World Environmental and Water Resources Congress 2008: Ahupua'A

This study investigates the water issues as they relate to social and economic development in Nigeria, West Africa. The study evaluates the quality of surface drinking water sources in selected highly polluted areas to define the extent of pollution. It accounts for human activities as they relate to water pollution and water-borne diseases, and identify both structural and non-structural Best Management Practices (BMPs) for pollution abatement. The structural BMPs are potential technology that could be manufactured in Nigeria. The study finally suggests a Water Access Awareness Program (WAAP) to educate the people on the problems.

This paper explores a few of the factors relevant to BMP practices and selection as affected by arid climate conditions, and provides a case study where evaporation rather than discharge was the principle detention facility outlet mechanism. It is intended to contribute to discussions on arid regions hydrology that are currently under way, particularly within ASCE's EWRI Urban Water Resources Research Council, and to stimulate dialogue regarding stormwater management practice in such areas. While BMP solutions seem by definition to have wide extensibility, it is not clear to the authors that BMP solutions are universally effective. Social context and prevailing infrastructure can make accepted practice in BMP technologies in one area inappropriate in another. The case study demonstrates control of discharge totally by evaporation in an arid region where this was preferred, but it is recognized that alternative measures might be preferred in regions where groundwater storage is an option or where evaporative losses are to be avoided. There is already some substance in the literature that reflects this kind of appropriate discrimination of preferred solutions, but there remains a significant need to extend and further develop this understanding.

The current availability of renewable water resources in the MENA region is just above 1000m³ per capita per year, a level that is regarded as representing "water scarcity". This represents the region as a whole and masks the complex water related issues that face the diverse countries of the region. Specific and well formulated water policies and national water strategies are required if the future demands for water are to be met. These should be assessed in the context of macro-economic policies and the opportunities that are presented through "virtual water" imports, elements which vary widely across the MENA region. Supply and demand management measures, legal and institutional issues also need careful assessment and integration into water strategies. Some progress is already being made. Black & Veatch, funded by the UK's Department for International Development, have recently completed a research project, on water demand management options and their integration into water policy and water resources strategies and these are also discussed in the paper.

30 well-established 240L bioretention mesocosms were used to investigate retention of dissolved nutrients by bioretention systems. 10 mesocosms were comprised of 80cm sandy loam, 10 of 80cm loamy sand, and 10 of pea gravel with 20cm of loamy sand. Half were vegetated with shrubs/grasses, while the other had no vegetation (barren). In our study, the mesocosms were loaded weekly with 45cm of tertiary effluent with high nutrient loads (23.2 m-yr^–1 hydraulic load at a flow-weighted average of 4.8 mg-1^–1 TP and 4.8 mg-1^–1 TN, or 1,090 kg-ha^–1-yr^–1 TP and 1,093 kg-ha^–1-yr^–1 TN). After 50 weeks of loading, cumulative TP retention was 92% in the vegetated loam, 67% in the sand, and 44% in the vegetated gravel. However. TP retention by barren media was 56% in the loam, 38% in the sand, and 15% in the gravel. Cumulative TN retention was 79% in the vegetated loam, 52% in the sand, and 43% in the vegetated gravel. In contrast, maximum TN removal by barren media was 21% in the loam. The increase in TP retention by vegetated systems substantially exceeds phosphorus uptake rates for plants, suggesting that other processes are involved. The increase in TN retention by vegetated systems also exceeds nitrogen uptake rates for plants, suggesting that denitrification is involved.

In a time of continuing urban sprawl, using stormwater best management practices (BMPs) to effectively control and treat stormwater remains an important topic. Rain gardens are one such BMP that qualifies as a low impact development. Rain gardens are an aesthetically pleasing option that reduce runoff volume and remove stormwater pollutants through the processes of infiltration/filtration, adsorption, evapotranspiration, and plant uptake. However, before choices can be made, performance specifications and maintenance requirements need to be developed. Monitoring programs are often used to evaluate the performance of stormwater BMPs such as rain gardens. Monitoring a large number of low impact development (LID) practices, however, is impractical due to the time and cost requirements and the large uncertainty in the performance results. It is of interest, therefore, to develop other techniques to determine the effectiveness of these infiltration practices. Infiltration rate is a key assessment parameter for rain gardens. Three additional methods for determining the infiltration rates of rain gardens have been developed as part of a tiered four level assessment protocol. The four levels of assessment in the protocol include: a visual inspection, infiltration capacity testing, stimulated runoff testing, and monitoring. The results can provide useful insight to proper design, operation and maintenance schedules to achieve stormwater treatment goals.

Five bioretention cells were studied from 2004 through 2007 in central North Carolina. They were located in Charlotte (1), Graham (2), and Rocky Mount (2). The former three cells were located in the Piedmont and therefore were underlain by clay-influenced soils. The latter two cells were located in the Upper Coastal Plain, which were sand dominated. The cells differed by vegetation cover, media type, media depth, and underdrain configuration. The Charlotte cell was 1.2 m deep and filled with a sandy-loam soil. It was drained by conventional underdrains and vegetated by trees and shrubs and covered by mulch. The Graham cells were 0.6 and 0.9 m deep, employed a proprietary soil comprised primarily of expanded slate fines, and had an upturn in the underdrain to create a sump to temporarily store water. The two cells were turf covered. In Rocky Mount, both cells were 0.9 m deep and used a sand fill media (98% sand). Both cells employed an upturned underdrain, but one cell was vegetated by turf grass and the other cell was vegetated by trees and shrubs and covered in mulch. Substantial data have been collected for the cells in Charlotte and Graham, while data collection in Rocky Mount is on-going. To date, all five cells, despite their many different design elements, have been shown to reduce nutrient loads and concentrations, and reduce outflow volumes, as compared to inflow volumes. Important implications of the research are a continued refinement of bioretention performance standards, confirmation that grassed systems perform comparably well to tree and shrub systems (at least in the short term), and the role of an upturned drainage system, particularly in a somewhat sandy in situ soil.

Chemical coagulation-flocculation systems are increasingly being used in construction stormwater treatment systems for the clarification of turbid runoff. Numerous coagulants and flocculants are available, but their application to stormwater is relatively recent, and there is little data available allowing a quantitative performance evaluation and comparison. This study presents a laboratory evaluation and comparison of common coagulants used for stormwater treatment. Jar tests were conducted using four different chemical coagulants, with synthetic 1000-NTU stormwater made up from soil samples from construction sites. Results demonstrate that coagulant performance varies considerably for a given soil, with optimum doses ranging from a few mg/L to over 100 mg/L, and that different coagulants have characteristic dose/response curves.

Constructed stormwater wetlands (CSWs) are considered to be an effective part of green infrastructure to improve stormwater quality, however further research is needed to validate the CSWs ability to reduce nutrient loads. Past studies on the Villanova University CSW under baseflow conditions showed Total Nitrogen and Total Phosphorous had approximately 72% and 78% removal efficiency (by concentration) in the fall, respectively. For storm events, the removal efficiency (by concentration) of Total Phosphorous was 38%, but the results for Total Nitrogen were mixed, with a 1% increase in concentration through the CSW. The facility was again under study beginning in summer 2007 to evaluate water quality and quantity of a mature CSW under baseflow and storm conditions. The results confirm the treatment capability of Total Phosphorous under storm and baseflow conditions, and show an improvement in treatment of Total Nitrogen. The present work links discrete storm and baseflow samples to begin to integrate the fate and transport of pollutants to fully validate the nutrient reduction benefits of a CSW.

Many BMPs undergo field monitoring to assess the ability of the BMP to meet water quality goals. This is typically accomplished using protocols that outline data quality objectives. Some of these objectives include a minimum number of storms, minimum storm depth, and flow rates or water quality volumes that span the operating range of the BMP. Typically during the data analysis, mass weighting is used to calculate performance efficiency on a load basis. However, considerations for the weighting of the storms, relative to the frequency of occurrence is typically not done. This can be problematic in that the collection of too many small storms may not reflect the ability of the BMP to perform for larger storms, or the collection of too many large storms could underestimate the relative performance of the BMP on a long-term basis. This paper investigates a method to weight the storms collected relative to the frequency distribution of the average annual daily rainfall. This method could be used in the development of sampling protocols and methods currently being established by committee through EWRI.

Seattle-Tacoma International Airport Third Runway Project in SeaTac, Washington, is one of the largest earth work projects in the country. The entire project is adjacent to sensitive receiving waters including wetlands and salmon-bearing streams making stormwater quality a top priority. Achieving compliance with the project National Pollutant Discharge Elimination System (NPDES) Stormwater Permit required an integrated stormwater management strategy which included aggressive implementation and maintenance of traditional best management practices (BMPs), installation of large stormwater storage ponds and the use of a relatively new flow-through water treatment technology termed chitosan-enhanced sand filtration (CESF). The case study will discuss project details including CESF technology basics, water treatment limitations, summary of water quality data and pollutant removal efficiencies, applicability of CESF technology to other types of construction projects and costs. The success of this project has been recognized by scientist such as Bill Nye, The Science Guy, publishers such as Forester Communications and local television broadcast news (KOMO TV — Seattle, WA).

China is now in her high speed development period of urbanization. However, a lot of problems appear recently that are concerned with the changes of ground surface in urban areas. The flooding and water logging happen frequently while groundwater level falls down. The use of penetrable pavements is one of useful measures to compensate the changes of urbanization. The paper, based on experiment and analysis of penetrable pavement projects in Dalian City, China, discusses the hydrological and environmental effects of penetrable pavement. Dalian belongs to the north seasonal rainfall zone. The most of annual rainfall occurs in the 4 month's rainfall season. Considering these natural conditions, the effect and benefit of penetrable pavement in urban areas is evaluated. The research results are helpful to make the decision how to extend this measurement and how to compensate the additional consumption for using penetrable pavement.

More then a decade ago, members of the Environmental and Water Resources Institute's (EWRI's) Urban Water Resources Research Council (UWRRC) identified a need to gather sufficient technical design and performance information to improve urban stormwater Best Management Practice (BMP) selection and design so that local stormwater problems can be cost-effectively addressed. As a result, the International Stormwater BMP Database Project was initiated. The U.S. Environmental Protection Agency (USEPA) initially funded the project through the UWRRC of ASCE via multiple grants, and in 2004, the project transitioned to a more broadly supported coalition of partners led by the Water Environment Research Foundation (WERF), and including the American Public Works Association (APWA) and the Federal Highway Administration (FHWA), as well as ASCE and USEPA. While the long-term vision of the project has remained the same, many significant improvements to the database have been made. This paper provides an overview of the overall database project for those unfamiliar with the project and identifies major changes that have been made for those familiar with the early stages of the effort. This paper provides an overview of the resources now available from the www.bmpdatabase.org website. Key aspects of these resources include enhanced tools to track BMP performance through improved data entry spreadsheets and a significantly revised project website. Additionally, an overview of the studies contained in the database, which now includes over 340 BMP studies, is provided. Several examples of how regional and state organizations have adopted the database to track their own BMP performance and improve reporting associated with BMP performance studies are provided. The presentation accompanying this paper will provide additional examples of how the database can be used as a tool for a broad range of entities involved in stormwater management and research or affected by National Pollutant Discharge Elimination System (NPDES) permits, such as public works administrators and engineers, state transportation departments, consulting engineers, and university researchers. Due to significant growth of the database and improvements in data analysis and summary products, the database is a scientifically-based resource that now offers relevant information and tools to all of these users.

Stormwater practices are being installed across the world and studies show they are not being properly inspected and maintained. If not properly maintained, stormwater practices will not perform as intended, but minimal guidance on maintenance procedures is available. In North Carolina, U.S.A., the North Carolina State University Cooperative Extension Service has developed a 1.5 day training and certification program that has certified approximately 500 design, local government, and landscape maintenance professionals and practitioners in stormwater practice inspection and maintenance. To date the response has been very favorable, as several communities now require the certification for anyone who designs and/or maintains stormwater practices. Officials with the state of North Carolina have incorporated designing for inspection and maintenance as part of their stormwater practice review.

