasingly expected to maintain passage for fish and other aquatic animals. Because of excessive velocity or inadequate water depth, culvert barrels can present a barrier for fish movement. Previously culverts were designed primarily for flood conveyance purposes, but nowadays with increasing concern for aquatic ecology, culverts are being designed and assessed for fish passage purposes as well. Velocity within a culvert is a function of the cross-sectional area, slope, culvert material, and discharge. Mangin (2010) presented a review of the variation in Manning's roughness coefficient in partially filled culverts showing generally higher roughness at lower flows. However, very little data has been collected for flows less than 20 percent filled. Therefore, the aim of this research was to collect water depth under low flow conditions and develop a relation between Manning's roughness coefficient and the water depth in partially filled culverts. Since similar efforts focusing on roughness in partially filled corrugated metal culverts are underway at the Federal Highway Administration and two universities, we have focused our study on roughness variation in high-density polyethylene (HDPE) culverts. HDPE culverts are increasingly popular with road engineers due to their high strength, low cost, and low hydraulic roughness. The laboratory set up consisted of installing one of three 55 foot long culverts within a 4ft x 2ft x 60ft (W x H x L) flume. Flow depths were collected at discharges ranging from 0.2 to 9.5 cfs, at four slopes ranging from 0.2% to 2%, and in culverts of three different diameters (12in, 24in, and 42in). In total, more than 11,000 water depth measurements were collected and are reported. The analysis of the obtained data showed that the value of Manning's roughness coefficient for depths less than 20% of the culvert diameter is indeed a function of discharge, slope and diameter. The results most closely match the predictions by Pomeroy (1967), such that roughness is a maximum at 40% depth and decreases with shallower flows. These results are expected to aid engineers in the analysis and design of HDPE culverts such that they are both economical and provide adequate passage conditions for fish.

The increase in fires in arid and semi-arid parts of the Southwest U.S. has important implications for runoff and sediment management, and for the stewardship of soil-contaminated sites throughout the region. This study was initiated to examine the effects and duration of fire on wind and water erodibility on shrubland sites analogous to those on the Nevada National Security Site. Quantification of wind erosion was conducted with a portable wind tunnel analog and a small, portable rainfall simulator. Data collected on a Coleogyne ramosissima (blackbrush)- dominated site indicated post-fire windblown emissions were higher on burned compared to unburned areas, and on vegetative understory soils compared to interspace soils. By 24 months after the fire, these effects were near pre-burn levels. Water erosion, as measured by runoff response and sediment yield, was unaffected by the fire. The same measurements at a Pinus spp. (pinyon)/Artemisia spp. (sagebrush) shrubland site indicated elevated responses in the potential for both wind and water erosion 12 months after a fire. Amounts of airborne particulate material and sediment were higher from vegetative understory soils than interspace soils, while runoff was more prevalent on interspace than understory soils. These differences in wind emission and runoff data highlight the complex relationship between fire and erosion in shrubland ecosystems.

Cross flow over a submerged weir between two parallel cooling water intake flumes for a power plant is analyzed by employing spatially varied flow formulations to account for flow and submergence variability. A lateral weir is used to equalize and distribute flow between two cooling tower basins that discharge into separate intake flumes that have a common wall. The crest of the lateral weir is selected such that the desired amount of flow is diverted from one basin to the other. At the lateral weir, flow in the supplying flume decreases in the downstream direction whereas flow in the receiving flume increases by the same amount. The water level difference between the supplying and the receiving flumes is relatively small that the lateral weir operates under submerged conditions. The submergence of the lateral weir is not constant along the length of the weir but varies depending on the water level within the flumes. Therefore, a numerical technique was developed to compute the water level profile along the lateral weir iteratively by accounting the dependence of weir coefficient on the level of submergence. The method developed was found to be useful in solving flow problems related to submerged lateral/side weirs between two channels/flumes.

An electrical barrier system within the Chicago Sanitary and Ship Canal (CSSC) is considered to be critical to restraining the migration of invasive Asian carp species from the Illinois River system to Lake Michigan. The system as constructed consists of three separate barriers capable of generating electric fields meant to either immobilize or dissuade individual fish from swimming upstream. To this point there is no evidence that Asian carp have been able to successfully traverse this barrier, but studies indicate that previous operational settings may have been ineffective to prevent the movement of some fishes. This paper uses risk assessment methodologies such as event trees and the development of subjective probabilities to investigate the potential means by which fish would be able to travel upstream through the barriers and thereby access Lake Michigan and the Great Lakes. This analysis indicates that some of the foreseeable failure mechanisms are much less likely than others to occur, allowing managers to focus on addressing the more likely mechanisms. Another significant factor is that although adult fish are likely to be at least occasionally present at the barrier, it is believed that juvenile fish are not yet able to reach that location. Even though juvenile fish passing through the barrier are far less likely to establish a reproducing population than would the same number of adult fish, consideration of differential barrier effectiveness on juvenile fish suggests that a shift in operating strategies may be warranted in the future should juvenile fish be detected further upstream.

Based on the analyses of long-term precipitation data in California and Texas, recent studies by this author have shown associations between hydrological conditions in the two states and lunar orbital pathways in tandem with the earth orbiting the sun. As part of a continued validation exercise of this observation on a global scale, the current work presents a study on global hydrological teleconnection following an analysis of long-term precipitation data in the west coast United States and East Africa. The interest in this hydrological teleconnection emanates from the finding that the wettest spell in the early 1980s in the west coast United States nearly coincided with one of the worst recorded droughts in East Africa about the same time. While water year 1983 was a highly pronounced wettest year in California during the 20th century and generally caused flooding in the west coast United States, the 1984 extreme drought in East Africa caused catastrophic human and material losses. Similarly, while the west coast United States benefited from a wet hydrological condition during the recent water year of 2011, catastrophic drought conditions in East Africa have been widely reported during the same time. The analysis of available long-term precipitation data in the two regions shows inverse association that can be of prognostic value. This paper presents initial results and insights about these correlations and their associations with the lunar orbital pathways previously established for North America and modified for East Africa in order to perform this global scale analysis.

Recently, in Korea, occurrences of floods and droughts have been increased due to Drought is a normal and recurrent phenomenon. But, recurring prolonged droughts have caused consequences and diverse impacts on human system. Therefore, understanding drought characteristics is indispensable element in well-prepared drought management. This study aims to investigate the hydrological droughts of Pyongchang stream and Upstream of Namhan river in Korea. For modelling of the joint distribution of drought duration and drought severity, the copula method is used to construct the bivariate drought distribution and return period from the predetermined marginal distributions of drought duration and drought severity. As the result, the most severe droughts occurring in the period of 1967 to 2007 in the Pyongchang stream and Upstream of Namhan river, Korea were occurred in 1981 and 1973. Return period for this drought derived from the copula theory were 550 and 110 years.

This research focuses on the low flow regime of Lake Michigan watershed in the northwest Indiana, located in the southern tip of Lake Michigan. Low flow is mainly contributed through groundwater flow. Ecosystem survival depends on the low flow regime (Sala et al., 2000). Changes in landuse pattern, climate change, river training works and many other factors influences the low flow. This region had encountered lot of changes in the landuse pattern during the last 50 years. Runoff from five watersheds was used in this work. Analysis such as single station trend, regional trend, 7Q10 flow, flow duration curve and seasonal trends were conducted systematically to understand the behavior of low flow regime. Historic data such as daily flow, monthly mean temperature, monthly rainfall and land use changes were considered. To study the influence of different factors, artificial neural network based approach was used. Using relative strength effect (RSE) associated with each input neuron, the influencing factors were examined. This study indicates an increasing trend in the low flow regime for this region.

Temperature variability appears to be a major aspect as a consequence of extreme climatic changes. South Asian countries have been observing an increase in occurrence of extreme climate events in recent decades. This paper demonstrates the temporal as well as spatial variation patterns of extreme temperature conditions in the North-western region of Bangladesh, based on some temperature-related climate change indices involving Average Monthly Maximum and Minimum Temperature (Tmax and Tmin). The analysis of the paper is divided into two fold aspects. First, the average maximum and minimum temperature records from 5 meteorological stations situated in the North-western region are applied in calculating the indices, within a 30 year study period of 1971 to 2000. Then the same indices are calculated using a Regional Climate Model (RCM) temperature projections in the future time scale of 2071-2100. Comparison of these indices shows significant enhancement in temperature extremes in future times. The indices validate marked increase in Tmin value which influences the most in overall warming in North-western region both in the past reference period 1971-2000 as well as in 2071-2100. The spatial variation of these indices also shows drastic difference in the distribution of the indices in 2071-2100, compared to the climatological baseline of 1971-2000. Therefore, such simulation of indices on temperature extremes can play significant role in long-term planning for the preparedness of meteorological disasters and risk reduction in a region and to the globe as a whole.

A major dimension of climate change for south-Asia includes more erratic precipitation events, precipitation being highly intensive with large variability in individual months. Such aberrant characteristics of precipitation are gradually resulting consequences of multi-dimensional impacts. This paper demonstrates the spatial variation patterns of extreme precipitation conditions in Bangladesh, based on a precipitation-related climate change indicator called Precipitation Concentration Index (PCI). First, the monthly total precipitation records from 18 meteorological stations in Bangladesh are applied in calculating PCI within a 30-year study period of 1981-2010. Then the same index is simulated using a RCM projected precipitation values in the future time scale of 2071-2100. The spatial variation of PCI has been plotted applying GIS technique for three distinct seasons, exhibiting drastic seasonal deviations with significant regional differences between the two independent timesegments. Comparison of the two periods proves prominent increase of PCI values all over the country invariably in each season. Numerically, the RCM-based PCI denotes that precipitation during 2071-2100 might become uniform to moderately concentric in monsoon, little change of precipitation concentration is expected in premonsoon and strong irregular distribution might reach its pinnacle for dry months. Therefore, such simulation of precipitation concentration index can be effectively applied as a decision support tool for erosion and drought adaptation.

In this study, a watershed model WARMF (Watershed Analysis Risk Management Framework) was applied to the Saugahatchee Creek Watershed in Alabama to investigate hydrologic and water quality response to historical land use scenarios and potential future climate change scenarios. Based on monthly average of daily predicted values, land use changes from 1991 to 2008 led to rising pattern in nutrient levels and algal mass depleting water quality in the Saugahatchee Creek. Future climate projections for the 21st century derived from HadCM3 A2 and B2 emission scenarios were downscaled using Statistical DownScaling Model (SDSM) to local watershed scale for impact analysis. The monthly average of daily water temperature is predicted to rise and flow is predicted to decrease with warmer and drier future climate projections. Accordingly, nutrient concentrations are expected to increase. Algal concentration is predicted to increase up to mid-21st century and then decline thereafter. Dissolved oxygen concentration is predicted to fall, especially in summer. These results under different land use and climate change scenarios can be useful information for watershed planning and management decision.