The impacts of stormwater controls within headwater streams are rarely accounted for when Federal Emergency Management Agency floodplains are delineated even though stormwater controls, and specifically detention ponds, are often designed to control peak discharges from 10-, 25- or 100-year runoff events. Inconsistency in the maintenance of stormwater controls impacts their reliability for control of peak discharges, but it is hypothesized that if these facilities are properly and consistently maintained, their impacts on floodplains should be considered in their delineation. The City of Lenexa, Kansas is currently undergoing a study to develop a strategy for maintaining and improving existing detention facilities with the goal of refining floodplain boundaries, providing long-term stream stability, and improving water quality. As part of this project, an assessment was conducted to inventory existing detention basins within the study area by reviewing aerial/topographic mapping and as-built information combined with a field reconnaissance. It was found that a significantly greater number of basins existed within the study area than was originally anticipated. The impacts of the detention basins were evaluated using HEC-HMS and HEC-RAS models to better understand the function and necessity of the existing facilities, to determine the level of service of the existing basins and to determine their combined impacts on receiving streams from both a flooding standpoint and a geomorphologic standpoint. For the hydrologic analysis, an existing HEC-1 model was converted to a HEC-HMS model, and then modified to provide storage nodes that reflect the existing detention ponds. For the hydraulic analysis, HEC-RAS models were used to simulate the 2, 10, and 100-year design storms using the peak flow rates estimated by the HEC-HMS model. These analyses will be used to create a detention basin strategy that maximizes flood reduction potential for the 10 and 100-year design storms through improved maintenance of existing detention basins, retrofitting of existing basins, and the identification of locations that would be beneficial for new detention basins.

This paper presents the monitoring results of infiltration-based stormwater best management practices (BMPs) for a commercial development site in Aurora, Colorado. Although the Denver Urban Drainage and Flood Control District (UDFCD) has criteria for pervious pavement and for infiltration-based BMPs, these practices have not been widely used in the Denver Metropolitan Area, and very little monitoring data have been collected to evaluate the effectiveness of such practices. The site evaluated by the study described in this paper is a 9.35-acre parking area for a commercial retailer. The parking area consists of sections of pervious asphalt and pervious concrete pavement underlain by gravel infiltration beds as well as areas of traditional pavement which drain to bioswales. The bioswales are connected to the infiltration beds beneath the pervious pavement sections. Through a series of perforated pipes, monitoring of the site began in the spring of 2006, and over a two-year period, fourteen events have been captured. Monitoring has been conducted using automatic stormwater sampling equipment for collection of water quality samples from the bioswales and using Barologger level measurement devices to evaluate infiltration bed hydrology. Nine groundwater monitoring wells were installed to evaluate the effects of the infiltration-based BMPs on groundwater. Water quality samples and level measurements collected from wells have yielded groundwater quantity and quality data that complement the monitoring data from the bioswales and infiltration beds. Results of groundwater monitoring will be discussed in a forthcoming, separate paper due to space constraints of conference proceedings. This paper focuses on surface water hydrology and quality. Monitoring is scheduled to continue for a third year, and additional monitoring in the future (10 to 15 years) could be extremely valuable for evaluating performance of the system over time.

With the increasing need for the independent field testing of proprietary devices comes the importance of consistent data reporting guidelines to be used when reporting to regulatory agencies. The need for standardized reporting is underscored by the tremendous impact the range of factors can have upon testing results. These factors include the testing environment, experimental design, testing methodologies, statistical analysis, and data presentation. The need for the consistency is underscored by the complex influence these factors have upon performance results. A clear and consistent data reporting approach can ensure that these biases are minimized, well understood, and that representative field testing can be effectively evaluated by the regulatory agency. Data Reporting guidelines presented here were developed as part of the ASCE/EWRI Committee on Guidelines for Certification of Manufactured Stormwater BMPs.

Manufactured stormwater Best Management Practices (BMPs) are becoming an integral part of stormwater infrastructure, as well as a component of wet-weather flow technology. They are commonly used but there are few guidelines regarding the use of these manufactured devices. An ASCE/EWRI task committee was formed in May 2007 to develop guidelines for the certification of manufactured stormwater BMPs. The committee kickoff meeting was held at the EWRI 2007 Congress in Tampa, Florida. At this meeting, the scope of work was discussed, with the consensus being to focus on physical separation of particles for the full spectrum of stormwater-borne non-dissolved solids. Complex issues regarding testing and certification BMPs were identified, and six subcommittees were formed to address these issues simultaneously. These six subcommittees are: (1) Laboratory Testing, (2) Field Monitoring, (3) Scaling, (4) Data Evaluation, (5) Data Reporting, and (6) Maintenance. This paper provides the results of the Task Committee work to date (January 2008), including review of the existing test, verification, and certification procedures and protocols and identification of additional standards development.

Field-testing of unit operations and processes (nominally called BMPs) requires critical planning and implementation through all steps of the verification process from initial watershed selection through defensible statements of BMP behavior based on field verification results. The desired goals and outcomes must be known and designed into the entire verification process. A continual evaluation, quality assurance and feedback protocol must be part of the testing protocol. What are the basic component categories of a well-designed and defensible field-testing protocol? In general, while watershed processes can be categorized and modeled, each watershed is different and unique with respect to BMP loadings of hydrologic, chemical, biological and particulate matter (PM) quantities. We must recognize these challenges and collect sufficient representative data so that the role of such uniqueness can be quantified for the specific BMP or BMPs tested. These challenges are significant because at this time there are very disparate methodologies of PM protocols mat range from gravimetric index tests such as the traditional total suspended solids (TSS) method adopted from wastewater treatment evaluations, or the more recent suspended sediment concentration (SSC) method, index tests such as turbidity testing, to more fundamental methods of particle size distributions (PSDs). Each index method provides an indication of BMP performance with respect to PM; however a more fundamental, transferable and defensible methodology includes PSD and turbidity testing that is combined with a representative gravimetric index test for PM. The committee is envisioning developing a multi-tiered approach to field testing predicated on the intended utilization and rigor required for the defensible and transferable application of BMP performance results. This committee is focused on manufactured BMP separation of PM. It should be recognized that the entire gradation of PM should be representatively characterized for a BMP, in particular the suspended fraction because of the mobility and acute bio-availability of this finer fraction.

ASCE/EWRI has assembled a Task Committee on guidelines for certification of manufactured stormwater BMPs. A nine-member subcommittee for maintenance was tasked by the larger committee to develop maintenance guidelines for manufactured stormwater BMPs. The subcommittee has developed recommendations for manufactured BMP maintenance in the following seven areas: (1) designing for maintenance, (2) defining standard maintenance triggers, (3) defining maintenance fundamentals for all manufactured BMPs, (4) defining maintenance tasks by BMP design; hydrodynamic or filter design, (5) identifying entities best able to maintain manufactured BMPs, and training requirements, (6) identifying entities to train maintenance providers, and (7) reviewing recommended disposal techniques for captured pollutants.

Manufactured stormwater best management practices (BMPs) generally apply one or both of two unit operations to remove particles from stormwater runoff: hydrodynamic separation and filtration. Hydrodynamic separation is best used to remove sand particles, while filtration is used to remove organic particles as well as silt and clay. Many manufactured stormwater BMPs also have a chamber designed to remove floatables, or particles that are lighter than water. The numerous designs and multiple sizes of these manufactured stormwater BMPs suggest the need for scaling criteria to size and apply designs in the field. This paper reviews the scaling criteria research that has been completed, the research that may be adopted from other areas, and the needs for developing scaling criteria in manufactured stormwater BMPs.

In sewer layout design, most developed models are designed to determine pipe diameter, slope and overall layout to minimize the least cost for the design rainfall. However, these models cannot consider the superposition effect of runoff hydrographs entering each junction. The suggested Optimal Sewer Layout Model (OSLM) is designed to control flows and distribute the node inflows while taking into consideration the superposition effect for reducing the inundation risk from the sewer pipes. The suggested model used the genetic algorithm to determine the optimal layout, which was connected to the SWMM (Storm Water Management Model) for the hydraulic analysis. The suggested model was applied to an actual urban watershed in Seoul, Korea. By using the suggested model, the peak outflows at the outlet were decreased by approximately 20% than those of the current sewer layout for the design rainfall during 30 minutes.

This paper describes early results and directions arising from ongoing research into factors that affect the preferred balance between primary treatment and disinfection in a conventional wastewater treatment plant during periods of wet weather overflow. Despite the fact that national policy and regional regulations have required or implied use of these elements of treatment for decades, there remain some basic issues that are unresolved. In the context of a wet weather overflow event, the selection of an optimum point and manner for disinfection as it relates to the degree solids removal is one such issue. The factors that affect the choice of this point, particularly as reflected by the current state of microbiological understanding of quantification methods and of the influences of water chemistry on disinfectant behavior and indicator bacteria partitioning between solid and liquid phase components of the flow stream, are examined. Potential avenues for improved treatment practices are noted, and research directions are discussed.

The Milwaukee Metropolitan Sewerage District (MMSD) provides wastewater and flood management services for 28 municipalities (Figure 1 on the following page) within its 411-square-mile planning area. One of the challenges faced by MMSD was the need to understand the timing and volume of flow contributed by each of these municipalities through their local sewer systems to the MMSD's Metropolitan Interceptor Sewer (MIS). The MIS is the regional sanitary sewer system operated by MMSD that connects local municipal sanitary sewer systems to the two regional wastewater treatment plants and regional Inline Storage System servicing the Milwaukee metropolitan area. In 2004, MMSD began development of limited satellite municipality System Evaluation and Capacity Assurance Plans (SECAP) for each of the satellite municipalities it serves. The SECAP hydraulic evaluations were limited in that only those portions of the local sanitary sewer systems necessary to provide required information for the 2020 Facilities Plan project were analyzed. The 2020 Facilities Plan is the most recent generation of facilities planning undertaken by MMSD to determine what MMSD facilities are required to meet the needs of the region through the year 2020. Specifically, the SECAP project was to: 1 Identify satellite municipality system capacity deficiencies. 2 Estimate satellite municipality system bypass volumes and flow rates for selected wet weather events. 3 Summarize peak flows delivered to the MIS system for a selection of wet weather events.

The United States Environmental Protection Agency (USEPA) has identified a need to use proven methodologies to develop computer tools that help communities properly characterize rainfall-derived infiltration and inflow (RDII) into sanitary sewer systems and develop sanitary sewer overflow (SSO) control plans. To accomplish this goal, the USEPA entered into a cooperative research and development agreement (CRADA) in 2003 with a technology partner — Camp Dresser & McKee (CDM) Inc. — to develop a public-domain Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox. The CRADA also prepared a technical guide for analyzing RDII, performing capacity analyses of sanitary sewer systems, and developing SSO control plans using the toolbox. This paper describes the CRADA outcomes and individual tools in the SSOAP Toolbox to perform capacity analyses of sanitary sewer systems and develop SSO control plans.

With the implementation of Phase I and Phase II NPDES permits, many state DOT's have MS4 permits that require the mapping of the DOT-owned storm drain network as well as implementation of best management practices (BMPs) to fulfill six minimum control measures including public education and outreach, public participation and involvement, illicit discharge detection and elimination, construction site stormwater runoff control, post construction stormwater management in new development and redevelopment, and pollution prevention/good housekeeping measures. As partial fulfillment of the Island of Oahu's MS4 NPDES Permit (No. HI S000001), the State of Hawaii Department of Transportation, Highways Division (DOT-Hwys) has developed an Asset Management System (AMS) to provide program staff with tools for the efficient and effective management of information generated by the components of the Statewide Storm Water Management Program (SSWMP). The AMS is capable of housing and organizing vast amounts of data, providing the means for program staff to analyze this data through computerized processes and solutions. AMS will provide the following support to the Oahu SSWMP. This paper will document the challenges and successes that HDOT has had in the development and implementation of a comprehensive, web based asset management, system.

This paper presents a prototype decision support system (DSS) that can be used to analyze municipal water portfolios using science-based climate models and regional scale urbanization scenarios. We present a system dynamics (SD) DSS, loosely coupled with a geographic information system (GIS) for water portfolio scenario analysis for Mesa, Arizona. The application demonstrates a multi-scale, modular, spatial framework for downscaling a regional dynamic water budget to the specific water portfolio of the City of Mesa. Climate change, population growth, surface water allocations, and groundwater supplies are calculated from WaterSim, a regional DSS developed at the Decision Center for a Desert City at Arizona State University; Mesa's specific water portfolios are generated via a portfolio module that extends the WaterSim framework to include city-scale demands, conservation estimates, "water-banking" credits, and multi-institutional constraints. The portfolio module connects a regional supply module to local and regional demand modules so that meaningful, scenario-based exploration of the city's water assets can be examined for adequacy and risk of shortages. In particular, conditions of drought, climate change, population growth, urbanization, and land-use change are simulated to reveal robust portfolio allocations that can better guarantee adequate water supplies with low cost and low risk of shortage under a broad range of conditions. Our scenario framework classifies scenario models into exogenous factors, policy options, and outcome metrics to systematically assess the key sensitivities of Mesa's water supply portfolio.

Urbanized semi-arid regions experience a significant amount of dry-weather flows in the form of return from excessive irrigation on suburban lawns. These dry-weather flows also carry significant amounts of nutrients from household fertilizers, which are discharged to receiving water bodies. These nutrients cause unsightly algal growth sometimes known as "urban slobber," that result in oxygen depletion due to organic matter decay. These flow rates can constitute a large component of dry-weather flow in urban streams. The conditions of semi-arid climates are conducive to turn these flows into a more visible nuisance than in humid regions. This paper explores the application of LID technology to manage dry-weather flows in semi-arid climates. LID's infiltration-based controls can be deployed to intercept and treat nutrient-laden excess irrigation flow. The concept is illustrated in a subdivision in Los Angeles, California area by applying the LIFE^TM model developed by CH2M HILL for simulation of LID hydrology.

The Low Impact Development (LID) techniques have been found to be advantageous in mimicking the pre-development hydrologic regime of urban and developing watersheds by attempting to preserve or restore the components hydrologic cycle. LID applications are common in humid climates in the northwest, mid-west and eastern portions of the United States but have been limited in the semi-arid climates of southwestern states due to some hydrologic issues. In this paper, a thorough evaluation of alternative approaches to stormwater management has been conducted using CH2M HILL's LIFE^TM model for a case study in California. This case study provides a brief summary of the results of the LID application and outlines considerations for implementing strategies to reduce the effects of development tand a better understanding of the benefits of implementing LID techniques to minimize the effects of development on stormwater pollution, stream bank erosion, and habitat degradation.

Although the application of real-time and dynamic controls is commonplace in wastewater and combined sewer system management, the use of on-site dynamic control systems for stormwater has been limited. The availability of low cost, highly functional, internet accessible, programmable logic controller systems and single board computer platforms and a new breed of large diameter, lower cost, low maintenance valve systems are making real-time and dynamic controls viable options for both new construction as well as retrofits of stormwater systems. The inclusion of dynamic control systems in on-site stormwater systems provides designers with an effective tool for meeting increasingly complex stormwater suite of goals by retaining water as close as possible to where it is generated and releasing it over an extended period to minimize the potential effects from stream ecological and morphological perspectives. Typical stormwater analysis and modeling is focused on developing designs that passively achieve stated goals; however, passive systems rarely represent optimal solutions. Dynamic systems are particularly well suited for complex situations where timing, duration of flow, peak discharge, volume reduction and reuse, and water quality are critically important. This paper focuses on describing the state-of-the practice, recent research by the authors, and new directions in applications, design, and equipment. Innovative applications that will be described include integration into low impact designs, flow-duration control, integration of embedded stormwater models, adaptive management approaches, water quality treatment optimization, and reuse. Case studies where such implementations have been explored as discussed.

The County of Maui's Wastewater Reclamation Division (WWRD) is recognized as a water reuse leader in the State of Hawaii. This paper will track the development of the WWRD's water reuse program from the early 1990's to its current status of playing an important role in sustainable water resource management in Maui County. The objectives of Maui's water reuse program are to supplement Maui's limited potable water supply and to reduce the use of injection wells for effluent disposal. Recycled water is reused from all five of the County's wastewater reclamation facilities and significant distribution systems have been constructed in south and west Maui. Recycled water is now used for a wide variety of purposes including landscape irrigation, agricultural irrigation, cooling, fire control, composting, toilet flushing, environmental enhancement and construction purposes. The initial primary factor driving Maui's water reuse program was a concern that the use of injection wells for effluent disposal was the main cause of periodic seaweed blooms that occur in Maui's coastal waters. While this concern still lingers, increased development and the lack of available fresh water have shifted the primary driving factor to more of a water supply issue. Recycled water is now considered an extremely valuable resource in Maui County and as a result, developers are funding expansions to Maui County's recycled water distribution systems. These expansions will benefit Maui's community and environment through potable water savings and the reduction in the use of injection wells for effluent disposal.

Given the magnitude of the threat to water quality posed by microbial pollutants in urban stormwater runoff and the untested potential for their removal in bioretention systems, the objectives of this research are to evaluate the capture and destruction of E. coli O157:H7 strain B6914 (as a pathogenic indicator) from synthetic urban stormwater runoff by conventional bioretention media, and to examine the potential of iron oxide-coated sand (IOCS) for enhancing bacterial removal. The results of these column experiments indicate that conventional bioretention media achieved approximately 80% removal of E. coli under the test conditions. Coated iron oxides enhanced bacterial adsorption through surface charge modification, increasing bacterial removal to 99%. However, the die-off rate of trapped cells in conventional bioretention media was far quicker than in the IOCS as studied. More than 99.98% of B6914 cells attached to conventional bioretention media died off within one week. Therefore, conventional bioretention media have a greater potential to render the process sustainable.

Pathogen concentrations in streamflow are commonly reported as a significant cause of water quality degradation throughout the world. Research has begun to attempt to model pathogen fate and transport, primarily through surface runoff mechanisms. A significant component of pathogen movement to streams commonly identified but not explicitly simulated in many models is pathogen movement to the subsurface, which can be important in several scenarios such as tile drainage systems. As colloidal contaminants, pathogens such as E. coli tend to become physically trapped in the soil matrix but can move quickly through soil macropores. In fact, concerns exist about the rapid transport of contaminants, such as pesticides, pathogens, and nutrients, from the soil surface to ground water through macropores. Recent research suggests short-circuiting or direct hydrologic connectivity between macropores and subsurface drains. The objective of this paper is to provide an overview of the current research regarding the fate and transport of E. coli through soil macropores and into subsurface drain systems. This paper reports early results from the first year of a multi-year study funded by the USDA Cooperative State Research, Education, and Extension Service as part of the their National Research Initiative program. Field experiments to document short-circuiting by macropores are described and also laboratory data is presented from soil column experiments, capable of simulating surface-connected macropores, with artificial subsurface drainage boundary conditions. These column studies generated information regarding the importance of directly connected macropores on pathogen transport to subsurface drains.

Pathogenic microoganisms can cause disease in humans exposed to contaminated recreational waters. New Hampshire uses enterococci as the fecal indicator in estuarine and marine recreational waters. Stormwater runoff is the most significant source of bacterial pollution in NH, and several types of routinely installed stormwater control systems are ineffective for removing enteroocci. This study addresses the performance of eleven treatment system designs on enterococci populations during storms. Water samples were collected during storms from eleven treatment systems under controlled conditions and enterococci were enumerated using EPA method 1101.6. Some systems appeared to be sources while others appeared to remove enterococci from runoff. Enterococci concentrations exhibited marked seasonal trends, peaking in August. These results suggest elevated enterococci concentrations are present in wet treatment systems between storms, resulting in increased concentrations being discharged into receiving waters with runoff from storms. Ongoing studies are designed to better characterize enterococci dynamics between storm events.

Coastal towns traditionally discharge stormwater containing bacteria and pathogens to the ocean via ocean outfalls, increasing the potential for serious diseases to recreational swimmers. To combat this risk, an innovative coastal BMP, a Dune Infiltration System (DIS), was designed and installed at two locations in Kure Beach, N.C. to divert stormwater from outfalls into the dunes. Post-construction monitoring of these systems during 25 storm events in 2006 showed that this design was economically and technically feasible, because 97% of the stormwater was diverted into the dunes, the dunes remained structurally stable, and Enterococcus concentrations entering from the outfalls were reduced by over 97%. However bacterial transport surrounding the system remained poorly understood, which limited the certainty at which this system could be recommended for further implementation. Therefore, a series of additional water table and water quality wells were installed at each of the systems, and in a nearby control dune, during the summer of 2007. After six-months, bacterial concentrations in the groundwater at the dune-beach interface near the dune infiltration sites are similar to that of the control area.

An integrated XP-SWMM and TUFLOW modeling framework was used to simulate flood propagation and evaluate the effectiveness of flood mitigation scenarios for the James Madison University (JMU) campus which had experienced frequent flooding historically. A flood mitigation scenario was developed as a combination of new relief pipe system to divert runoff from the off-campus drainage areas and an enhanced drainage system near the campus' outlet point. The developed flood mitigation scenario was simulated to evaluate its effectiveness. The simulated maximum flood depths for this scenario showed significantly decreased flood propagation and accumulation. The 2D visual interface for flood propagation comparison was very effective in terms of communicating the flooding consequences at critical flooding locations to the campus stakeholders.

The EPA's Experimental Stream Facility (ESF) represents an important tool in research that is underway to further understanding of the relative importance of stream ecosystems and the services they provide for effective watershed management. The ESF is operated under the goal of supporting the integration of risk assessment and management research objectives for water quality protection with controlled studies designed to characterize how streams react to and process emerging contaminants and stressful mixtures. The engineering aspects of the ESF set-up are described that allow for a balance between controlled laboratory conditions and the natural variability that is inherent to stream ecosystems, and that are required for adequate ecological simulation. Flow distribution is configured so that real stream water is delivered to eight mesocosms allowing for natural and optimal colonization while controlling for water residence time and hydraulic properties of riffle microhabitat. Single contaminants or stressful mixtures can be precisely dosed. Characteristics such as light intensity, influent water quality, and streambed substrate type can be manipulated within and across studies. Each ESF study provides information on ecosystem structure and function that can be used in relation to the development and testing of new indicators of ecological stress, water quality monitoring technologies, and water quality management methods and models.

The focus of this research is the impact of green roofs on urban stormwater quality and builds on a laboratory study that evaluated several potential green roof media to produce a mix that produced the "best" overall reduction in pollutants from simulated rainwater. Because of the limitations of the laboratory testing, this second phase (field test) was performed. A second purpose was to determine if this actual media mix would support plant life with minimal maintenance. The third question raised by the researchers was whether the green roof, at the low concentrations often seen in many pollutants in wet and dry deposition, could remove these pollutants. If not, was the green roof at least "chemically neutral" (e.g., did not remove or add pollutants to the runoff, such as those added to rainwater by passage over a galvanized metal roof?) The field study showed that, during the early life of these roofs, water quality from the green roofs was comparable to the control roofs and better, with the exception of phosphorus and added color, to that of the galvanized roof. The increase is color is believed to be from washout of the organics in the media. Plant development on these roofs has been very slow, probably due to the lack of added fertilizers and minimal organic matter; however, the water quality benefits may substantially outweigh the need for rapid plant growth.

On-site integrated water management has become one of the critical elements for protecting our water and treating it as a useful resource. Water conservation, capture, and reuse can help maintain a supply of water for current and future water needs. Preventing excessive quantities of runoff while maintaining the quality of surface waters can reduce or, in some cases, eliminate pollution from entering our natural drainage areas and limit hydromodification thereby protecting the ecological functioning of our natural receiving waters (rivers, streams, lakes, and wetlands). Despite the current regulatory environment, there are inconsistencies in the ability to successfully implement on-site integrated water management. Reasons for this include the necessity for regulators to approve new approaches (e.g., new road standards, site clustering), a change in designs standards, consideration of whole-life cycle cost, permit reviewers must have proper training and approved procedures, and the public must become more educated in stormwater management. While it is hoped that developers will recognize the validity and marketability of integrated water management, one of the largest impediments to implementation is the lack of incentives to encourage developers and builders to use integrated water management techniques. It is necessary to focus research on tools that lead to the successful adoption of on-site integrated water management, in particular methods that may condition and encourage public, developer, and builder acceptances of this approach. A watershed sustainability index based on holistic water management strategies that provide a framework for evaluation and a transparent rating system for new and redevelopment projects would be developed in this research effort. The watershed index, created through an expert panel, would define a set of standards and apply a numerical "credit" method measuring the degree to which the standards are met. The standards would be based on low impact development techniques such as integrated site design and decentralized stormwater controls that value greater flow attenuation, larger runoff volume reductions, and extended runoff duration while also minimizing the generation and transport of stormwater pollutants. The index would use an independent, third-party verification process to "score" a development's design and build based on on-site integrated water management and incorporation of multiple benefit techniques. Watershed managers, regulators, and developers would be able to estimate the number of credits earned as a measure of effort to minimize land development impacts on hydrology and water quality.