A typical approach to projecting climate change impacts on water resources systems involves statistically downscaling general circulation model (GCM) or regional climate model (RCM) outputs and forcing a watershed model to evaluate hydrologic impacts. Challenges associated with this approach include properly calibrating and verifying the watershed model and maintaining a consistent energy budget between the two models. An alternative approach, particularly appealing for ungauged basins or locations where record lengths are short, is to directly predict selected streamflow quantiles from regional regression equations that include physical basin characteristics as well as meteorological variables output by climate models (Fennessey 2011). We compare the two approaches for Maumee River basin in Ohio, Indiana, and Michigan, using readily available downscaled outputs from the Coupled Model Intercomparison Project (CMIP3) as inputs to the Large Basin Runoff Model (LBRM) and Ordinary Least Square (OLS) regional regression models.

Computational models integrating the biological and physico-chemical dynamic of fluvial ecosystems with the hydrodynamics of the waterway are an essential tool for the study of the ecology of significant species and for protecting and restoring river health. This includes the prevention and control of invasive species. In this context, a 2D eco-hydrodynamic model has been developed, synthesising and adapting previous biological and physical models, the results of which describe concentrations of phytoplankton, chlorophyll, zooplankton, detritus, organic and inorganic nutrients, oxygen, benthic vegetation and the growth of zebra mussels of all size classes over time. Zebra mussel population growth is simulated according to a size-structured model. The growth of one mussel is computed according to the bioenergetic model, temperature function, mussel size and concentration of phytoplankton.

Nonlocal Lagrangian-Eulerian Fokker-Planck Equation of the kinematic open channel flow process under uncertain channel properties is developed utilizing the method of characteristics. Monte Carlo simulations showed that the developed Fokker-Planck equation is capable of modeling ensemble behavior of the kinematic open channel process under uncertain channel properties.

The main objective of the present paper is to propose a methodology for constructing the point-to-area rainfall relations in the context of climate change. In particular, a comparative study was carried out to assess the accuracy and reliability of the proposed method as compared to other existing methods using rainfall and climate data available from different sources in the southern Quebec region in Canada: observed daily rainfall data from raingages, NCEP re-analysis data, Canadian Regional Climate Model (CRCM) output, and data given by different General Circulation Models (GCMs). The popular SDSM regression-based statistical downscaling method was used to describe the linkage between large-scale climate variables given by the considered GCMs and local rainfall characteristics. Results of this illustrative application have indicated that the use of the statistical downscaling method could provide accurate point-to-area rainfall relations as compared to the observed empirical ones, while without downscaling the results given by the GCMs and the CRCM were not accurate and displayed a very high level of uncertainty.

Precipitation being a vital input for many hydrological modeling studies has a direct bearing on the water resources modeling and management at different spatial and temporal scales. According to Intergovernmental Panel on Climate Change (IPCC), frequency of extreme precipitation events is expected to increase in future with no consistent trend in mean precipitation across the globe. To evaluate trends in precipitation, Global Circulation Models (GCMs) combined with statistical or dynamic downscaling techniques are generally used. However, it is agreed that skill of any climate change model is lower for precipitation compared to that for temperature. The model performance also depends on spatial and temporal resolution of the simulations. In the current study, precipitation projections based on fifteen GCMs from WCRP's(World Climate Research Program) Coupled Model Inter-comparison Project, phase -3 (CMIP3) project with different SRES (Special Report on Emission Scenarios) runs are analyzed for the state of Florida. Historical precipitation data is used for evaluation of the models via several performance measures and for selection of the best model. Long term historical precipitation data from United States Historical Climatology Network (USHCN) and GCM simulations from 20th and 21st century are used in this study. Efficacy and utility of Bias-Corrected Spatial Disaggregation (BCSD) procedure used in CMIP3 project for downscaling precipitation data for the state of Florida is assessed. Performances of models in two distinct seasons (wet and dry) that dominate tropical climate of Florida are also evaluated.

Sea-level rise caused by global warming is posing a significant threat on the sustainable development of coastal regions in the world. Greenhouse gaseous emission generated by natural and anthropogenic radiative forcing, especially carbon dioxide (CO₂), is a most important factor to result in global warming. In this study, we propose a new dynamic control system model that explicitly incorporates impact of CO2 on global warming and sea-level rise. In the model CO₂ emission is taken as an external input acting on the system. The system is recognized using historical observations. A special emission scenario, which results in 2 oC increase of the temperature in 2100, is used to verify the model. The verified result shows that the model is effective to predict the global temperature and sea-level rise in future. We then apply the proposed model to six special emission scenarios generated by the Intergovernmental Panel on Climate Change (IPCC). Projected results indicate that the temperature increase in 2100 ranges from 1.5 to 6.0 oC and sea-level rise in 2100 spans from 59.4 to 106.4 cm relative to 1990 level. These results are highly consistent with projections by IPCC and semi-empirical approaches in recent studies.

In recent decade, the natural disasters such as flood and drought have been severely occurred in Korea and this may be due to the climate change by global warming. So, Korean government intends to develop the assessment techniques for climate change effect that will both reduce and prevent the impacts of flood and drought disasters for public security. The objective of this study is to estimate flood damage in urban drainage basin due to climate change and suggest proper flood prevention measure considering climate change. We used a GCM model of CNCM3 developed by Centre National de Recherches Meteorologiques, France and A1B, A2, B1 climate scenario for the simulation of precipitation or rainfall in Korean peninsular considering climate change. Then SWMM model was used for the flood discharge simulation in an urban drainage basin called Gyeyang-Gu, Incheon city, Korea. Based on the flood discharge simulation, the flood damage analysis was performed by using MD-FDA(Multi-Dimensional-Flood Damage Analysis) developed by Ministry of Construction and Transportation, Korea. From the flood damage analysis, we could establish the proper flood prevention measures and policy considering climate change.

This paper presents flood frequency analysis of Devils Lake, ND under current and projected future climates. A coupled distributed HEC-HMS basin model and a lake-body hydraulic model were calibrated by using both ground and NASA satellite observations. Future hydrology of the basin and lake levels were simulated using the weather samples as projected by downscaled GCMs runs under scenarios of anthropogenic modifications of the composition of atmosphere. A preliminary batch of lake-level traces was generated, and most of them have trended downward indicating a reduced expectation of flooding of the lake within the next 30 years. Candidate probabilistic distributions evaluated include Normal, Log-normal, Pearson Type-III, and Log-Pearson Type-III distributions. Because Devils Lake is a terminal lake, there was substantial serial dependence between lake levels in successive years. The expected lake-level frequencies were computed considering conditional probabilities associated with the starting level, which happens to be the highest in recorded history.

The vibrancy of a lawn is tied closely to a home's perceived appearance and value, leading many homeowners to apply quantities of nitrogen (N) fertilizer to their lawns. Application of N fertilizer to agricultural soils has been shown to release nitrous oxide (N₂O), a powerful greenhouse gas (GHG) with a 100 year global warming potential (GWP) of ~300 that can also cause depletion of stratospheric ozone. N₂O emissions from urban and suburban lawns have been measured in only a few places. Such measurements are needed to create regional GHG inventories. A method was developed to sample the soil flux of N₂O from lawns and determine quantitatively the effect of fertilization on N₂O emissions. Sampling was accomplished using closed chambers constructed of 8-inch SCH 40 PVC, deployed for 30 minutes with soil moisture and temperature monitored using time-domain reflectrometry and thermistors, respectively. N₂O concentrations were measured using a gas chromatograph with an electron capture detector. This sampling method proved useful in quantification of N₂O emissions from urban and suburban lawns.

America's cities have confronted local climate change (i.e. the "heat island" effect, and increased storm runoff) for many decades; now, global climate change presents new planning and design challenges. Because of the size of cities and complexity of urban drainage systems, planning has typically been conducted at a relatively large scale with sub-basins on the order of about 1 km². However, the most basic scale for urban hydrology is the city block, which has a scale of about 0.02 km² (approximately, 200 meters by 100 meters or 2 hectares). Urban hydrologic models have evolved to be computationally robust at this scale, and at the same time, the computer resources available to solve complex stormwater systems have exploded, allowing these hydrologic models to be solved quickly. Is it time to up the resolution of urban hydrologic modeling? Or is the current modeling paradigm sufficient?

Two major teleconnections, AMO (Atlantic multi-decadal oscillation) and ENSO (El Niño southern oscillation) under cool and warm cycles (phases) influencing precipitation patterns in Florida are assessed in this study. Temporal shift in the occurrences of precipitation extremes and changes in the magnitudes of these extremes are evaluated in different phases. Extreme precipitation events for nine different durations are also evaluated. Assessment of spatial variability of extreme precipitation in different rain areas (meteorologically homogeneous areas), and AMO and ENSO combined influences on precipitation is also carried out. Long-term historical precipitation data from National Climatic Data Center (NCDC) are used for the statistical analyses using parametric and non-parametric methods.

A model-based 72-hour maximum precipitation (MP) was estimated for American River Watershed (ARW) in California by means of a physically-based numerical atmospheric model (Ohara et al. 2011). First, comparing the simulated basin-averaged precipitation against the PRISM data, a regional atmospheric model, MM5, was calibrated. Second, using the calibrated regional atmospheric model, the model-simulated precipitation field in ARW was successfully validated at nine individual rain gauge stations in the watershed. Then, the 1997 storm event, one of the severest storm events over ARW, was maximized by the modification of the model boundary and initial conditions. The initial and boundary conditions in the outer domain of the atmospheric model were modified by three methods: 1) the atmospheric moisture, 2) the storm event duration with maintaining equilibrium atmospheric condition, and 3) spatially shifting the atmospheric conditions. It was found that these modifications of the model boundary conditions significantly increased the precipitation over ARW. These results clearly indicate the importance of wind and moisture conditions at the boundary of the atmospheric modeling domain. The artificially maximized storm yielded 549 mm of 72-hour precipitation depth by the combination of the humidity and storm duration maximization, and 541 mm depth by shifting the atmospheric conditions to the ones toward south by 5.0 degrees. Consequently, the 72-hour maximum precipitation of the 1997 event over ARW can be maximized to as high as 550 mm. Although this study presents only a demonstrative maximization work, it shows that the presented modeling approach can be a potential alternative to the standard Probable Maximum Precipitation (PMP) estimation without depending upon the linear relationships required in the standard PMP method.