Part 2 of this two part series is an application of IDEAL, an object based post construction hydrology model, to water quality prediction that is suitable for use in cities throughout the US. Example prediction is made of the impact of selected LID concepts and treatment train Best Management Practices (BMPs) for Greenville, SC for which the model was developed. Additional applications are shown based on conditions for Albany, NY; Austin, TX, Baltimore, MD; Honolulu, HI, Salem, OR; Tallahassee, FL and Tulsa, OK. Local rainfall and soils information is used in the model predictions. Comparisons of sediment and nutrient loadings are made for multiple suites of treatment trains as well as for conditions having no BMPs. The results of this modeling effort are intended to show how varying climates and soils impact the effectiveness of varying treatment trains. Low Impact Development (LID) concepts and BMPs modeled by IDEAL include disconnecting storm drains, use of water barrels, bioretention cells, bioswales, sand filters, and VFS. Comparison can be made between the use of LID concepts and BMPs with the more traditional wet and dry ponds.

Part 1 of this two part series is an overview of IDEAL, an object based program developed in Microsoft® Visual Studio.Net to predict the runoff and pollutant loadings in urban post construction watersheds. IDEAL has the capability of predicting distributed source area generation of runoff, sediment, nutrients, and pathogens in post construction watersheds and route those through channels and structural BMPs. Procedures are also available to apply the model to the urban fringe with construction and agricultural source areas as well. The user interface uses a graphic user interface (GUI) with drop and drag capability to generate large numbers of subwatershed source areas, conveyances, and BMPs arranged in treatment trains. The limit on numbers and sizes of subwatersheds that can be used is primarily computational time and appropriateness of the conveyance objects. BMPs are modeled with process based algorithms that take into account mass continuity and the processes of infiltration, settling, and sorption for chemicals and pathogens as well as mortality and growth for pathogens. Deposition of human and wildlife source pathogens on BMPs is also calculated. Using probabilities of rainfall amounts, seasons, and infiltration characteristics, annual averages are computed for loadings at any point on the watershed. Interarrival time of storms is also used as a factor. An example model computation is given.

An empirical, dimensionless-hyetograph that relates depth and duration, and thus whether a storm is front loaded, back loaded, or uniformly loaded, based on 92 gaging stations for storms known to have produced runoff is available for Texas. Statistical characteristics of storm interevent time, depth, and duration, based on analysis of hourly rainfall data for 533 rain gages are used to "dimensionalize" this hyetograph and produce a set of simulated storms. These simulated storms are analyzed to generate a set of rainfall intensities, and these intensities are compared to global maximum observed rainfalls, intensities estimated using the National Weather Service TP-40, and HY-35 publications, and a current Texas Department of Transportation design equation. The simulated storms agree well with the other methods for rare (i.e. 90-th percentile and above) occurances and lie within the global maxima envelope. The simulated results are quite different for common (i.e. 50-th percentile) events.

Construction projects often expose large amounts of soil to the erosive forces of wind and rain. These areas must be stabilized and vegetation established before a Notice of Termination can be submitted to regulators. Quarries face many of the same issues with regard to stabilization of spoil piles and areas disturbed by mining. The objectives of this project were to compare the stabilization performance of two types of compost top dressing (low and high organic matter), a wood based hydromulch, and seeded bare soil and to determine the amount of sediment and nutrients exported from each type of treatment. Ten test plots (8 feet x 40 feet) were constructed on a spoil pile of a quarry located in Parker County, Texas. These plots were outfitted with runoff capture systems to collect all runoff from each plot. Water quality and quantity data were collected for 10 storms during the first year after installation. Compost mixtures were most successful at establishing vegetation, with almost full coverage after about four months. The hydromulch plots took much longer, with full establishment taking almost a year. The seeded bare soil plots had little vegetation even after a year. Runoff coefficients for the two types of compost were similar and about half that observed for the hydromulch and control plots, which were not significantly different. Compost reduced sediment discharge compared to bare plots by about 97%. The hydromulch was less effective than the compost treatments, but still reduced the TSS load by about 75% compared to bare plots. Even though both treatments reduced the load of total phosphorus discharged, dissolved phosphorus loads from compost treated plots were higher than from bare soil or hydromulch plots.

An overview of SEDPRO is given and used to illustrate impacts of changing land use on the environment during urban development. Its use is illustrated for selected watersheds within a rapidly developing area (Greenville County, SC, USA) Basic concepts and development of this innovative model are described to provide an understanding of the approach and limitations. Enhancements over the widely distributed SEDIMOT II and SEDIMOT III models include a graphical interface that features drag and drop placement of subwatersheds, best management practices (BMPs), and conveyances. This feature allows the user to place BMPs at points throughout the watershed and evaluate trapping efficiency of individual BMPs as well as the entire treatment train. Additional BMPs included are sand filters, bioswales, and engineered devices. It also can be used on any order watershed, not just the 3^rd order allowed in SEDIMOT. SEDPRO is used in the paper to illustrating the impact of alternative land uses and different types of construction.

Stormwater sampling by automatic samplers and the comparability of the suspended sediment concentration (SSC) and total suspended solids (TSS) methodologies have been a source of debate. Questions include whether autosamplers can pull up the larger, heavier particles found in stormwater, if automatic sampling has a particle size distribution (PSD) range limitation, and whether TSS and SSC recoveries are comparable. This research examined the protocols, limitations, and associated errors for solids determination. The autosampler was examined for its ability to sample simulated stormwater repeatably and accurately at various elevations above the water surface and within the water column, including the effect of PSD at all heights. Sample processing and splitting by churn and cone splitters were investigated for accuracy and repeatability in obtaining subaliquot volumes and representative PSD. Finally, two TSS methods and SSC were examined for recovering a known concentration and the comparability of the inter- and intra- methodologies.

Understanding basics of unit operations and processes (UOP) are fundamental for design, analysis and monitoring of Best Management Practices (BMP) for urban runoff pollution control. In physical separation processes such as hydrodynamic separation and filtration, particulate size plays an important role. Performance of these systems typically is evaluated by removing the mass of the particulate pollutants. In order to select the appropriate technology and design unit adequately to meet the desired performance, particle size distribution for the pollutants is one of the most critical physical characteristics to investigate and to be understood.

A very wide size range of particulate matter (PM) transported in urban stormwater poses significant challenges to sampling, analysis and control. In addition, mis-application of particle analysis often have the potential to cause misrepresentation of hetero-disperse PSD in urban stormwater by failing to characterize the entire gradation; or are carried out after sample holding time (< 12 hours) has resulted in natural coagulation and flocculation to occur. A methodology is developed which parallels particle size analysis from geotechnical engineering to characterize event-based size distribution of PM transported in urban stormwater by sampling and also analysis of the entire PM size range transported in runoff. This paper presents the non-colloidal PSDs for event-based size distribution of PM ranging in size from 1 μm to larger than 24,500 μm transported during urban runoff events. Through a literature review, the PSD results in this study were compared to those PSDs in urban runoff previously published in the literature with details of sampling and analytical methods employed. In order to demonstrate the validity of stormwater PSD results, mass balance error analysis, requiring a 90% mass recovery, was carried out for each monitored event. While the non-colloidal PSD results in this study demonstrate that urban stormwater transports PM in size ranging from 1 μm to larger than 24,500 μm, PSDs from the literature focus on more limited size ranges. With the common stormwater application of automatic samplers appropriately developed for less dense suspended floes from steady wastewater flows, the coarser fraction of the gradation is truncated by such sampling, in particular for source area runoff. Additionally, sample holding times that allow coagulation and flocculation truncate the suspended fraction of the gradation. Ultimately, urban environs and receiving water are impacted by the entire PM gradation, but through differing mechanisms and time scales; resulting in the need to characterize and control the entire gradation. Because of the hetero-disperse nature of runoff PM, the suspended fine fraction is appropriately characterized and controlled based on particle volume/number and in contrast, on a gravimetric basis for the coarse fraction larger than 75 μm.

Stormwater treatment device selection is largely governed by regulatory compliance. Often stormwater management strategies are selected to comply with a regulatory performance requirement rather than being designed based upon actual performance characteristics of the systems. While technical performance evaluation of stormwater treatment devices is an evolving science, regulatory guidelines struggle to keep in step with regional demands for information. A discussion of the origin of a TSS performance standard and its potential limitations is presented against a comprehensive statistical analysis of pollutant relationship patterns of influent and effluent water quality across a range of stormwater management practices. Complex pollutant relationships, or lack-there-of, suggest that In the future we will need to integrate our stormwater designs into the building blocks of regional watershed improvement strategies with careful attention to altered hydrology. One effective means for addressing this is by implementing innovative BMPs employing some form of filtration or infiltration mechanisms. Selection criteria that possess a foundation in regional watershed protection objectives need to be advanced using standards of performance that examine the fundamental causes of watershed impairment, namely altered hydrology.

The Lower Colorado River Authority-San Antonio Water System Water Project (LSWP) is a cooperative effort between two regions in central Texas. The general project area in south central Texas is shown in Figure 1. The LSWP would conserve and develop water in the Lower Colorado River (Texas) basin in three ways: 1) Reduce agricultural irrigation water demand through conservation practices, efficiencies and measures. 2) Capture and store excess and unused river flows. 3) Use limited amounts of groundwater for agriculture in the Lower Colorado Fiver Basin when surface water is not available.

Access to an assured supply of fresh water is critical to sustain ourselves, our communities, the economies in urban and rural areas that have grown as a result of our development of the West and for the environment that we live in. We have developed some of the largest economies and population centers in the world in this semi-arid climate subject to climate variation, aridity and drought. Forecasts are for substantial population growth, sustainability and expansion of those economies and expectations of a vital ecosystem will place even greater demands on our natural resources across the West. At this time, we are over-subscribing the capacity of these natural water systems and shortages are being experienced. The water manager must consider a range of adaptive strategies to create an acceptable balance of solutions to meet those multiple needs in this highly political and contentious setting.

The Sydney Metropolitan area is currently undergoing significant expansion. At the same time, the effects of climate change are already being felt in Australia, with a severe drought driving the need to provide water, wastewater, and stormwater service that new development using an integrated and sustainable water resource approach. The type of development that presents the greatest challenges as well as opportunities from a water service standpoint is infill growth. In the Botany Infill Growth Area in Sydney, which incorporates the Wolli Creek, Green Square, and Sydney Airport areas, rapid commercial and residential development is occurring, including many high rise apartment buildings. As developers move forward with their plans, Sydney Water Corporation is developing an integrated strategy for providing water, sewer, and stormwater services to the area. This strategy will support decisions on development approvals, as well as providing SWC with strategic direction to move forward with sustainable integrated water cycle management.

As a proactive effort and as part of its NPDES MS4 program, Hawaii Department of Transportation, Highways Division (HDOT-HWYS) is conducting an Island-wide feasibility study for retrofitting its existing MS4 system on the Island of Oahu that discharges to the receiving waters listed on the Section 303(d) of the Clean Water Act. The targeted pollutants include sediment, siltation, turbidity, and/or trash. The retrofits are to include both source-control and stream-based control as well as maintenance related best management practices (BMPs) designed to improve water quality of the receiving streams, bays and ocean. Major objectives of the study include: 1 Identify and evaluate potential pollutant sources from HDOT MS4 that may cause storm water pollution and stream degradation; 2 Identify management measures related to HDOT Highways activities for the pollutant reduction and reestablishment of stream stability; 3 Identify potential opportunities for installing permanent BMPs controls within HDOT right-of-way; 4 Rank and prioritize management and control BMPs identified in the study.

Protecting environmental quality requires a comprehensive approach that heavily relies on our ability to confidently predict or forecast impacts, evaluate the ability of natural systems to absorb impacts, and determine the combination of options that will provide an acceptable level of protection and/or restoration. These forecasts, when accepted, can help stakeholders to understand the potential cost or implications of restoration options and guide the development of effective protection strategies that can mitigate and prevent adverse impacts. Forecasts, which are typically based on combinations of modeling and analysis, must be designed to be sensitive to changes in the watershed and to in-stream responses. The difficulty with forecasts is that they are just predictions based on what we know now and what we believe might happen in the future. That is why environmental protection studies emphasize rigorous science-based approaches that can build confidence in forecasts. Building on an extensive body of relevant studies in the Los Angeles region, including monitoring, model development, and regional model parameterization efforts, this study is designed to develop and apply a Best Management Practice Decision Support System (BMPDSS) for the evaluation of alternative storm water best management practices (BMPs) and Low Impact Development (LID) methods. The system allows managers to evaluate the ability of various BMP scenarios to provide necessary flow volume and pollutant load reductions for Total Maximum Daily Load (TMDL) implementation and optimizes the scenarios based on benefits and costs. The approach is designed to provide guidance for a public incentive plan for implementing onsite BMP/LID techniques. The framework developed in this study provides a technically defensible and repeatable basis for evaluating quantitative measures associated with alternative BMP implementation plans. The BMPDSS represents an advanced method for simulating BMP processes and analyzing benefits (e.g., load reductions). Results of this study provide an interesting glimpse into the most relevant and economical BMPs for typical land uses in the Los Angeles watershed.

Imperviousness has traditionally been a principal calibration parameter for collection system models. The 2007 publication of the National Land Cover Database impervious surface raster dataset, and in Massachusetts, a 1-m statewide impervious surface raster dataset, mean that imperviousness for United States urban collection systems is now readily computed. Calibration can instead focus on determining the transfer fraction from impervious to pervious surfaces. For citywide sewer and drain system models in the city of Boston, average measured imperviousness for storm drainage was 50 percent in neighborhoods with separated sewers. Model calibration yielded an average transfer fraction of 67 percent, resulting in an effective imperviousness of 17 percent. In portions of the city with combined or partially separated sewers, measured imperviousness was 72 percent. The calibrated average routing fraction was 66 percent, yielding an effective imperviousness of 25 percent. These results demonstrate that calibration to measured runoff remains critical to model development, as a high fraction of flow is routed from impervious to pervious surfaces. Methods for estimating transfer fractions exist, but further study should evaluate patterns and differences among urban areas.

The combined sewer overflow to Downtown Seattle's water front has been a problems for many years. The City has been evaluating different strategies to reduce the stormwater flows into City's infrastructure. One of the strategies is to evaluate low impact development (LID) alternative such as green roof retrofit, bioretention and porous pavement or the combination of any of them. This paper compares various LID models used to perform stormwater evaluations for Seattle's downtown basin. All models are running for continuous simulations for 29 year — 5 minutes rainfall data. Uncertainties associated with each model run are setup to assess the reliable reduction of stormwater flows.

Unit hydrographs are developed for a specific watershed using two basic approaches. If unit rainfall-runoff data are available, then numerous techniques can be applied to estimate a unit hydrograph from the data. If no data are available, then methods of synthetic hydrology must be applied. Current practice is regionalization of measured behavior used to transfer known hydrographs (or other hydrologic entities) from a location where measurements are available to unmonitored watersheds. The regionalization involves determining time parameters for the unit hydrograph procedure, which may include time to peak, time base, or time of concentration. Regionalization also involves development of regional regression equations for time parameters, watershed and/or rainfall characteristics. The principal elements required for the synthetic approach are the determination of characteristic loss features (loss model) and characteristic response time (unit hydrograph model). The authors observe that even if the temporal redistribution of excess rainfall is performed using hydraulic models, which is certainly feasible and often the most appropriate approach, then there is still need to understand how to convert the rainfall signal into an excess rainfall signal, and this will be accomplished with some kind of loss model. In the collective literature losses are correlated with watershed soil properties, while the characteristic response time is associated with physical characteristics such as watershed drainage areas, main channel and overland flow slopes, characteristic lengths, and characteristic velocities. Unit hydrograph parameterization was examined based on topographic information and simple loss models to predict the runoff volume, rate and timing with minimal watershed characterization, using data readily available to drainage engineers. Results from the approach were compared with observed rainfall-runoff responses and are reported herein.

Stormwater modeling in urban areas has risen to a high level of accomplishment, yet many improvements and research needs remain. This paper summarizes a foundation-type conference on the state-of-the-art of urban stormwater modeling, held in July 2007. Conference highlights and research needs are provided.

Continuous hydrologic modeling for a watershed involves characterization of a series of hydrologic processes affected by numerous factors over a long time period, which consists of both wet and dry conditions with/without rainfall. The complexity of those processes and their cumulative effects, and the lack of intensive long-term monitoring data, often prevent a modeler from effectively identifying the underlying processes and mechanisms, as well as accurately estimating the relevant hydrologic parameters. To circumvent this difficulty, a modeling strategy that combined event and continuous hydrologic modeling was implemented in this study. The fine-scale event hydrologic modeling, supported by intensive storm data, was used to improve the coarse-scale continuous modeling by providing more accurate and well-calibrated parameters. Two different rainfall-runoff models: the soil moisture accounting (SMA) and the SCS curve number (SCS-CN) models in HEC-HMS were utilized and discussed. In an application to the Mona Lake watershed in west Michigan, the Watershed Modeling System (WMS) and HEC-HMS were coupled for processing spatially-distributed GIS data, delineating the watershed, computing geometric and hydrologic parameters, and implementing hydrologic modeling. Several rainfall events were selected for calibrating/verifying the event model and identifying the related parameters, which were further used in the continuous hydrologic model. Two methods: normalized objective function (NOF) and modeling efficiency (EF) were utilized to quantify the goodness-of-fit between simulated and observed hydrographs and evaluate the model performance. Results from this study reveal that the joint event and continuous hydrologic modeling can be effective, as it takes full advantage of different hydrologic approaches and available data, and improves the overall quality of watershed hydrologic modeling.

The water quality of Onondaga Lake, NY has been compromised by a 100-year history of municipal and industrial pollution. A state-of-the-science water quality model was developed for the system to facilitate contemporary water quality management which includes: 1) development of total phosphorus and ammonia TMDLs and 2) assessing the feasibility of diverting a large point source discharge out of the Lake and into an adjacent river system. The OLWQM consists of a number of submodels representing the major hydrodynamic, water column nutrient cycling, and sediment processes controlling water quality in the lake. The water column submodel describes nitrification, organic matter decomposition, algal photosynthesis, respiration, and nutrient uptake, and zooplankton and zebra mussel grazing and respiration. The sediment flux submodel simulates the conversion of particulate organic material settling from the water column to dissolved nutrients and the concurrent consumption of oxidized compounds from the overlying water column. The model was calibrated over the period from 1994 to 2003 and successfully simulated the major water quality dynamics observed within the system. Additionally, the model simulated the gross patterns in chlorophyll-a in the epilimnion as well as phosphorus retention within the lake sediments. Finally, the model was able to simulate compliance-based measures of important water quality standards and guidance values developed for the lake. The next step of model development includes linkage of the Lake model with a model of the adjacent river system and validation of the linked models.

The response of a small, 32.3 hectare (80 acre), watershed in Harris County to rainfall is simulated entirely hydrologically using the geomorphic instantaneous unit hydrograph (GIUH) methods of Cleveland and others. The simulation is repeated using SWMM 5.0 and only hydraulic elements (entirely hydraulic simulation) for the same watershed, and the same rainfall input. The results are compared to observed rainfall and runoff for the watershed, and produce similar performance. The two simulation approaches are comparable to each other suggesting, among other things, that: 1 A hydrologic model, adequately parameterized captures more than enough hydraulic behavior to estimate watershed response. 2 A hydraulic model for a small watershed is a feasible tool to parameterize a hydrologic model. Such an exercise would be of value when constructing complex integrated hydrologic models, and when incorporating physical changes on the watershed from development, drainage improvements, etc. 3 The GIUH results in this study for this fully developed watershed indicates that the topographic relief and a characteristic velocity reflective of full development captures the essential behavior of the watershed. These findings indicate that hydraulic models can be used to develop a hydrologic responses that are fully traceable in terms of physical characteristics on the watershed, and that the decision to use a hydraulic model or hydrologic model for small watersheds is one of analyst choice, data availability, and project need.

Trichloroethylene (TCE) is one of the most-frequently-detected chemicals in the contaminated groundwater. In the subsurface, TCE can be biodegraded by indigenous microorganisms through coexisting aerobic and anaerobic bioprocesses, which are determined mostly by oxygen, energy sources, and electron acceptors. The bio-processes generate different benign or toxic byproducts. We investigate oxygen transport, induced by the density-driven gas flow and groundwater flow, and the effect of oxygen presence on the fate of TCE and its associated byproducts via the variation of aerobic and anaerobic bioprocesses in the unsaturated and saturated zones. In this study, the types and rates of the bioprocesses depend only on the oxygen-concentration level. Fully coupled nonlinear multiphase flow and multi-species transport equations are formulated and solved using the Galerkin finite element technique. Both sequential dehalogenation and aerobic cometabolic biodegradation of the contaminants are considered. The aerobic bioreaction under oxic conditions had significant impacts on the fate of TCE's byproducts in the subsurface.

A groundwater sample contains a collection of water and solute molecules that entered the aquifer at different times. The distribution of times that the solute molecules entered the aquifer is called a solute age distribution. Assuming ergodicity, a solute age distribution is equivalent to the backward travel time probability density functions (PDF) between the sample location and the land surface. A backward travel time PDF represents the random travel time from an upgradient point of interest (e.g., the land surface) to the sample location, and can be calculated efficiently by solving the adjoint of a forward transport equation. The solute age distribution can be used to assess the potential for future degradation of groundwater quality, and to prioritize remediation activities. We calculate solute age distributions for a stream in Colorado that has been contaminated due to mining activity. We use the solute age distribution to prioritize mine sites for remediation. The highest priority is given to the site whose remediation would lead to the most substantial improvement in the water quality of the stream.

A robust, efficient numerical solution of variably saturated flows in three dimensions will be presented. The solution algorithm was developed by applying the mixed Lagrangian-Eulerian (LE) and Finite Element (FE) approach to Richard's equation. The Lagrangian-Eulerian approach with accurate and robust particle tracking algorithms has been considered a better resolution for sharp front problems. However, the implementation of the algorithm to the advective form of the Richards equation has encountered difficulties resulting from the flux boundary conditions. Therefore, it was decided to develop a mixed LE and FE approach to circumvent the problem. In this approach, LE method was applied to interior nodes and the FE method to incoming-flux-boundary nodes. The goal was to develop numerical tools that can efficiently analyze the flow behaviors in saturated/unsaturated porous media. Application of the hybrid approach to a test problem shows that it is more robust and efficient over the conventional finite element methods.

This paper uses a module of the wellhead protection area model to delineate the zone of capture for five well fields for the city of Enid located in Oklahoma. There are about twenty-five wells in each of the well fields. This model developed by the Environmental Protection Agency is now connected to the Geographical Information System in this research, indicating the zone of capture for the five fields.

The identification of contaminant sources in aquifers is an important issue for the protection of groundwater resources. Recently, various models, including analytical and numerical solutions, have been proposed to solve this problem. In most of these applications the contaminant source identification problem was analyzed using deterministic models. For example, in these applications it was assumed that the aquifer is homogeneous and it has a well-defined hydraulic conductivity distribution. In this study, the parameters such as the hydraulic conductivity and dispersion coefficients are considered to be uncertain parameters. In this study we represent this uncertainty using fuzzy sets. The fuzzy membership functions used in this representation may be based on field data or expert knowledge. Using this approach, the contaminant source identification problem is formulated as an optimization model with fuzzy parameters. The solution is obtained by coupling the genetic algorithm (GA) and vertex method as it is applied to the solution of the optimization model. A hypothetical aquifer is used to demonstrate the effectiveness of the model and the algorithm. The results show that the proposed model can reliably identify the locations of contaminant sources and their release histories for uncertain parameters and the proposed algorithm is shown to be efficient.

There is a growing evidence of that climate change could potentially affect California hydrology and water resource systems. Projections of these climate change conditions imply with high certainty increases in temperature and the associated earlier timing of snowmelt runoff, however projections of changes in precipitation and the associated water available are less certain, some studies showing higher levels of precipitation while others show drier conditions. Is it possible with this knowledge to design adaptation strategies that could be used to mitigate the impacts associated with climate change? And when should these strategies be implemented? Those are some of the questions we answer in a case study of Merced River Basin operations. We approached this problem using an optimization technique known as Sampling Stochastic Dynamic Programming which allows the derivation of reservoir and aquifer operating rules for the considering non-stationary hydrologic conditions such as those associated with climate change. The alternatives we explore follow into three categories: operational changes (changing flood control rules to accommodate earlier timing of inflows); infrastructure changes (increasing storage capacity to accommodate increasingly varying reservoir inflows) and; institutional changes (conjunctive use institutional framework which increases the potential for artificial recharge and a better handling of changing in timing of hydrologic conditions).