Urmia Lake is a large hyper-saline lake located in the northwest of Iran. It plays an important role in the hydrology, climate and ecology of its surrounding regions. In recent years, the water level of Urmia Lake has been dropped significantly. This study investigates the seasonal and annual variations of the lake area from 2000 to 2011 using remote sensing data. MODIS imageries of Normalized Differential Vegetation Index (NDVI) were used to extract the water surface area of the lake. Results reveal a significant decline in the lake area during the last past 12 years. Analysis of the seasonal images shows that maximum and minimum areas of Urmia Lake usually occur in winter and autumn, respectively. This study confirms the successful application of MODIS-NDVI products for retrieving the variation of the large lakes area with an acceptable spatial and temporal resolution.

Assessment of spatial and temporal extreme precipitation events due to climate variability and change is critical for future hydrologic design. Evaluation of these extremes in the past has been limited to evaluation of annual and partial duration series. However, climate-change sensitive hydrologic design requires evaluation of precipitation extremes at different temporal levels using a variety of indices. This study evaluates the variability of precipitation extremes in two climatic regions in the U. S. using WMO (World Meteorological Organization) proposed and adopted eleven indices. These indices relate to precipitation extremes at a daily temporal scale and encompass a variety of conditions including user-defined precipitation thresholds. Quantitative evaluation, statistical analyses and spatial variability of indices in a region as well across different climate zones indicate that infilling of precipitation data and existence of in homogeneities influences the assessment of trends in extreme events using indices. This paper presents preliminary results of an ongoing study.

Steppe grassland is one of the most precious green-vegetation renewable resources in Inner Mongolia of northern China as well as all over the world. Not only the grassland is the material basis for animal husbandry but it also plays an important role in sustaining vulnerable steppe ecosystem. However, one noticeable problem is that large areas of steppe (particularly typical) grassland are being degraded as a result of inappropriate anthropogenic activities (e.g., overexploitation and overgrazing) and climate change, which in turn has become a key constraint to the sustainability of grassland agriculture. For instance, 90% of the steppe grassland in China has exhibited somewhat degree of degradation. Previous studies indicated that climate in the Inner Mongolia steppe region has been displaying a warming trend, accompanied by a clear increase in air temperature during winter and serious drought in spring. Also, previous studies indicated that a grazing intensity of GI_j = 1.2 or greater would cause sustainability problems for steppe grassland. Herein, grazing intensity is defined as the ratio of the aboveground alive dry biomass per unit ungrazed area to that per unit grazed area provided that these two areas are similar in terms of hydrologic conditions and soil properties. However, while hydrology alteration and its subsequent soil erosion are two direct factors of inducing grassland degradation, few studies examined how these two factors respond to anthropogenic activities and climate change. Further, it is unclear how erosion of the top 10 to 20 cm calcic castanozem soil affects and is affected by degradation of grasses. The objectives of this study were to: 1) propose a conceptual ecohydrologic model; and 2) use the model to examine interrelations among hydrology alteration, soil erosion, and grassland degradation in a typical steppe watershed located in northeastern China. The results indicated that for the study watershed, the maximum interaction between wind and water erosion would occur at a soil moisture level of 20 to 30%. For a given vegetation coverage, soil erosion was predicted to increase by 1.7 cm yr^-1 per 1% decrease of soil moisture. The increase of soil erosion rate per 1% decrease of vegetation coverage would be larger for a lower soil moisture level than that for a higher moisture level and can be as high as 0.5 cm yr^-1. Because climate change will result in lowered soil moisture and inappropriate anthropogenic activities could drastically reduce vegetation coverage, it is expected that soil erosion would be elevated if no measure is taken. The possible measures may include grazing rotation and water table management.

In this study, GCM-based MM5 historical climate simulations for the late twentieth century (ECHAM5: 1950-1999, CCSM3: 1900-1999) were first carried out in order to validate the MM5 atmospheric model. Then, GCMs-based MM5 future climate simulations results for the 9-realization (ECAHM5: A1B1, A1B2, A1B3, A2-1, A2-2, A2-3, B1-1, B1-2, and B1-3) and for the 4-realization (CCSM3: A1B, B1, A2, and A1FI) are evaluated for the future climate change assessment on air temperature and solar radiation over Northern California. The future projections of precipitation based on the ECHAM5 and CCSM3 emission scenarios show that the future projections of air temperature from GCM-based emission scenarios have a clear trend in warming with the passage of time over Northern California, especially at the central valley area. The future projections of solar radiation do not show much of trend and the magnitude of changing solar radiation at the end of the 21st century is less than 5 W/m2 over Northern California.

In this study, the assessment of future climate change impact on precipitation were carried by means of MM5 regional atmospheric model under two GCM scenarios (ECAHM5: A1B1, A1B2, A1B3, A2-1, A2-2, A2-3, B1-1, B1-2, B1-3 and CCSM3: A1B, B1, A2, A1FI). The future projections of precipitation based on the ECHAM5 and CCSM3 emission scenarios show that the magnitude of precipitation is significantly dryer or wetter at some months at both mid-century and end of the century for the three watersheds (Sacramento River, Shasta dam, and Trinity dam), especially during wet season (DJF: December, January, and February). The annual precipitation of future projections is slightly lower than the historical annual precipitation, but the annual precipitation by individual scenarios shows the climate change vulnerability on water resources and floods for watersheds in Northern California.

Sea level rise is one of the important impacts of climate change. Accordingly, the projection of future sea-level has drawn a lot of attentions. The consensus is that the models based on physical processes may not yet predict sea-level changes with confidence. An alternative way to model global sea level rise is the empirical or semi-empirical approaches recommended in the literature. In this study, we extended the empirical model concept to incorporate spatial resolution to characterize spatial variations of sea-level rise and to investigate interactions among sea-level and sea surface temperature (SST) in different regions of the world's oceans. In our model, the world's oceans are divided into 4 regions, and both rate of sea level rise and rate of temperature change for each region are proposed to be linearly correlated with sea-level and sea surface temperature of the 4 regions. This empirical model is calibrated using published spatial sea-level data and sea surface temperature records from 1950 to 2001, and the model fit matches historical records well. Based on the calibrated parameters, both sea level and temperature of Gulf of Mexico have relatively different characteristics from those of the other 3 regions. The calibrated model indicated that sea-levels of the four regions all rise significantly in the 21st century but not at the same level. The proposed model is an alternative to existing studies in the literature.

The historical atmospheric data (precipitation, air temperature and solar radiation) were reconstructed at hourly interval with 3-km resolution from NCAR/NCEP Reanalysis data by dynamical downscaling (MM5) over Northern California and the performance for reconstructed data were validated by ground observations and by spatial data from PRISM. The validation results yielded very satisfactory results in the case of MM5 simulations from the downscaling of NCAR/NCEP reanalysis data. From this study, it is found that the reconstructed atmospheric data by MM5 atmospheric model can provide the necessary data for hydrologic or environmental models to be used in the watersheds with limited or insufficient ground observations. Furthermore, the results of this study imply that dynamical downscaling of the Global Climate Model (GCM) future climate projections for the simulation of future conditions by means of the MM5 atmospheric model can be a useful tool for the future climate change assessment.

Twenty-four years (1984-2007) of spatial-temporal water quality data from three different sampling points at the surface were evaluated in Deer Creek Reservoir in Utah. The chosen sampling locations represent the lotic, transitional and lentic zones of a typical man-made lake. The time frame included data collected before and after the completion of the Jordanelle Reservoir (1987-1992), upstream of Deer Creek. On average chlorophyll-a and phosphorus levels have dropped since 1984 and dissolved oxygen levels have remained the same. We used stepwise variable selection and multivariable regression to fit chlorophyll-a on climatological, hydrological, and water quality parameters. Analyses of variance (ANOVA) were used to quantify spatial and temporal variation. Significant spatial variation in chlorophyll-a concentration was found to be 92% higher on average in the lotic zone than the lentic zone. The regression model was also used to evaluate future water quality effects produced by different climatic change scenarios. Chlorophyll-a concentrations were used as water quality indicators to assess the in-reservoir effects of climate variation produced by meteorological changes. The model predicted an inverse relationship between air temperature and chlorophyll-a concentrations. Our findings were validated with results obtained from a computational water quality model that found that the statistical model showed similar trends of chlorophyll-a.

The spatial variability of rainfall is a significant source of error when estimating runoff as part of any rainfall based flood design method. While there are numerous stochastic rainfall models that simulate point rainfall, there is still some way to go with reliable simulation of spatial variability. To highlight this point, the spatial properties of a clustered point process model are investigated. The model is compared to an existing daily coarse-scale (0.05° ~5km) grid covering the region of Sydney and significant differences between the two are shown. The proposed remedy for these limitations is to separate the stochastic model's role of reproducing multisite statistics from the role of spatial infilling. This observation will enable a more flexible approach to generating accurate spatial rainfall distributions that match empirical data.

Many recent studies predict changes in annual precipitation patterns and impacts on water supplies based on global climate modeling. This research is less valuable for forecasting changes in severe storms, which is of primary interest for urban infrastructure studies, such as flood control and water quality planning. Examination of extreme rainfall trends over the last century can be an indicator of likely future patterns, and can illuminate deficiencies in available frequency statistics that are usually based on assumed stationarity in the historic data. This study analyzes daily data from 1893 to 2010 for the 1,100-station U.S. Historical Climatology Network (USHCN). Stations were grouped according to nine climate regions for the contiguous US. Each USHCN station dataset was analyzed to identify 1-year and 5-year rainfall at 1-day and 7-day durations. The methodology follows the analysis presented by Kunkel et al. (1998) in an analysis of 1931-1996 data. Each station dataset was considered stationary for establishment of comparative precipitation thresholds. Each partial duration series of maxima was fitted to the generalized extreme value function using CDM Smith's NetSTORM rainfall analysis software to identify station-specific rainfall maxima. In the five eastern-US climatic regions (Northeast, Southeast, East North Central, Central, and South), the annual incidence of 5-year 1-day rainfall in the 40 years since 1970 averages 26 percent higher than in the preceding 77 years. The annual incidence of 5-year 1-day rainfall in the 20 years since 1990 is 38 percent higher than in the preceding 97 years. In the Northwest, Southwest, and West, the annual incidence of 5-year 1-day rainfall is nearly identical for the pre- and post-1970 periods. Comparable trends are apparent even for 1-year 1-day rainfall: the four decades since 1970 have 19 percent more events per year than the preceding eight decades across the Northeast, South, Central, and East North Central regions. Since 1990, there have been 23 percent more 1-year 1-day rainfall events per year than during the previous century in those same regions. Analysis of 7-day rainfall yielded results similar to the 1-day findings in most climate regions. The increases correlate with shifts in annual precipitation - the eastern stations recorded seven percent more precipitation in the four decades since 1970 compared with the prior eight decades, while western stations recorded four percent more precipitation than previously over those same periods. The changes in large storm frequency are greatest in the northeastern quarter of the country; the incidence of 5-year, 1-day events since 1990 compared with the preceding nine decades increased by 51, 39, and 44 percent for the Northeast, Central, and East North Central climatic regions. While these changes may in part be driven by random variation, interdecadal patterns, and artifacts of the monitoring methodologies, they also indicate larger climatic trends, and demonstrate that the assumption of stationarity in existing extreme rainfall atlases is inappropriate in many places.