A new power plant in south Florida required more than 10,000 gallons per minute (gpm) of reliable groundwater supply for operation. Existing data collected during the design stage indicated poor water quality, especially in the deeper zone of the aquifer. Three production wells were designed, installed and tested on a tight schedule to facilitate plant startup. Each well can yield a minimum of 4,500 gpm. The wells are approximately 1,300 feet in depth and have 24 inch diameter fiberglass reinforced plastic (FRP) inner casings extending from the ground to approximately 1,000 feet below the ground surface. Each well produces groundwater from 23-inch diameter, 300-foot long open holes in the Upper Floridan Aquifer (UFA). Critical design considerations for the wells included adequate groundwater yield, water quality, cost and schedule. The complexity of the well design required onsite supervision by a qualified local hydrogeologist during critical phases and continuous Black & Veatch (B&V) oversight of all activities. A number of unexpected circumstances were encountered during the installation of the wells. This paper discusses the site hydrogeologic, water quality and aquifer yield conditions considered during the well design. The paper also highlights installation difficulties, as well as steps taken to overcome them.

A variable-density groundwater model was developed for the southern half of Florida as part of a regional study to predict the effects of planned aquifer storage and recovery operations. A persistent problem with the model development was that simulated heads in the southern part of the Florida peninsula were consistently less than observed values. Six tests were performed with the numerical model to try and identify the most likely causes of the discrepancy. The tests included explicit representation of (1) permeable fracture zones, (2) regional horizontal anisotropy, (3) low permeability deposits on the ocean floor, (4) disequilibrium from past sea-level stands, (5) increased hydraulic connection through confining units, and (6) the effects of pressure and temperature on fluid density and viscosity. Test results suggest that combining (2) and (6) provides the best match with the observed heads. Future efforts will focus on improving models of the regional flow system.

Protection of drinking water reserves has been the primary concern for governing agencies, environmental stakeholders, and the general populous worldwide. The capability of engineers and planners to incorporate risk assessment in policy-making, offers a valuable tool for implementation of sound policy regarding groundwater protection, while providing an open forum type vehicle to incorporate public inputs in priority setting for protection decisions. This paper illustrates a risk assessment methodology based on prospect theory based on prospect theory systematically analyze alternative recharge zone protection approaches and respective probabilistic impact on groundwater resources, as motivated by recent development over the recharge zone of a sole source aquifer for one of the largest metropolitan areas in the United States. Logical relationships, characterized using fault tree analysis, accurately describe pathways leading from the initial policy decision to final consequences. Comparison of these risk probabilities with limits based on revealed preference concept and prospect theory, affords decision-makers the ability to screen alternatives for acceptability.

In water scarce areas throughout the world, stormwater and wastewater used as an alternative water supply have been put into practice to promote the sustainability of our water infrastructure. Also, in water rich areas, stormwater management and on-site wastewater treatment systems are highly susceptible to extremes in precipitation causing wide spread pollution problems. High nitrogen and phosphorus content in stormwater and wastewater effluents has impeded reuse potential and impacted ecosystem integrity and human health. Nitrate may be toxic and can cause human health problem such as methemoglobinemia, liver damage and even cancers. Phosphorus may trigger the eutrophication issues in fresh water bodies, which could result in toxic algae and endanger the source of drinking waters eventually. It aims to conduct the material characterization and examine the reaction kinetics of a selected recipe of green sorption media recycled from waste streams, such as sawdust and tire crumb, combined with sand/silt and limestone, for nutrient removal using packed bed column tests as a means. Pollutants of concern include ammonia, nitrate and ortho- phosphate. Application potential in stormwater management and wastewater treatment facilities was discussed in the context of sustainable systems engineering.

Although the literature on conjunctive use of surface and groundwater is extensive few papers have analyzed the benefits of coordinating reservoir and aquifer operations. In this work we evaluate reservoir and aquifer operations under three different management schemes. We constructed a monthly non-linear programming model embedded into an annual stochastic dynamic programming model (SDP/NLP model). This model was applied to a case study of the operations of the Merced River Basin, located in the eastern San Joaquin Valley. In a first phase of this application we calibrate the model parameters to match historic operations and the historic level of reservoir-aquifer coordination. We then use the model to estimate the benefits of managing water storage under different institutional and economic scenarios. The scenarios include an electric power scenario (where the reservoir is operated to maximize hydropower benefits), a conjunctive use scenario (where reservoir and aquifer releases are jointed managed to maximize hydropower and agricultural benefits), and a non conjunctive use scenario (where the reservoir is operated independently of groundwater controls).

In this paper, a conflict resolution methodology for conjunctive use of surface and groundwater resources is developed using Nondominated Sorting Genetic Algorithm II (NSGA-II) and the Young conflict resolution theory. The proposed model is applied to the Tehran Aquifer. Annual domestic water consumption in the Tehran metropolitan area is close to one billion cubic meters. The sewer system in this region consists of the traditional absorption wells and domestic waste water pollutes groundwater resources. Some part of the domestic wastewater is drained into local rivers and partially contaminates the surface water resources. This polluted surface water is used in conjunction with groundwater for irrigation purposes in the southern part of the Tehran. Decision makers and stakeholders in the study area have some conflicting interests such as water supply with acceptable quality, reducing the pumping costs, improving the groundwater quality, reducing the construction costs of the Tehran waste water collection system and controlling the groundwater table fluctuations. In the proposed methodology, the MODFLOW and MT3D groundwater quantity and quality simulation models are linked with the NSGA-II optimization model to develop a Pareto front among the objectives. The best point on the Pareto front is then calculated using the Young conflict resolution theory. The results of the proposed model show the significance of applying an integrated approach to surface and groundwater resources in the study area.

Geomatrix has conducted a hydrogeologic assessment of the Inarajan and Tinaga River basins in southern Guam to develop an integrated conceptual hydrologic model of groundwater and surface water interactions in support of potential landfill design and construction. Currently, few hydrologic studies have focused on southern Guam. The model indicates that surface water and groundwater levels are very dynamic in the study area. During below average precipitation years, surface water flow is maintained primarily by groundwater in the dry season and a more balanced contribution of groundwater and precipitation runoff in the rainy season. During above average precipitation years, summer storms interrupt the dry season, resulting in greater surface water flows during the summer months, creating less defined wet and dry seasons. Topography and, to a lesser extent soil type, exhibit the greatest influence on the interactions between surface water and groundwater in the study area. With the onset of the rainy season, headwaters areas for local rivers, exhibiting flatter topography, wetland vegetation, and laterite soils exhibit more rapid rises in groundwater levels than upland areas with more irregular and steeper topography and saprolite soils.

Recent literature articles have highlighted approximation errors inherent in the Domenico analytical solution for describing contaminant fate and transport in groundwater. The Domenico solution is included in two widely-used analytical contaminant fate and transport models—BIOCHLOR and BIOSCREEN. These screening-level models are often used to determine the feasibility of contaminant remediation by monitored natural attenuation. In this paper, the authors compare results obtained from the Domenico solution (BIOCHLOR) to results obtained from another public domain analytical modeling software platform, the analytical contaminant transport analysis system (ACTS). ACTS incorporates an exact analytical solution given by Wexler to quantify contaminant fate and transport in a two-dimensional, infinite aquifer model. The two models are applied in a probabilistic approach for a case study at Oatland Island, Georgia, USA. Because the Wexler approach provides an exact analytical solution, the authors suggest that ACTS provides a more accurate screening analysis tool.

Groundwater remedial design typically requires the development of a reliable mass transport model to evaluate clean up alternatives. A major challenge in the development of a mass transport model is the identification of source release terms such as location and time of release. Although the source location may be characterized during site investigations, the time terms are unknown or poorly known at many sites. This study uses a mass balance-based approach to explicitly account for uncertainty in rectangular pulse release time variables instead of using inverse techniques to rigorously define the release history. The mass balance approach relies on the collection of groundwater concentration data and the standard assumptions used to develop one-dimensional solutions to the advection dispersion equation. A spreadsheet model has been developed to accommodate Monte Carlo simulations, and a concentration dataset from a Nebraska Superfund site was used to evaluate the model. Reasonable results were achieved when the source time parameters were assumed to be random, and the results improved when the mass of contaminant in the aquifer was also assumed to be random.

A preliminary analysis directed towards developing a model for the expected areal-average infiltration into a layered soil profile is presented to represent the random spatial variability of the saturated hydraulic conductivity. The basic framework investigated for the model is the one proposed earlier for vertically homogeneous soils, that should be combined with the model for local infiltration into a two layered soil profile. In this context the possibility of reducing the complexity of a local modelling, which relies on the numerical solution of a system of two ordinary differential equations, is analysed by developing parameterized relations for the time to ponding at the surface and the suction head at the bottom of the upper layer.

During the mid 1990's, the South Carolina Department of Health and Environmental Control (SCDHEC) and the University of South Carolina (USC) entered a joint project to address concerns about groundwater contamination from domestic septic tank systems along the South Carolina coast. Evidence of system failures through the years had been documented in these areas of typically shallow mean groundwater levels. The project employed monitoring wells located along the South Carolina coast and also undertook an extensive modeling effort. The modeling revealed a perceived weakness in the traditional listing order of soils used by many environmental departments in classifying soils for septic tank and absorption field systems (STSAS). This paper will present the case for reordering these soils to better match their failure potential as indicated by the models.

Qanats are renewable water supply systems that have sustained human settlement in arid areas such as Iran. By their very nature, Qanats have encouraged sustainable water use for millennia. However, the socio-economic changes in the 20^th century introduced other water harvesting methods such as deep wells whose immediate advantages caused Qanats to be laid aside even though the application of these new methods alone could not contribute to achieving sustainable water resources. By developing the Causal Loop Diagrams of the problem, this study focuses on the interaction dynamics of Qanats and deep wells to explore the physical and socio-economical reasons of Qanats failure in the 20^th century.

This study conducted in Bongaigaon and Darrang districts of Assam, India is based upon water chemistry and sediment characteristics investigation in an reportedly arsenic infested belt. Of total 50 sampled wells, 15 had arsenic concentration above national drinking water standard of 50 μg/l, and 33 had As concentrations above the WHO guideline of 10 μg/l. However no distinct zones or depths with specific sedimentological features could be identified. Sediments with colour on green-olive scale are probably more likely to bear As contaminated water than white sediments. Sand filters used to reduce high iron content seem to reduce As content of water effectively. Arsenic rich water is also partly avoided since drillers seek water low in iron, which is often also low in arsenic content. Reductive dissolution of Ferric hydroxides is believed to be the release mechanism controlling the mobility of arsenic, rather than oxidation of arsenopyrite or pH induced desorption.

The historical reconstruction process is used to derive contaminant concentrations and exposure levels needed as input by health scientists conducting retrospective epidemiological studies—models are an integral part of this process. However, the models and associated calibrated parameters are inherently uncertain because they are based on limited historical data and information. This gives rise to the question, what is the reliability of the historically reconstructed estimates of contaminant concentrations determined using calibrated models? To answer this question and address the overarching issues of model and parameter variability and uncertainty, a probabilistic analysis is used to generate uncertainties of model inputs (e.g., hydraulic conductivity or contaminant source mass loading rate) so that estimates of uncertainties in model outputs (e.g., water level or contaminant concentrations in groundwater) can be made. In this paper, the authors describe the application of a probabilistic analysis using Monte Carlo simulations to assess model uncertainty and parameter variability. The probabilistic analysis is applied to groundwater-flow and contaminant fate and transport models (MODLFOW and MT3DMS, respectively) as part of an ongoing health study—exposure to volatile organic compounds in drinking water and specific birth defects and childhood cancers—being conducted by the Agency for Toxic Substances and Disease Registry at U.S. Marine Corps Base Camp Lejeune, North Carolina (Figure 1). Results of probabilistic analysis are presented in terms of the probability of occurrence tetrachloroethylene (PCE) contamination in groundwater, the probability of exceeding the current maximum contaminant level for PCE in finished drinking water (5 micrograms per liter), and the range of expected PCE concentrations in finished drinking water during the historical period of interest (1968–1985) for the health study.