Most operational decisions for water resources infrastructure are dependent on both the timing and magnitude of flows, and therefore climate change impact assessment must consider both these characteristics. This paper examines trends in the magnitude and timings of streamflow at several stations in Satluj River basin in India. The intention is to increase the reliability of water resources systems in the basin through consideration of the observed trends. The Mann-Kendall nonparametric trend test, incorporating a correction for serial correlation and presence of ties, was used for the detection of trends. Trends in seasonal proportions of annual flow as well as actual flows have been investigated. Timings of extreme flows at several locations in the basin have also been investigated. The results reveal more trends than would be expected to occur by chance for several of the magnitude and timing measures considered in this study. The contribution of glacier melt to annual runoff at Bhakra, the major reservoir in the basin, is approximately 59% and therefore any changes in magnitude and timings of water availability at the reservoir could have significant implications for its operation. Further, climate change induced changes in the timings and magnitude of water availability at Bhakra, the major reservoir in the basin, could put the drinking water supplies of millions of people at risk. The study will contribute towards climate change modeling efforts being undertaken in a climatologically sensitive basin such as Satluj.

In this study, recent precipitation trends based on CCSM3-based MM5 simulations were investigated against PRISM-based precipitation for 11 years from water year 2000 to water year 2010 for 8 watersheds in Northern California. Six precipitation projections (A1B1, A2, B1, A1FI, Ensemble1 and Ensemble2) were used for this study. In general, the case of Ensemble2 shows the most realistic trends against PRISM precipitation, especially for last 5 years, and is similar to PRISM in total volume of precipitation for 11 years. However, the case of A1FI also shows the realistic trends in mountainous watersheds (UFRW, ARW and YBW). It means that the precipitation under A1FI scenario is also important for future climate change impact study. Less precipitation was found under A1B and A1FI scenarios and more precipitation was found under A2 scenario. Although precipitation under B1 scenario is realistic compared to other scenarios (A1B, A2 and A1FI), the most realistic scenario is Ensemble2 (ensemble average of 4 scenarios). However, it was found that the precipitation difference against PRISM precipitation is locally different for all scenarios. Through the analyses for the extreme precipitation between the control run for 20th century and the projections for 21st century under CCSM3 gas emission scenarios, the extreme precipitation not only under A1B, A2 and B1 but also under A1FI scenario was much frequently found than historical period. It means that the A1FI scenario is also important to assess the future climate change impacts not only for water resources but also extreme floods.

Fine grid resolution and temporal scales are crucial to analyze the hydrologic impacts from extreme floods for a watershed. A regional scale atmospheric model such as MM5 is useful to achieve this purpose because ground observation stations are rarely located within watersheds. However, the achieved data set by a model should be validated against observation data before it is used. In this study, historical global reanalysis atmospheric data (NCAR/NCEP) was dynamically downscaled to a 3km resolution over the Upper Feather, Yuba, and American River watersheds using the Fifth-Generation NCAR / Penn State Mesoscale Model (MM5). To validate the reconstructed precipitation, historical data from California Data Exchange Center (CDEC) stations were first used. However, the data that can be obtained from them is coarse throughout the watersheds so historical data from PRISM (parameter-elevation regressions on independent slopes model) were also used. The hourly increment precipitation data found at the CDEC stations in each watershed are used to verify the temporal accuracy of the model simulation, and the PRISM simulations are used to verify the monthly basin-average precipitation and its spatial distribution over each watershed.

It has been reported that 1995-2006 are the warmest years in the history of instrumentation (since 1850) and the global surface temperature rise is attributed to the green house gases effect. The combined global land and ocean surface temperature for July 2010 was the second warmest on record, behind 1998, and the warmest average January-July on record. The effects of global warming will bring changes in annual average precipitation values in the order of ±20%. The southern African region has been projected to receive less precipitation and Swaziland is no exception. The average results (precipitation, potential evapotranspiration) of 12 general circulation models (GCMs) in the future (2021 to 2060) and the observed stream flows were input to a calibrated rainfall runoff model (Watbal model) in order to determine the water resources in four catchments in Swaziland under expected climate change. Simulation results show that, the present streamflow lie within the 95% confidence interval of the projected flows in all the catchments. This implies that there is no significance difference between the observed and projected stream flow at 5% confidence level. However, the runoff change between the 2.5% and 97.5% quantile ranges from -17.4 to 26.6; -31.2 to 18.1; -40.3 to 27.7; and -40.8 to 34.9% in the Komati, Mbuluzi, Usutu and Ngwavuma catchments respectively and the median of the runoff change is negative for most of the months in three catchments (Usutu, Mbuluzi and Ngwavuma) except for the Komati catchment. Thus, there will be less runoff in the three catchments under expected climate change. Therefore, proposed adaptation options to climate change for Swaziland are: efficient water use (at domestic and farm level), wastewater recycling, rainwater harvesting, ground water utilization, implementation of integrated water resources management (IWRM), water resources development and inter-basin transfers.

The issue of climate change is a major potential impediment to effective long-range policies and management of water resources. Recently the National Aeronautics and Space Administration published a report revealing clear evidence that global climate change is occurring as this is written. This undeniable evidence of climate change must be a significant facor in water manageent since it challenges adds significant uncertainty to the reliability of past hydrologic records. This risk of uncertainty is especially disturbing for effective water sharing across jurisdictional bundaries. This article summarizes the risks to existing transboundary water sharing agreements imposed by climate change as well as identifies those agreements most at risk.

Dramatic population growth in urban areas with limited water resources with adequate quality and quantity especially in arid and semi-arid areas have resulted in increasing tensions in a reliable water supply. Growth and change of a comprehensive water supply system makes the complex relationship among system's components more sensitive to the operating policies. All changing factors and variables should be considered in system operation in order to provide an understanding of system performance over time to provide reliable urban water supply schemes toward its improvement. In this study, systems dynamic modeling approach is used to simulate the system behavior through time at an integrated fashion. The simplified water supply system of Tehran metropolitan area, the capital of Iran, has been considered as the case study of this paper. The considered water supply system consists of several components which are connected with complicated interactions to satisfy water demands such as drinking water, agricultural farming and industrial requirements as well as many other possible needs. Reliability of this system is evaluated. The results of the developed model can be used as an indicator of the system's state to decide about the implementation of system rehabilitation and reconstruction projects.

World Water Forums have been held five times, beginning with the 1st World Water Forum in 1997in Marrakech, Morocco. At the 5th World Water Forum in 2009 in Istanbul, Turkey, considerable attention was paid to the Water and Energy nexus. One session entitled Taming Bigfooot: Reducing Water and Energy Footprint explored the innovative technologies that can minimize water consumers energy needs and power producers water needs. Panelists explored gaps in technology in areas such as irrigation and wastewater treatment and which new technologies might hold promise to improve efficiency on both sides of the nexus. The theme for the 6th World Water Forum in 2012 in Marseilles, France is "Time for Solutions". The Forum will encompass three overall strategic directions: ≤ Ensure everyone's well-being; ≤ Contribute to economic development; and ≤ Keep the planet blue. Under these strategic directions are "12 Priorities for Action" which are summarized on the Forum website at http://www.worldwaterforum6.org/enicommissions/thematic/. Priority for Action 2.3 is designated "Harmonize water and energy" and is being coordinated by the International Water Association and International Hydropower Association. The American Water Resources Association (AWRA) and ASCE' s Environmental and Water Resources Institute are collaborating on efforts to explore progress on harmonization in the United States and throughout North America. This paper will report on preparations at the regional level and results to be presented at the 6th World Water Forum.

The Panama Canal provides one of the most important navigation routes and port hubs in the world. It consists of a 77-kilometer (48 mile) ship channel that joins the Pacific and Atlantic Oceans. It has been one of the most difficult engineering projects ever undertaken and has replaced the alternative long and dangerous routes through the Strait of Magellan or Cape Horn at the southernmost tip of South America. The Canal not only services transport activities between eastern and western North America, but also South America, Asia and Europe. Work on the Canal started in 1904, finished in 1913, and was open for traffic on August 15, 1914. In total, close to a million vessels have passed through it to date. It has been named one of the seven modern wonders of the world by the American Society of Civil Engineers. The maximum size of vessel that can use the canal as it stands now, typically has a Dead Weight Tonnage of 65,000-80,000 tons and is known as Panamax. However, today's technology is pushing towards even bigger ships that largely exceed the current maximum capacity and size limits. These vessels are known as Post-Panamax. The Canal has had no other choice but to "reinvent" itself in order to keep up with these new floating high capacity ships, and is doing so essentially by expanding the canal (and related infrastructure) to meet the new demand. The Government of Panama is investing approximately US$ 6 Billion to improve infrastructure in order to accommodate the passage of those vessels. The Canal expansion is currently under way and it is to be finished in 2014 (coinciding with the Canal's 100th anniversary). It consists of a new set of locks on the Pacific and the Atlantic that will allow the larger ships to maneuver much more easily than the existing infrastructure. Each lock will have three chambers that act as reutilization containers. The program also entails the widening and deepening of existing navigational channels, elevation of the Gatun Lake and the deepening of the Culebra (or Gaillard) Cut (the narrowest section in the entire Canal). The project entails massive excavation, filling and related civil works plus the installation of hydraulic and sophisticated electro-mechanical equipment. The new sets of locks are hydraulically driven and have been designed under two main principles: (i) the system should be environmentally sound while using the most efficient water saving technologies, and (ii) it should make the best use of the Canal watershed water supply to avoid building new reservoirs. The Panama Canal Authority (ACP for its acronym in Spanish) has deployed a massive effort to make this project as sustainable and water efficient as possible. Construction contractors are under strict supervision, and the project is moving forward achieving the planned goals as well as sustainability objectives pertaining to construction and operation.

In the United States, monitoring evapotranspiration (ET) is primarily focused in agricultural and wildland environments. With educational advancements stressing water conservation in urban areas, there is a newfound desire to apply ET data as part of wastewater reuse options for supplemental irrigation, and for more accurate modeling of rain garden and green roof controls for stormwater management. Unfortunately, most publicly available data located near urban areas is found to be substantially different from a well-watered landscape surface and required conversion for use. Likewise, adjustment factors for different landscape surfaces are, in most cases, developed for agricultural situations and their use in highly disturbed urban environments has not been well documented. One of the products of this research examined these available ET values and then mapped them for major urban areas. The product of mapping these locations will be used in conjunction with associated rainfall information to calculate irrigation requirements in urban areas as part of a Water Environment Research Foundation (WERF)-sponsored project on the beneficial uses of stormwater.

New laboratory experiments were conducted on a radial gate to evaluate the energymomentum procedure for calibration. Prior work had used an artificial energy correction, E_corr, to match observed conditions. In the current work, non-hydrostatic pressures, velocity, and momentum distribution coefficients were used instead. This avoids the quirky behavior associated with E_corr. Non-hydrostatic pressure distributions were found in the jet, but they had an insignificant influence on the head-discharge calibration. Velocity-distribution coefficients were added to both the energy and momentum equations. The value of the momentum coefficient was related to the relative submergence; roughly 1.08 for low submergence, increasing to 1.3 at high submergence. For this data set, the energy equation was able to predict free-flow discharge within ± 2%. The energy-momentum equations were able to predict the discharge for submerged flow to ± 5% when the downstream channel width was equal to the gate chamber width, and within ±8% for a wider downstream channel. No improvement was found for estimating the wall force exerted downstream when the tailwater channel is wider than the gate. These new calibrations have been implemented in the new WinGate software.

Bottom sluice gates are widely used to measure flow in water distribution systems. Energy-momentum balance is a good way to establish accurate gate equations, because it accounts for the downstream pool configuration. However, corrections are needed to address particular flow regimes, such as the transition from free flow to submerged flow, and to account for real fluid effects such as head losses. Most methods only consider corrections on energy and momentum. However, the contraction coefficient C_c may be need to be adjusted too. Ususally, the same C_c is assumed under submerged flow as in free flow (around 0.6), even with a very large gate opening. Yet, when a gate is completely pulled out of the water, there is no contraction (C_c=1), and by continuity, C_c should be larger than 0.6 at large opening and submergence. This is a frequent situation in an irrigation canal. Values for C_c can be derived from energy and momentum balance applied between the upstream and downstream sections of the gate, with the pressure force on the gate obtained from potential flow theory. The resulting C_c vary with gate opening, and ensure a smooth transition between the different regimes (free flow, partially submerged, fully submerged, fully open). Gate hydraulic relationships were studied in the laboratory with 3D ADV measurements, with special attention to velocity distributions upstream of the gate and in the submerged jet for various gate openings. The experimental configurations were simulated with Reynolds-Averaged Navier Stokes equations using RNG-k-ε model for turbulence simulation. Both numerical and experimental approaches confirm the variation of C_c with gate opening. They provide values of corrections that should be applied to the energy and momentum balance (Coriolis and Boussinesq coefficients, head loss and friction forces) so that to improve the calculation of contraction and discharge coefficients.

WinSRFR is a software package for the hydraulic analysis of surface irrigation systems. The software can be used to conduct simulations, carry out design and operational analyses, and evaluate performance from field-measured data. Version 3.1 was released in 2009 and a new version, V. 4.1 is scheduled for 2012. This release provides a limited number of analytical enhancements for the end user, but it represents a major software upgrade. The simulation engine, known as SRFR, has been entirely rewritten using modern object-oriented programming concepts. This recoding effort was undertaken to facilitate the continued development of the SRFR code and to provide the application with a well-defined application programming interface. The paper discusses the architecture of the new SRFR engine and the resulting enhancements to the WinSRFR program.

Chemical products, mainly chlorine, are often used to control or eradicate the Zebra Mussel, Dreissena Polymorpha, in pressurised irrigation pipes, although other disinfectants have been used, such as hydrogen peroxide. An optimum application of these substances is essential to achieve maximum effectiveness at minimum cost, without harmful effects on crops or the environment. This work defines tools and techniques for satisfactory process design, taking into account the specifics of operation and flow structure in irrigation system networks (very different from those of domestic water supply), the species to be combated and the high concentration of organic material in irrigation water. New specific functions have been implemented and applied in GESTAR 2010 (www.gestarcad.com), the software application for designing and managing pressurised irrigation networks, facilitating the use of the urban network water quality simulation module from the EPANET2 programme, adapting it for these purposes and obtaining predictions for the evolution of the concentration of the additive used over time at all points in the network, considering the reaction in the raw untreated water supply and the reaction with the wall, due to the effect of interaction with the invasive mollusc species (not necessarily zebra mussel).

A research project was carried out to estimate daily crop water stress index (CWSI) of corn, planted in NE Colorado under limited irrigation practice. In CWSI estimation, required weather/canopy parameters were measured every day between 1200 and 1300 hours, while the upper and lower limits of air-canopy temperature differential (dT) were identified by applying several previously-developed methods. A simple approach for checking the accuracy of implemented dT limits was proposed. In addition, corn actual evapotranspiration (ET) was estimated by combining resulted CWSI values with corn potential ET, calculated using the data collected at a nearby weather station. Despite a significant variation among them, all of the implemented methods for identifying upper and lower dT limits resulted in a corn ET lower than its potential rate, indicating that CWSI approach can effectively detect the existence of water stress in corn. The differences among applied methods could be attributed to the differences in agro-climatic conditions under which they were developed.

The Angostura Irrigation District (AID), located in western South Dakota, delivers water to approximately 12,000 acres of mainly corn and alfalfa fields within AID boundaries. Sediment-laden waste from the delivery system and fields enters directly into the Cheyenne River, which is listed by the South Dakota Department of Environment and Natural Resources (SD DENR) as impaired for total suspended solids (TSS). As with many smaller irrigation districts, the process of ordering, delivering, and accounting for water as well as estimating daily reservoir releases within the AID was completed manually using paper hardcopies. This process proved time-consuming (typically 1.5 hours per day) for AID staff and led to errors in delivery amounts which in turn, can increase the amount of sediment-laden flows that enter the Cheyenne River. To help remediate this issue, a Geographic Information System (GIS) will be incorporated to determine irrigated acreage, to determine total amount of water applied, and to present graphical aggregate reports on current water orders and percentage of individual water allotments used. In the water order and delivery process, accuracy and timeliness is increased by replacing the hardcopy water order and measurement sheets used by the field crew with Global Positioning System-(GPS-) enabled, hand-held, smart mobile devices. The easy-to-use, custom-built electronic forms on the device, which mimic the paper hardcopies used in the past, help to ensure the accuracy of data input, while automated synchronization with the master database allows rapid and accurate uploading of all data collected in the field. Transparency, efficiency, and forecasting capabilities are increased by using enterprise-level, browser-based tools allowing irrigation managers to view aggregate reports of water usage and browser-based tools also allow managers to generate custom reports by gate, field, and date range.

The irrigation industry is experiencing a growth in the use of magnetic meters for measuring the flow rate and volume in irrigation pipelines. Historically, propeller meters have been the device selected by users. New legislation in California (SB7x7) will require measurement devices at key locations for irrigation water delivery. Some users are very interested in the magnetic meter for making the measurement at the turnout or farm gate. The key feature of the new meter is the ability for the device to work in less than ideal flow conditions. Electromagnetic meters have been tested by the Irrigation Training and Research Center in lab and field pipelines located less than the 10 diameters upstream of disturbances with good results. There are several manufacturers that are selling units to the irrigation market as well as several types of magnetic meter designs. This paper discusses how a magnetic flow meter works, advantages/disadvantages of this type of meter, test results, and new guidelines for field applications.

Algae may cause various disturbances in irrigation canals, such as conveyance decrease, clogging and water quality depreciation. Strategies of regular flushes were designed for two open-channels in southern France. The objective of flushes is to maintain the algal biomass by increasing the shear stress in the canal, thanks to hydraulic control. During a flush, turbidity is increased, possibly causing problems for end-users or treatment plants. While automation largely improved the hydraulic performance of canals, considering water quality control is a new challenge for canal control. In this paper, open-loop and closed-loop control strategies of turbidity are described. These strategies rely on transfer functions established between discharge (command input) and turbidity (output) at different locations of the canal. Simulation models allow testing easily various control methods. Flushes were also implemented in the Canal de Provence routinely in 2011. The analysis of the field data allows improving the discharge-turbidity transfer functions. Then, real-time closed-loop control was also implemented. These tests bring a new insight to sensor positioning and canal control, applied here to non-hydraulic variables.

The velocity distribution in open-channels is still the core of many investigations. In particular, vegetation influence is being widely studied as it largely affects the flow properties, and it must be taken into accounts in many practical applications such as discharge estimation, flow level prediction, pollutant dispersion, sediment deposition dynamics... Most of these investigation are conducted in laboratory flumes where accurate experimental techniques can be used, such as micro-ADV and PIV. They lead to a better understanding of turbulence-induced forces by vegetation, effect of plant strength and foliage, Monami waves... In natural stream, the effect of vegetation has mainly focused on the influence of vegetation on resistance (Green et al., 2006). Artificial water conveyance systems may be considered as intermediate between laboratory flumes and natural streams since they have generally a regular shape (such as laboratory flumes) but also present a part of the complexity of natural stream, with the presence of natural and non-uniform vegetation. This vegetation may be composed of macrophytes, but smaller-size colonies present in open-channels may also affect velocity profiles, as observed in laboratory flumes (Labiod et al., 2007; Graba et al., 2010). Field observations showed that the development of such vegetation induced very large variations of roughness coefficients within short periods (a few weeks), causing serious management problems (Lozano et al., 2012) and large deviations of rating curves. Measurement techniques based on velocity probes and standard velocity distributions may also be affected by these deviations. The main focus of this paper is the evolution of velocity profiles in real-scale artificial open-channels faced with vegetation growth. The objective is to link the parameters of the velocity distribution function with observed physical characteristics: channel characteristics, vegetation height. We would like to show that the laboratory knowledge on submerged vegetation can help to analyze velocity profiles and to compute discharge for real channel with some simplifications. The analysis is based on field measurements in an irrigation canal performed by micro-ADV during 8 months and on the knowledge from laboratory flow above vegetation. The validity of the modified log-wake law (Guo and Julien, 2008) derived from laboratory flume experiments is studied then. The effect of vegetation growth on roughness, and then velocity distribution, is finally discussed.