The effective saturated hydraulic conductivity is a parameter that relates the average groundwater specific discharge to the average hydraulic gradient. This paper outlines a procedure to calculate the effective saturated hydraulic conductivity in local-scale groundwater flow. Examples are presented in this work.

Measurements of water level, salinity, temperature, and a conservative tracer (Lithium) were obtained from a beach in Prince William Sound (PWS), Alaska. The ultimate goal of the measurements was to evaluate the factors affecting the lingering of oil in the beaches, 17 years after the spill of the Exxon Valdez. The tidal range at the beach was ~4.8 meters, a large value that minimized the effects of salt density gradients. The results were simulated using the code MARUN, a finite element code for density-dependent flow in two-dimensional variably-saturated media. Preliminary calibration of the model revealed that the water level within the beach was greatly dependent on permeability and the freshwater recharge.

Low irrigation efficiencies persist in irrigated areas near Yuma, Arizona due to poorly designed irrigation systems, poor condition of existing systems, inaccurate delivery of flow rates, and inadequate criteria for determining irrigation cutoff to individual basins. In farms where growers lack adequate control over the water supplied to individual basins, conventional irrigation cutoff criteria, based on precise measurement of inflow rates, are ineffective. A joint research project, involving the USDA-ARS-ALARC, University of Arizona, and the USBR, is exploring the management of these systems using the time of advance to half the field length as a criterion for cutoff when inflow rates are not know accurately. Preliminary simulation studies have shown the potential benefits and limitations of such a strategy. This strategy is being tested in the field, to assess its sensitivity to uncertain system properties. This article describes the general research methodology and some of the initial simulation and field results.

US farmers have access to equipment for variable-rate application of most inputs, but some potential benefits of precision agriculture may be masked by uniform application of irrigation water. A system developed at the University of Georgia for variable-rate (VR) water application was installed on a 400-m long center pivot system at the Judd Hill Plantation in northeast Arkansas. The objective of this research is to monitor the system to determine the potential for water and energy savings. A replicated large-plot study was initiated in 2006 based on soil mapping units. Application rates were 13, 19, and 23 mm. No significant cotton yield differences were observed in 2006, probably due to rainfall at the site in July and August. Instrumentation installed in 2007 showed a slightly lower water flow rate and increased water pressure when the end gun was shut off, but the fuel flow rate did not change. The water flow rate decreased during the study period and an additional sensor will be added to test for changes in the water table depth. Future studies are planned to repeat the large-plot study of 2006, monitor the system under a wider range of operating conditions, and investigate possible variable rate nitrogen application through the irrigation system.

Volume balance calculations used in surface irrigation engineering analysis require estimates of surface storage. These calculations are often performed by estimating upstream depth with a normal depth formula. That assumption can result in significant volume estimation errors when upstream flow depth evolves slowly with time and cannot be used under zero-slope conditions. This article examines the errors incurred when calculating upstream depth with an approximation to the zero-inertia equation instead of the normal depth formula. The approximation, which uses an empirical adjustment factor, gives reasonable results under a wide range of hydraulic conditions.

One of the lingering questions in surface irrigation is the relationship between the one-dimensional infiltration associated with borders and basins and the two-dimensional infiltration associated with furrows. A corollary question is the effect of flow variations on furrow infiltration. Definitive answers to these questions would resolve several important evaluation and design issues. For instance, if such relationships were known, a simple field evaluation of a furrow would provide much of the data necessary for border and basin design and management. Or, having this relationship would allow a planner to evaluate the comparative advantages and disadvantages of borders, basins, and furrows within the context of the same system. In 2004 the USDA-NRCS intake families were redefined on the basis of initial furrow irrigations. Later in 2006 the hydraulic properties of these families were determined by parametrically matching HYDRUS 2D (Šimůneck, et al., 1999) simulations to the cumulative infiltration predicted for each family curve. In this paper, the effects of varying wetted perimeter are evaluated in two contexts: (1) how wetted perimeter variations in furrow irrigation can be simulated; and (2) how the two-dimensional furrow intake can be converted to the one-dimensional border or basin cases.

With the expected failure of Landsat 5 within the next five years and the likelihood of no thermal sensor on Landsat 8 scheduled for launch in 2011, the prospect of energy balance determination of evapotranspiration (ET) from Landsat scale resolution (30 m) is dim. An alternative to the computation of a full energy balance is to use the presence of vegetation cover, characterized using a vegetation index, to estimate the relative rate of transpiration from a pixel and then add an additional evaporation amount that stems from a wet soil surface. The wet surface is modeled using precipitation and irrigation amounts and weather data. This approach, while lacking accuracy of the full energy balance, provides means to create ET images using short wave reflectances produced by future medium resolution satellites. The relatively simple evaporation model of FAO-56 is used to compute daily evaporation losses in the context of transpiration from vegetation. These evaporation losses are added to transpiration derived from a vegetation index to produce a complete estimate for ET. Because of the enormous number of pixels in a Landsat scale image (30 million), it is not possible to know specific irrigation timings by field, so that synthetic irrigation events are simulated. Comparisons between synthesized ET from the described approach and ET from a full energy balance computed using METRIC are explored for parts of south central Idaho and error is quantified.

Landsat images are highly preferred to images by MODIS for producing evapotranspiration (ET) maps for specific land use types because of their higher resolution (30 m). However, Landsat images are potentially available only each 16 days, and, with the expected failure of Landsat 5 within the next five years and the likelihood of no thermal sensor on Landsat 8 scheduled for launch in 2011, the prospect of images from Landsat that are useful for application with energy balance determination of evapotranspiration (ET) is dim. Therefore, more use of coarse resolution satellite images, such as 1 km thermal images from MODIS, will occur. One advantage of MODIS satellites is that images having view angle < ~15° are potentially available about each four to five days. Application of METRIC energy balance processes along the Middle Rio Grande of New Mexico using MODIS imagery indicates that one can successfully reproduce monthly and annual ET estimates that were obtained using Landsat imagery. However, spatial fidelity is highly degraded. This paper compares ET images for the Rio Grande region as produced by both MODIS and by Landsat.

In the U.S. Southern High Plains, dairies have expanded and have increased the regional demand for forage and silage. The objectives were to measure water use and determine crop coefficients for corn (Zea mays L.) and forage sorghum (Sorghum bicolor (L.) Moench) produced for silage on the Southern High Plains. Water use was measured with large, precision weighing lysimeters in 2006 and 2007. Both growing seasons had normal to above normal rainfall. The 2006 season was more advective with greater mean daily reference evapotranspiration (ET) rates. Seasonal ET was 671 mm for forage sorghum with a yield of 1.48 kg m^–2 in 2006 and 489 mm in 2007 with a yield of 1.70 kg m^–2; water productivity was 2.21 kg m^–3 in 2006 and 3.47 kg m^–3 in 2007. Seasonal ET was 418 mm for corn for silage with a yield of 1.52 kg m^–2 in 2006 and 671 mm in 2007 with a yield of 2.44 kg m^–2; water productivity was 3.63 kg m^–3 in 2006 and 3.64 kg m^–3 in 2007. Using the 2007 season as a better species comparison, forage sorghum can achieve comparable water productivity as corn with less ET (~73% of corn ET) and irrigation requirement although with a reduced yield (~62% of corn dry matter).

When many places in the world are facing water scarcities, the Devils Lake basin in northeastern North Dakota has received above normal inflow due to excess rainfall since 1993. A research project is being conducted to determine the extent to which irrigation can utilize some of the excess surface waters in the basin without impairing the productivity of soils, many of which are classified as only conditionally irrigable. Understanding of the evapotranspiration (ET) process is critical for irrigation application, but ET research is generally lacking in this region. The sub-humid continental climate in North Dakota has high variations in hourly, daily, seasonal, and annual ET rates. The soil normally stays wet in the early growing season. Irrigation is needed in the mid-growing season when crops are also in a critical stage for supplemental water. In this study, hourly reference evapotranspiration rates for alfalfa were examined by the ASCE EWRI Penman-Monteith method. The weather data used in the calculations were collected from a 42-ha alfalfa field located in Benson County, North Dakota. Thirty minutes values, including air temperature, relative humidity, solar radiation, and wind speed were measured and average hourly values were used in the reference ET calculations. The evaluation and comparison among the daily and sum of 24 hour reference ET provided a good assessment on the highest amount of water that could be potentially used by agricultural crops in the Devils Lake area.

Efficient use of water in agroecosystems requires accurate quantification of evapotranspiration (ET) during growing and non-growing (dormant) periods. Prediction of ET during the growing season has been well researched, but relatively little information exists on evaporative losses during non-growing periods. The objective of this research was to evaluate ET in relation to available energy, precipitation, and reference ET for a corn field during the non-growing period (October 15 through April 30). Three consecutive non-growing periods were studied: 2004–2005 (season I), 2005–2006 (season II), and 2006–2007 (season III). Bowen ratio energy balance system-measured ET was approximately 50% of available energy during average and wet seasons (seasons I and III) and 41% of available energy during a dry season (season II). Cumulative ET ranged from 133 to 167 mm and exceeded precipitation by 21% during the dry season. Mean surface (crop) coefficients were 0.63 and 0.48 for grass and alfalfa-reference crops, respectively. Regression equations were developed that yielded reasonable estimates of ET for the average and wet seasons. Considering non-growing period evaporative losses in water budget calculations would enable water regulatory agencies to better account for water use over the entire year rather than only for the growing season.

The evolving roles and critical priorities of irrigated agriculture, as perceived by practitioners, researchers, and policy makers, were reviewed. Irrigated agriculture has played a vital role in meeting food and fiber demands on a relatively small proportion of total arable land. This role is presently expanding to also include biofuel and industrial materials production. At the same time, water availability is almost universally declining where intensive irrigation has been developed. This has been mainly due to declining water resources, inadequate storage capacity, or greater competition from non-agricultural uses. Although certain priorities may be specific to a location or region, the unifying priorities for irrigated agriculture, in order to meet unprecedented demands by a worldwide population that is increasing both in size and in industrialization, are to increase water productivity, sustain ecosystems, find synergy and avoid conflict among agriculture, urban and environmental uses of water resources.

The Belle Fourche River is a natural stream that drains parts of Butte, Lawrence, and Meade Counties in South Dakota with the headwaters located in Wyoming. The river flows into the Cheyenne River in southern Meade County and ultimately to the Missouri River. The Belle Fourche River Watershed in South Dakota is approximately 2,100,000 acres (3,300 square miles) in size. The Belle Fourche River and Horse Creek, a tributary, are identified in the 1998 and 2002 South Dakota 303(d) Waterbody Lists and the 2004 and 2006 Integrated Report for Surface Water Quality Assessment as impaired because of elevated total suspended solids (TSS). A TSS Total Maximum Daily Load (TMDL) was approved by the Environmental Protection Agency in 2003 for both streams. The Belle Fourche Irrigation District (BFID), identified in the TMDL as a significant contributor to TSS loading, delivers water to 57,183 acres of farmland through its 94 miles of open main channel and 450 miles of open lateral ditches. This paper will discuss the complete water management system that was developed for the BFID. This system was designed to reduce the amount of sediment-laden flows entering the streams by increasing the overall delivery efficiency of the BFID. The components of this management system include automated check structures, head gates, and flow-measuring devices along the main canals and laterals; software to automate the water order and billing system; water master software to calculate a water mass balance needed to support water orders and compare to actual measurements; software to automate the water order and billing system; and Web-based irrigation scheduling software. Many of the automated structures are connected via radio network to the BFID headquarters, which allows personnel to monitor and control settings in real-time. Before the development of the complete water management system, the BFID operated the canals manually and performed all calculations to determine water orders, water billing, and water mass balance by hand. This was extremely labor-intensive and led to inefficiencies in the transport of the water from the dam to the farmer's fields. The new water management system provides timely information to support the decision-making process. The system allows BFID personnel to assess and manage the entire system to better offset fluctuations in deliveries caused by rainfall, heat, or equipment malfunctions while substantially reducing the amount of time and effort required to perform their daily tasks.