Accurate daily reference evapotranspiration (ET) values are needed to estimate crop water demand for irrigation management and hydrologic modeling purposes. The Bushland Reference ET Calculator was developed by the USDA-ARS Conservation and Production Research Laboratory at Bushland, Texas for calculating hourly and daily grass and alfalfa reference ET. The user-friendly interface for the calculator was developed using .NET programming. The calculator uses the ASCE Standardized Reference Evapotranspiration (ET) Equation for calculating both grass and alfalfa reference ET at hourly and daily time steps. Users have the option of using a single set or time series weather data to calculate reference ET. Daily reference ET can be calculated either by summing the hourly ET values for a given day or by using daily averages of the climatic data. Although the Bushland Reference ET Calculator was designed and developed for use mainly by producers and crop consultants to manage irrigation scheduling, it can also be used in educational training, research, and other practical applications. This paper demonstrates use of the Bushland Reference ET Calculator that is available from the USDA-ARS Conservation and Production Research Laboratory web site to interested users at no cost.

WinGate is a new interactive computer program that provides discharge calibration of canal check structures containing radial gates and/or vertical slide gates. The software provides a graphical user interface to define dimensions and hydraulic properties of the canal, check structure, and gates, and enables the user to compute discharge for specific gate settings or the gate openings needed to pass a specified discharge. The software utilizes the latest energy-momentum calibration equations that enable calibration for a wide range of upstream and downstream cross sections. Rating tables covering ranges of canal water level conditions can be generated for both free flow and submerged flow cases.

Systems thinking can facilitate holistic understanding of complex system behavior. When applied to environmental systems impacted by human activities, systems thinking can provide insights for developing effective plans to protect ecosystem integrity and support socioeconomic development. In this study, the main system dynamics archetype governing a lake's eutrophication problem is described to explain the system's problematic behavior and identify policies for mitigation. Furthermore, in order to put systems thinking concepts into practice, an integrated system dynamics model is developed to simulate the interaction between key socio-economic subsystems and natural processes driving eutrophication. The model is applied to holistically characterize the lake's recovery from its hypereutrophic state and assess a number of proposed TMDL reduction policies, including phosphorous load reductions from point sources and non-point sources.

Urban water infrastructure systems, including drinking water, wastewater, and stormwater, should be designed to efficiently use water and energy resources. Current design paradigms typically neglect the interconnection among these systems; water, wastewater, and stormwater are treated at centralized facilities, and water services are distributed within a municipality through pipe networks. Due to water shortages and limited budgets, water utilities may encourage individual households to adopt water reuse, water conservation, and lot-level stormwater treatment technologies, which may produce a decentralized water service system. Transitioning from a centralized to a decentralized approach within urban water infrastructure systems will change demands and affect the performance of the existing infrastructure and the use of energy and water resources. To enable exploration of the impacts of decentralization on the sustainability and resilience of urban water infrastructure systems, a Complex Adaptive Systems (CAS) approach is developed here. This modeling framework characterizes the various feedback loops, dynamic interactions, and emergent phenomena that result from the interactions of decentralized and centralized components of the water infrastructure systems. Specifically, rainwater harvesting is explored as a decentralization technology, which reduces stormwater service demands and drinking water demands on the centralized infrastructure systems. An agent-based modeling approach is used to simulate technology adoption of individual consumers in response to water shortages and is coupled with water and energy utilization models. The framework provides insight to the interconnections and interactions between the consumers, water supply and delivery system and the effect of these interactions on water and energy use and sustainability; infrastructure system design; and system resilience, as a system transitions from a centralized to a decentralized layout.

Modeling of the San Joaquin valley using SWAT can give a comprehensive overview of hydrologic traits of the San Joaquin River and its tributaries, specifically for nutrients like nitrate. The San Joaquin valley is a site of intense modeling interest and policy making, as the San Joaquin River joins the Sacramento River to feed into the Delta. The environmental impact of dissolved oxygen on aquatic life on the Delta is a particularly key concern (Quinn 2000). The San Joaquin watershed also represents considerable investment in agriculture on the valley floor and has been studied for nitrate, sediment, and salinity concerns particularly with regard to agricultural runoff. Evaluation of model accuracy and utility are important for any future studies on the San Joaquin River for hydrology and nutrients, especially in regards to policy making. Criteria for model evaluation are based on model accuracy and reliable conclusions on the watershed traits. The accuracy of the model is summarized by the goodness-of-fit (e.g., Nash- Sutcliffe efficiency, mean of sum of square residuals), as well as the ability of the model to reproduce trustworthy results. Reliable conclusions concerning the hydrological simulation of the San Joaquin are based on recognizable hydrology trends in surface flow and nutrient origin and transport, particularly nitrates.

Hydropower potential has remained mostly untapped for many years in the Mekong/Lancang River Basin, which drains land in China, Myanmar, Thailand, Laos, Cambodia and Vietnam. Currently the basin is undergoing extensive hydropower development that will likely result in altering its natural flow and sediment regimes. This in turn could significantly disrupt as many as 32 delicate and productive ecosystems throughout the region. Within the Mekong basin, the Se San, Sre Pok and Se Kong sub-basins (collectively called the "3S" basin) are a particularly important set of adjacent, transboundary watersheds with respect to biodiversity and ecological productivity, and serve as an important source of flow and sediment to the lower mainstream Mekong River. Currently, 19 hydropower projects are in operation or are under construction in the 3S basin, but this number could reach 41 by 2020 (with an installed capacity of just over 6,300 MW). Studies on potential impacts of reservoirs in the 3S basin are limited, and extensive research is still required to better understand the potential disruption of the sediment regime, which will impact (1) hydropower output and reliability; (2) the geomorphologic makeup of the system, and (3) the health and productivity of the region's exceptionally biodiverse ecosystems. The work to be presented includes the development of a sediment accounting tool for the Mekong basin applied to the 3S basin. This tool is a daily time-step mass-balance simulation model of flow and sediment to predict in relative terms the spatial and temporal accumulation and depletion of sediment in tributary reaches and in reservoirs under different operating policies. Discussion will include use of the model to identify reservoirs that could significantly alter the natural sediment regime, and for which improved sediment and flow management practices could have a positive impact. Relative tradeoffs between hydropower production and sediment regime alteration will be discussed for different operating policies.

The growing water demand and limited water supply have caused water resources bankruptcy, resulting in failure of many water resources systems around the world to meet the imposed demands by the users. Water resources bankruptcy is associated with conflicts among the beneficiaries whose demands/claims exceed the total available water. Therefore, developing fair allocation rules that minimize tensions between the beneficiaries of water resource systems is essential to establish sustainable water resource governance systems. This study suggests application of bankruptcy rules to develop fair water allocation schemes. To underline the utility of bankruptcy rules in resolving water resources conflicts a range of bankruptcy rules, namely the Proportional (P), Adjusted Proportional (AP), Constrained Equal Award (CEA), Constrained Equal Loss (CEL), Talmud (Tal) and Piniles (Pin) rules, are reviewed and applied to a hypothetical groundwater bankruptcy problem. In this problem the total water demand of three farmers, based on their water rights, exceeds the safe yield of the aquifer. The differences between the obtained results based on the different bankruptcy rules are discussed and the most acceptable rules for the example case are recognized based on the Plurality rule.

This paper summarizes methodological advances in regional log-space skewness analyses that support flood-frequency analysis with the log Pearson Type III (LP3) distribution. A Bayesian Weighted Least Squares/Generalized Least Squares (B-WLS/B-GLS) methodology that relates observed skewness coefficient estimators to basin characteristics in conjunction with diagnostic statistics represents an extension of the previously developed B-GLS methodology. B-WLS/B-GLS has been shown to be effective in two California studies. B-WLS/B-GLS uses B-WLS to generate stable estimators of model parameters and B-GLS to estimate the precision of those B-WLS regression parameters, as well as the precision of the model. The study described here employs this methodology to develop a regional skewness model for the State of Iowa. To provide cost effective peak-flow data for smaller drainage basins in Iowa, the U.S. Geological Survey operates a large network of crest stage gages (CSGs) that only record flow values above an identified recording threshold (thus producing a censored data record). CSGs are different from continuous-record gages, which record almost all flow values and have been used in previous B-GLS and B-WLS/B-GLS regional skewness studies. The complexity of analyzing a large CSG network is addressed by using the B-WLS/B-GLS framework along with the Expected Moments Algorithm (EMA). Because EMA allows for the censoring of low outliers, as well as the use of estimated interval discharges for missing, censored, and historic data, it complicates the calculations of effective record length (and effective concurrent record length) used to describe the precision of sample estimators because the peak discharges are no longer solely represented by single values. Thus new record length calculations were developed. The regional skewness analysis for the State of Iowa illustrates the value of the new B-LS/B-GLS methodology with these new extensions.

The five littoral Caspian Sea states, namely Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan, have been in negotiations on establishing a legal regime for governing the sea for almost two decades. What makes the Caspian Sea conflict more complicated is the immense amount of valuable oil and gas resources in the sea. The previous studies of the conflict have intimately focused on finding an appropriate division rule for sharing the water as well as gas and oil resources in the seabed, ignoring the environmental utilities associated with the possible division rules. This is despite the fact that Caspian Sea is the home to the most precious sturgeons, supplying 90% of the world's caviar. Therefore, this study bridges the gap of previous ones of the Caspian Sea conflict by adding the environmental dimension to the conflict analysis. Four different cooperative game theoretic solution concepts, including Nash-Harsanyi, Shapely, Nucleolus, and τ- value are used to find the fair and efficient allocation of the Caspian Sea resources to the five states. The results are finally compared with previous ones that ignored the environmental aspect of the problem to highlight the importance of environmental benefits in the Caspian Sea negotiations.

Being one of the specially protected areas declared by Environmental Protection Agency for Special Areas in Turkey (EPASA), Göcek Bay is threatened by increasing boat tourism. Because of the insufficient legal practices and regulations, boats continue to discharge their domestic waste and bilge wastewaters to the bay. Large scale measures are being planned for decreasing the pollution and protecting the region. For a sustainable coastal management, technical, social, political and economic tools are needed to be used. For environmental investments, it is necessary that they should be identified in monetary terms to aid decision makers. In this study, data from a Choice Experiment survey done in the region is used to present the basic perception of users of Göcek towards the environmental problems and future investments and a binary logit analysis is done to show the motivations behind peoples' willingness to pay for the planned improvements.

The Stream Water Quality (SWQ) Model is a multi-constituent, semi-Lagrangian model capable of quickly and accurately simulating one-dimensional flow, volume and transport in advection-dominated streams. Semi-Lagrangian models, which have received relatively sparse attention from researchers in comparison to Eulerian models, offer (1) highly accurate treatment of advective transport, and (2) unconditional stability for any time step duration and segmenting scheme. To demonstrate the potential advantages of using SWQ in advection-dominated, variable constituent loading settings, the model was evaluated in comparison to the Environmental Protection Agency's (EPA's) popular Eulerian water quality model QUAL2K. Model comparisons were conducted for (1) steady state flow and steady state concentration and (2) steady state flow and nonsteady state concentration (a 24-hour cycle was simulated, during which time concentration was linearly varied on an hourly basis). In model comparisons, SWQ achieved stability and high accuracy with more flexibility than QUAL2K for a variety of combinations of time step duration and segmentation for constituents including Dissolved Oxygen, Biochemical Oxygen Demand, Organic and Inorganic Nitrogen and Phosphorus species, and Phytoplankton. SWQ appears to be a more stable and robust alternative to QUAL2K.

Water scarcity leads to conflict and nowhere is this statement more evident than in those cases where shared watercourses cross or form political. Unless a means of shared utilization of these waters can be created, serious economic, political, financial, and even military consequences may develop, often to the detriment of both, or all, parties involved. Although the impediments to water sharing are many and varied, certain common obstacles exist. An understanding of these obstacles is essential if some sort of mutually agreed upon water sharing is to come to pass. The various components of a formal water sharing agreement have been reviewed and analyzed by a Tasking Committee composed of water resources experts in a number of fields. the essential components are described in a new ASCE/EWR Standard publication on Water Sharing. This presentation and publication describes this recently published Standard, discussing its organization

Urban water management specifies supply-side infrastructure and demand-side policies to balance water supply and demands for social and environmental systems. As the sustainability of water resources depends on the dynamic interactions among the environmental, technological, and social characteristics of the water system and local population, an adaptive water management approach can be used to update utility decisions based on the feedback among these systems and may enable a more efficient use of resources. Adaptive demand-side management strategies, such as regulating water for outdoor use, can be designed with increasing restrictions corresponding to the depletion of reservoirs. Adaptive supply-side strategies supplement supply by increasing the volume of water that is transferred among basins when reservoirs levels drop. Frequent water use restrictions, however, can have adverse effects on property values, due to prolonged periods without lawn watering, while pumping water from external basins carries a high cost due to energy requirements. A trade-off exists between the management costs to the water utility and the number of day when outdoor water use is restricted. In this study, a Complex Adaptive Systems (CAS) framework is used to simulate the adaptive behaviors of consumers, the adaptive decisions of the water utility, and an engineering model of the water supply infrastructure. The CAS framework is coupled with a multi-objective optimization methodology to evaluate a combination of supply-side and demand-side adaptive water management strategies in achieving the conflicting goals of minimizing management costs and minimizing the number of days with outdoor water use restrictions. An evolutionary computation-based methodology, Hypervolume Maximizing Multi-objective Evolutionary Algorithm (HM2EA), is applied to an illustrative case study of an urban water supply system to explore Pareto-optimal solution sets of adaptive water management strategies.

With over 9.5 million residents in 2010 distributed across 14 major river basins, 159 counties, over 500 cities, the establishment of the first Comprehensive State-wide Water Management Plan, and its corresponding regional water planning process, in January 2008 was an ambitious undertaking for the State of Georgia. Each of the ten water planning regions has an appointed water planning council of 30 members representing a wide range of interests, including industrial, municipal, power generation, agriculture, environmental, navigation, recreation, and flood control. The Councils have been working since 2009 to develop Regional Water Plans (RWPs) which are consistent across the State while still being reflective of the diversity of water resources and stakeholders. Each council's recommended plan is scheduled to be considered for adoption by the Georgia Environmental Protection Division by September, 2011. Each RWP lays out a roadmap for implementing integrated and specific management practices designed to ensure each Region's goals and visions are met over the next 40 years. The practices target four water resource areas (water conservation, water supply, wastewater, and water quality) based on the results of a series of resource assessments (surface water, ground water and assimilative capacity). This paper provides an overview of the challenges experienced during the planning process and will highlight the lessons learned in developing an RWP. Two Councils, the Coosa-North Georgia (CNG), draining to the Gulf of Mexico and comprising most of the mountainous, northern portion of the state, and the Upper Oconee (UO), which is located in central Georgia and drains to the Atlantic Ocean will be utilized to illustrate the diverse geographic and stakeholder boundaries crossed by this effort.

As BMP systems become increasingly known as effective mechanisms for controlling stormwater runoff produced within urban environments, the need also increases for an efficient means to compare performance results from various types of BMP controls that also includes whole life cycle cost data. Facilitating the development of these numbers for comparison is essential to selecting the most appropriate BMP system for a particular site. The BMP Systems Effectiveness and Life Cycle Cost Evaluation (SELECT) Model, a Microsoft Excel based tool, provides a platform that allows multiple stormwater BMP system performances to be quantified and subsequently generates whole life cycle costs specific to each system. A case study for the Saylor Grove Wetland BMP site in the Wissahickon watershed of Philadelphia, Pennsylvania has been completed. How the SELECT model is used to represent the wetland area and the resulting water quality, quantity, and cost calculations are discussed herein.

This paper summarizes a comprehensive examination of the current and likely future of California's water resource system, as well as promising long-term directions for policy and management. Long-term challenges include declining state and federal resources, climate changes, population growth, and continued disruptions of native ecosystems. Improvements in technology and in local water management capabilities are likely to be helpful, but changes in state and federal regulatory and management institutions and policies will be needed to manage such changes and opportunities well. The work was done by a team of distinguished scholars from economics, engineering, law, biology, and geology.

Multi-criteria decision making problems are often associated with trade-offs between performances of the available alternative solutions under the considered decision making criteria. These problems become more complex when uncertainty is associated. This paper applies a Monte-Carlo multi-criteria decision making method for solving the California's Sacramento-San Joaquin Delta problem in which the best alternative for exporting water from the Delta should be selected based on two main criteria, namely the economic cost and environmental performance. To deal with the uncertainty involved, the stochastic decision making problem is converted into numerous deterministic problems through a Monte-Carlo selection. Each deterministic problem is then solved using a range of multi-criteria decision making methods. The overall winning probabilities of the alternatives under each method are calculated and compared with the results obtained in previous studies which used conflict resolution methods, namely, non-cooperative game theory, fall-back bargaining, and social choice rules to suggest optimal solutions for the Delta problem.

The study presents the successful implementation of an optimization algorithm for selecting the number, sizing, and placement of air valves (or vacuum relief valves) in refinery cooling water systems to minimize the impact of hydraulic transients. Optimal solutions are sought using a state-of-the-art Multi-Objective Genetic Algorithm (MOGA) named ε-NSGAII. The algorithm is combined with a computer program for hydraulic transient analysis. The combined code automatically evaluates combinations of an unknown number of air valves, their sizes and locations to effectively mitigate excessive water hammer pressures or loads below acceptable (design) magnitudes. Within affordable computation time, the algorithm effectively creates a set of optimal solutions with conflicting objectives. These objectives include 1) minimizing the number of air valves, 2) minimizing the systemwide maximum pressure, and 3) minimizing the systemwide maximum water hammer load. Ultimately, the multiobjective optimal design process achieves anticipated goals of reducing cost and increasing reliability of the selected engineering design.

The U.S. Geological Survey (USGS) is currently updating at-site flood frequency estimates for USGS streamflow-gaging stations in the desert region of California. The at-site flood-frequency analysis is complicated by short record lengths (less than 20 years is common) and numerous zero flows/low outliers at many sites. Estimates of the three parameters (mean, standard deviation, and skew) required for fitting the log Pearson Type 3 (LP3) distribution are likely to be highly unreliable based on the limited and heavily censored at-site data. In a generalization of the recommendations in Bulletin 17B, a regional analysis was used to develop regional estimates of all three parameters (mean, standard deviation, and skew) of the LP3 distribution. A regional skew value of zero from a previously published report was used with a new estimated mean squared error (MSE) of 0.20. A weighted least squares (WLS) regression method was used to develop both a regional standard deviation and a mean model based on annual peak-discharge data for 33 USGS stations throughout California's desert region. At-site standard deviation and mean values were determined by using an expected moments algorithm (EMA) method for fitting the LP3 distribution to the logarithms of annual peak-discharge data. Additionally, a multiple Grubbs-Beck (MGB) test, a generalization of the test recommended in Bulletin 17B, was used for detecting multiple potentially influential low outliers in a flood series. The WLS regression found that no basin characteristics could explain the variability of standard deviation. Consequently, a constant regional standard deviation model was selected, resulting in a log-space value of 0.91 with a MSE of 0.03 log units. Yet drainage area was found to be statistically significant at explaining the site-to-site variability in mean. The linear WLS regional mean model based on drainage area had a pseudo- Rδ₂ of 51 percent and a MSE of 0.32 log units. The regional parameter estimates were then used to develop a set of equations for estimating flows with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities for ungaged basins. The final equations are functions of drainage area. Average standard errors of prediction for these regression equations range from 214.2 to 856.2 percent.

System Dynamics approach is a powerful tool in water resources systems simulation for evaluating proposed plans and policies in development projects. In Aras River basin, existing water resources do not suffice increasing demand in the near future, thus construction of new reservoirs is under study. In this study, system dynamics approach is used to simulate the water resources system of Darehrood sub basin located in eastern part of Aras River basin. Performance indices are used to evaluate the alternative plans and policies.. Reliability, resiliency and vulnerability, the three performance indices used in study, are estimated using maximum value and mean value estimators mentioned in the literature. The results show that although using the maximum value estimators have been proposed in some studies, mean value estimators provide more useful information since their estimates reflect the performance of the system in all the states. Using these indices together with the results of simulation model, can provide managers and decision makers with useful knowledge of system performance and help them to select good alternatives.

A system that utilizes an ensemble of streamflow forecasts as input to the Truckee-Carson RiverWare© operational forecast model has been developed to provide operators and stakeholders with an ensemble of operational forecasts. This ensemble of operational forecasts allows users to estimate uncertainty and perform risk-based analyses to assist with operational decisions. The ensemble of streamflow forecasts are provided by the River Forecast Center's Ensemble Streamflow Prediction program which generates the forecasts based upon current hydrologic conditions and historic meteorology records. The streamflow forecasts are input hydrographs for the operational forecast model. The operational forecast model is run once for each trace of the ensemble streamflow forecast. During each run the model simulates daily operation of the river according to current basin policy. Select output is then collected from each run to be analyzed statistically, providing estimates of risk and uncertainty in the operational forecast. The RiverWare© Multiple Run Management tool is employed to facilitate the efficient use of the ensemble forecasts for daily operational decisions. This tool provides an automated process for performing multiple model runs with varying input and compiling select output within one file. An overview of the process and a sample application on Lake Tahoe precautionary release operations will be presented.

This paper summarizes the results of two similar studies of reservoir flood operations. The first study is a re-operation of Folsom Dam, California with outlet structure improvements and the potential of flood rules that are fixed or based on a combination of precipitation, snowpack, and ENSO conditions. Trade-offs between flood probabilities and water supply spill are estimated and analyzed using expected ranges of costs of levee failures downstream and the value of spilled water for water supply. The second study is a re-operation of Camanche Reservoir in central California to reallocate some flood storage for use in managing downstream environmental flows as well as urban water supply and hydropower purposes. Trade-offs between economic and environmental performance are estimated and discussed.

This paper describes the development of a robust optimization (RO) model for the management and operation of a reservoir for hydropower production. The robust optimization is used to deal with the data uncertainty. It does not seek to achieve global optimal but instead it looks for more consistent results by minimizing the variance of the optimal robust solution and thus leading to fewer programming issues due to data uncertainty. The robust optimization model applied to the hydropower production consists of a nonlinear programming (NLP) problem with two main objectives: minimize the quadratic difference between installed capacity and energy generated, and its corresponding variance. The model was written using the General Algebraic Modeling System (GAMS). The model was applied to the hydropower plant of SINOP, which will be built in Sinop city, state of Mato Grosso in Brazil, with an installed capacity of 400 MW and maximum storage capacity of 3,100 hm³, whose design is still in development. One special constraint to operate this reservoir is related to a variable maximum forebay water level, required to preserve seasonal ponds upstream of the dam. The ponds must be separated from the main reservoir during young fishes growing. Results are presented considering multiple inflow scenarios.

The Qezelozan-Sefidrood River Basin is an Iranian transboudary river basin, shared by eight provinces, namely Kurdistan, Zanjan, Hamadan, Eastern Azerbaijan, Ardabil, Tehran, Qazvin, and Gilan. Recent developments and the existing development plans in these provinces have triggered new conflicts between the riparian parties. This study shows how various fair allocation rules can be developed based on bankruptcy methods to resolve transboundary river problems in which the total demand imposed on river at a specific time and location in the river basin, exceeds the available water. Four bankruptcy methods, namely the Proportional (P), Adjusted Proportional (AP), Constrained Equal Award (CEA), and the Constrained Equal Losses (CEL) rules are applied to suggest fair allocation schemes for different scenarios, representing the possible future development and climatic conditions in the basin. To identify the most acceptable allocation scheme for each scenario, Plurality rule is applied. Results suggest that the CEA-based scheme is the most acceptable allocation under all scenarios.

This paper develops a stochastic fuzzy decision making method to solve a class of decision making problems which involve simultaneous uncertainty and ambiguity when screening water resources management alternatives. In these analyses, not only the performance value with respect to a specific criterion in a given alternative is uncertain, but also the performance implications of the given alternative may be vague with respect to the considered criterion by the decision maker. The integration between Monte-Carlo simulation and fuzzy decision making may provide a unique soft computing technique linking randomness and fuzziness together. Whereas the stochastic problem is mapped into a deterministic environment through the use of a Monte-Carlo simulation process, fuzzy decision making helps entail the linguistic uncertainty (i.e., ambiguity) in decision science. With this framework, the overall performance of a wealth of alternatives can be further evaluated, resulting in considerable reduction in the uncertainty and ambiguity in the decision making arena. Practical implementation has been assessed by a case study of the Sacramento-San Joaquin Delta in California in which the performance of four water export alternatives were evaluated to determine the satisfactory solution with respect to the environmental sustainability and cost-effectiveness criteria.

This study estimates tropical cyclone-generated storm surge levels for 2-year, 5-year, 10-year, 25-year, 50-year and 100-year return periods along the U.S. Gulf Coast. The study utilizes SURGEDAT, a Gulf of Mexico storm surge database, for statistical analysis. The most recent 111 years (1900-2010) of this 131-year dataset are analyzed, as this time period maximizes surge observations, while minimizing missing data. Return periods are calculated using the Pareto, Gumbel and Beta-P distributions, and the Huff-Angel and Southern Regional Climate Center (SRCC) linear regression methods. The Kolmogorov-Smirnov Statistic indicates that the SRCC method produced the best results. The SRCC method estimated basin-wide surge levels ranging from 2.67 meters for the 2-year return period to 8.20 meters for the 100-year return period. A K-means clustering algorithm was employed to separate Gulf Coast surges into 10 separate sub-regions. Surge levels for the 10-year, 25-year, 50-year and 100-year return periods were calculated for each sub-region using the SRCC linear regression method. The Southeast Louisiana/ Mississippi Zone generated the highest surge levels for each return period. Surge levels in this zone ranged from 2.72 meters for the 10-year return period, to 7.67 meters for the 100-year return period. These high surge levels are obviously driven by the extreme surges associated with Hurricanes Katrina and Camille. The lowest surge levels in the region were estimated along the West Coast of Florida. These results are useful for emergency management and disaster science personnel, planners, decision makers, stakeholders in various industries, as well as the scientific research community.

In 2011, the State of Texas experienced one of its driest years since 1917. In hindsight, this drought could have been predicted using a recently found novel association between earth's hydrological variability and lunar orbital pathways in tandem with the earth orbiting the sun. The finding of this association followed the formulation of the paradoxical hydrological stationarity problem, which was inferred from the study of long-term precipitation data in California. The current work uses 20th century's precipitation data at a cross-section of gauging stations in Texas and shows that specific water years in the last century, including 1917, had similar lunar orbital pathways that are associated with dry hydrological conditions across the State. Lunar orbital pathway information in the last century and out to the end of the 21st century was established utilizing data obtained from the National Aeronautics and Space Administration (NASA). The analysis is done in terms of both the total precipitation and the storm pattern during the identified water years. Both of these variables appear to be far from random and reinforce previous observations that the paradoxical hydrological stationarity problem points to deterministic solutions. Newton's law of universal gravitation is suggested to be the likely physical process behind the observed realizations, a subject of continued interest and investigation. This paper elaborates the methodology established and used to infer the predictability of the 2011 Texas drought and presents various analysis results. It also makes recommendations for concerted efforts to do further validation exercises regarding the predictability of hydrological conditions on a global scale wherever long-term precipitation data may be available. It also makes a call for real time validation exercises of this finding in the coming several years in order to build confidence and start to use it for various policy and decision making purposes.

One of the major challenges for planning and operation of complex hydrothermal systems is how to incorporate stochasticity in decision making; particularly, the stochasticity of inflows to reservoirs. The country of Brazil is subject to different climate regimes in different regions of the country. Consequently, great hydrological diversity is observed throughout the major watersheds. The Brazilian hydrothermal system consists of a completely linked network of 129 medium and large hydropower plants, 798 small hydropower plants, and 1469 thermal and 57 wind power plants, with a total installed capacity of 123,464 MW. The hydropower plants produce, on average, 91% of the total electricity consumed in the country, while the complementary thermal system is dispatched mainly during periods of drought. In our previous studies, we developed the HIDROTERM model to optimize the management and operation of the hydrothermal system. This deterministic model considers individual hydropower plants and is solved by nonlinear programming. The model is particularly useful for sensitivity analysis and has been applied to the planning and operation of the existing hydrothermal system. We now develop a new version of the model. The new model directly incorporates the stochasticity of the inflows in the formulation. The approach is based on a two-stage stochastic programming with recourse. The multi-stage inflow scenario tree is first built. The first stage is deterministic using inflow forecasts. The second stage branches out into possible scenarios. To reduce the size of the stochastic programming with recourse problem we are investigating different scenario tree reduction methods as well as methods that can be used to reduce the simulation time of the underlying hydrothermal model. The proposed methodology has been tested and verified on the Paranapanema basin, a representative subsystem of the Brazilian hydrothermal system.

Updates are being made to the CALVIN hydro-economic optimization model of California's intertied water supply and delivery system. These updates better reflect water demands, groundwater availability, and local water management opportunities. This paper focuses on updates to groundwater in CALVIN, which includes changing CALVIN groundwater parameters based on California Department of Water Resources' (DWR) California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM) and the United States Geological Survey (USGS) Central Valley Hydrologic Model (CVHM) model inputs and results. Two projects, using the respective groundwater models by DWR or USGS model as a base, are underway to update CALVIN's groundwater representation, specifically basin inflows, reuse, return flows, capacities, and costs. When these sub-projects are completed and analyzed, a CALVIN model with updated groundwater representation based on C2VSIM and CVHM will emerge.

With the increasing scarcity of water resources, the economic management of precious freshwater resources is also increasing. Water price is continuously rising in many urban in China. With the rapid rise of water price, there is a corresponding change in water consumption. Part of the family's water consumption declined significantly, also obviously reduced industrial water. The impact of water price on water consumption is significantly, but in the past a long time, urban water consumption projections did not consider the impact of water price. Therefore, it is need to study the influence of price-based forecasts on urban water consumption, improve the accuracy of forecasting and planning on urban water consumption. Based on the in-depth analysis of urban water consumption long-term forecasting model, the paper pointed out that the urgent need for the study on urban water consumption forecasting based on price elasticity. First, test and verify the law of water price and water consumption by use the data about the water price and water consumption in China from 2000 to 2007; Second, simulated the water price changes, water consumption varied, the lowest water consumption adjustment based on the L.D models by use the China actual data. The results show that: China's water consumption, water prices, the price elasticity of changes in the relationship shown in line with L.D model, the model can be applied to China's urban water consumption forecast.

There are many conflicts involved in the operation of a hydrothermal system mainly due to competitive uses of water. That is the case of São Francisco River located in the northeast region in Brazil. The hydro system in this region has an installed capacity of 10.7 GW and supports 13% of the Brazilian hydro electrical power. Due to the scarcity of water in this region the operation of this system has been questioned in the last few years. The competitive uses of water in this region are water supply, irrigation, animal raising and environmental protection. These demands can be attended by a proposed large water transfer system from São Francisco river to other watersheds in the region. The electrical sector is planning to review the reservoir operation rules in order to attend these demands. This paper presents results from a study conducted to evaluate the impacts of the hydro production caused by the multipurpose uses of water in the São Francisco River. The study was conducted by applying the HIDROTERM model, which is an optimization model that maximizes hydropower production and minimizes thermo production based on fossil fuels. A new objective function was added to the HIDROTERM model in order to evaluate the proposed water transfer system. The trade-offs among energy, water supply, irrigation and environment protection are presented, along with other relevant discussions.