An economic optimization model for a sixty years planning horizon is developed using available groundwater resources in the Texas County of Oklahoma Panhandle. Net present value and total water use over 60 years is used to estimate the value of water for irrigated agriculture in the area. The model will serve as a policy tool to analyze alternative water management strategies and water conservation programs that can possibly be implemented in the area. The results from the model will also be used to assess the economic impact of depleting groundwater availability from the Ogallala Aquifer. The economic optimization model can be used to analyze alternative policy scenarios such as change in corn prices due to ethanol production, water pumping restriction and incentives to producers for management practices to be used for water conservation.

Water use in the West is changing, and nowhere is that being felt as acutely as the Imperial Irrigation District, a 450,000-acre, 12-month growing season district in Southern California where longstanding agricultural water users are under intense pressure to transfer water to the region's ever-thirsty and ever-expanding urban areas. In 2003, the District entered into 37 transfer agreements (IID, 2007), referred to collectively as the Quantification Settlement (QSA) and related agreements. The QSA committed the District to a massive efficiency conservation program that would free up roughly 10 percent of its water for transfer to San Diego and others. The heart of the QSA calls for the District to generate more than 300,000 acre-feet of water through a combination of District and voluntary on-farm efficiency conservation savings. In 2007, IID completed their Efficiency Conservation Definite Plan (Definite Plan) that outlined strategies for both delivery system and on-farm water savings. The pertinent terms of the water transfer agreements and their implication to development of the Definite Plan are discussed and the elements of the Definite Plan are presented. The paper concludes with an assessment of lessons learned and discussion of key technical and other issues encountered.

Solar radiation data are critically important for the estimation of evapotranspiration. Analysis of visible-channel data derived from Geostationary Operational Environmental Satellites (GOES) using radiative transfer modeling has been used to produce spatially- and temporally-distributed datasets of solar radiation. An extensive network of (pyranometer) surface measurements of solar radiation in the State of Florida has allowed refined calibration of a GOES-derived daily integrated radiation data product. This refinement of radiation data allowed for corrections of satellite sensor drift, satellite generational change, and consideration of the highly-variable cloudy conditions that are typical of Florida. To aid in calibration of a GOES-derived radiation product, solar radiation data for the period 1995–2004 from 58 field stations that are located throughout the State were compiled. The GOES radiation product was calibrated by way of a three-step process: 1) comparison with ground-based pyranometer measurements on clear reference days, 2) correcting for a bias related to cloud cover, and 3) deriving month-by-month bias correction factors. Pre-calibration results indicated good model performance, with a station-averaged model error of 2.2 MJ m^–2 day^–1 (13 percent). Calibration reduced errors to 1.7 MJ m^–2 day^–1 (10 percent) and also removed time- and cloudiness-related biases. The final dataset has been used to produce Statewide evapotranspiration estimates.

SEBAL (Surface Energy Balance Algorithm for Land), a spatial evapotranspiration (ET) estimation method, has been applied with Landsat Thematic Mapper (TM) data throughout the world. However, it has never been tested for semiarid conditions of the Texas High Plains. In this study, SEBAL algorithm was applied to a Landsat TM image acquired on July 10, 2007 covering a major portion of the Texas High Plains. Performance of SEBAL was evaluated by comparing estimated ET with measured ET data on four large monolithic lysimeters at the USDA-ARS Conservation and Production Research Laboratory, Bushland, TX. Comparison of SEBAL-estimated instantaneous ET values with lysimetric measurements indicated that SEBAL may provide better ET estimates for irrigated fields. However, it performed poorly in predicting ET for fields under dryland management. This result may indicate that SEBAL might be sensitive to errors in the selection of the hot/dry pixel. Overall, SEBAL is a promising tool for mapping ET in the extensively irrigated Texas High Plains. However, more evaluation is needed for different agroclimatological conditions in the region.

It is important to quantify the consumptive water use by the vegetation when managing regional water resources in irrigated areas. Suitable models and algorithms applied to high resolution (30 m) satellite imagery provide a cost effective and time efficient method to obtain evapotranspiration estimations from bare soil and vegetation. The METRIC image processing model calculates net radiation, soil heat flux and sensible heat flux through a number of steps before estimating evapotranspiration as the residual from the energy balance. Sensible heat flux algorithms are calibrated using an operator selected wet and dry pixel. The complete energy balance obtained from the satellite images is calibrated using ground based reference evapotranspiration estimations. The paper describes an application of the METRIC model on parts of the South Platte and North Platte rivers in Colorado and Nebraska for individual days in 1997, 2001 and 2002. Landsat 5 and Landsat 7 shortwave and longwave bands were used. Weather data from selected meteorological stations within the study area was screened and used to estimate reference evapotranspiration. A water balance model was used to estimate evaporation from the soil. During the image processing it was necessary to iterate the selection of the wet and dry pixels after reviewing evapotranspiration behavior for natural vegetation and wet fields at full cover. Uneven distribution of recent precipitation events and operator dependency needed to be addressed. The resulting evapotranspiration maps appear to be congruent with ET from previous studies and will be used by local water management entities.

Evapotranspiration (ET) is the major consumptive use of irrigation water, and thus, spatial and temporal quantification of ET is important to agricultural water management. In water rights management and precision irrigation, information on ET is desirable on a field or subfield scale. Therefore, fine resolution satellite imagery and ET products derived from the satellite imagery are highly desirable. However, for a majority of satellites, spatial resolution of the longwave (thermal) band(s) is coarser than the coincident shortwave bands, which creates a compatibility and correspondence issue for the data used for energy balance (EB) and increases the net pixel resolution and reduces fidelity of ET calculations. Typically, surface temperature (T_s) and vegetation indices (VI) are closely correlated, especially under conditions of high availability of soil water, due to the effects of evaporative cooling by vegetation, especially some days after wetting events, when the exposed soil surface is dry and warm relative to vegetation. This physical relationship can be exploited to sharpen T_s using VI if the assumption of cooled surface by vegetation holds. This paper describes a technique developed for application with the METRIC and SEBAL EB procedures that uses the concept of hot and cold thermal conditions associated with dry and wet surface conditions during calibration as a means to distribute T_s at a subpixel scale using subpixel VI. The result is an image of T_s that has the same spatial resolution of the short wave images. Therefore, the resolution of ET images created during the METRIC or SEBAL processes can have equally high resolution. Applications made in Idaho and New Mexico using sharpened thermal imagery are described.

Recent drought events in the U.S. have threatened drinking water supplies for communities in Maryland and Chesapeake Bay in 2001 through September 2002, Lake Mead in Las Vegas in 2000 through 2004, the Peace River and Lake Okeechobee in South Florida in 2006, and Lake Lanier in Atlanta, Georgia in 2007. In the environmental science community, there is a renewed interest to develop a new "Water Availability Index (WAI)" that serves for short-term water resources planning and water infrastructure management in dry periods. Such a development may be geared toward presenting a near real-time, risk informed and forward-looking instrumental message in terms of both the quantity and quality of available fresh water in major metropolitan regions. The success of this effort could incorporate the use of integrated remote sensing technologies in concert with intermediate- and long-term climate change forecasts. It is the aim of this paper to present a state-of-the-art review about: 1) How the multi-scale and multi-dimensional databases are collected by optical and microwave satellite images, such as the NASA GOES, MODIS Terra and Aqua etc., and ground-based radar stations, such as the NOAA NEXRAD system, and 2) How these databases can be applied to support the development of a new WAI and help reduce the managerial risks of water infrastructure across the continental U.S. These discussions lead to the derivation of a new WAI with the aid of remote sensing technology.

In the Western part of the United States of America, more and more irrigation canal networks are being modernized, which often includes some form of real-time automatic water level control. This real-time control consists of water level measurements that are communicated to a controller. The controller calculates the required control actions and communicates these back to the adjustable gates. The objective of the controller is to maintain the water levels in the canal pools at a given target level. The control loop is repeated at a fixed time interval. To attenuate noise and undesired signal contents, filtering of the water level measurements is required. The reasons that irrigation districts decide to automate their canals include: improved water delivery service, improved efficiency of water delivery, improved utilization of labor, and water resource stewardship. The design of a water level controller is not obvious. On one hand, the reaction to flow disturbances or changes in target level should be fast. On the other hand, tuning the controller to react too strongly to these disturbances can result in overreaction and water levels that severely oscillate. Research on control of open channels has resulted in design (tuning) rules for water level control and filtering that are based on estimates of certain pool characteristics. These characteristics are the storage area of the back water part of the pool, the delay time from upstream side to downstream end and for short, flat and deep pools the frequency and peak magnitude of the basic reflecting wave (resonance) as well. This article presents a procedure to determine the pool characteristics required for controller and filter design. The procedure applies system identification tools and was tested on several canal pools at the Central Arizona Irrigation and Drainage District, Eloy, AZ. The identification procedure results in realistic characteristics for the pools.

Irrigation canals are often designed for water transmission. The design engineer simply ensures that the canal will pass the maximum design discharge. However, irrigation canals frequently operated far below design capacity. Because demands, and therefore the distribution of flow at bifurcations (branch points), can vary from day to day, or even from hour to hour, to meet user demands, the hydraulic grade line of the canal can vary significantly over the range of flows encountered. This complicates the operator's job of distributing flow to users. Common problems include; insufficient head at low flows for turnouts in the upper end of pools, gates that transition from free to submerged flow over the range of conditions, culverts that greatly change the pool volume over the range of discharges due to backwater effects, canal gates that are oversized for safety which limits small discharge changes, variable backwater conditions that compromise flow measurement devices (both in pipes and channels), incompatible hardware for automated control of check gates, etc. Examples from canal systems in Central Arizona are given with options for improving operations. This quote from an irrigation district engineer says it best "Design engineers should be forced to operate the canal systems that they design."

Polyacrylamides (PAMs) have been historically used in industrial and environmental settings in food packaging, paper manufacturing, waste water treatment, and soil loss prevention. Recently, PAM has been considered for use in unlined earthen irrigation canals to reduce seepage losses. To evaluate the potential benefits and risks associated with PAM applications to irrigation canals, a series of studies have been conducted by the Desert Research Institute (DRI) in collaboration with the US Bureau of Reclamation (USBR). The purpose of this research was to investigate the impacts of shear stress on soil hydraulic conductivity of a PAM treated soil. A small experimental flume was built to accommodate four soil columns attached to its bed. The soil columns were filled with engineered sand and treated with three PAM concentrations and a control (no PAM). Water flux and K_sat were measured through the soil columns over a period of several hours. Experiments were completed for three flowrates and a control (no flow). Four major conclusions were drawn from the experimental results: 1) a reduction in water flux was observed as a function of PAM concentration; 2) when the PAM application was free of imperfections, the PAM layer was resistant to shearing; 3) imperfections in the PAM layer (e.g. bubbles or rips) caused a substantial increase in water flux; and 4) failure of the PAM layer occurred abruptly and was highly variable, although typically associated with a flaws in the PAM layer.

Many irrigation districts use Supervisory Control and Data Acquisition (SCADA) software to manage their canal systems. Whether homegrown or commercial, these programs require a significant amount of training for new operators. While some SCADA operators are hired with extensive field experience, others are hired with no field experience at all and require extended training to gain an understanding of the behavior of open-channel systems. Regardless of their experience, these operators usually receive SCADA training while managing the actual canal system and thus their training is driven by the day-to-day operation of the system. The SCADA operators receive no hands-on training for emergency situations such as hardware vandalism, large storm events, or a canal breach. Creating these emergency situations in a canal system for training purposes leads to wasting water, causing significant fluctuations in water levels in the adjoining pools, or potentially causing severe damage to the canal system. Recently, researchers at the U.S. Arid Land Agricultural Research Center created a training tool that replaces the real canal with a hydraulic simulation model without making any changes to the SCADA software. Employees at WEST Consultants, Inc. recently modified this training tool so that it works with HEC-RAS as the hydraulic simulation model. Using this system, SCADA operators can be trained to operate a canal system under a wide range of emergency situations without endangering the actual canal system or wasting water. This type of training should reduce the time required to train operators, allow the SCADA operators to route flow changes more efficiently through the system, and give operators a larger knowledge base with which to handle emergency situations. This training tool was recently applied to the Central Arizona Irrigation and Drainage District in Eloy, Arizona. Because of the flexibility and applicability of this training tool, we hope that this tool can be used in a wide range of training situations.

This paper deals with errors in estimation of soil water depletion inirrigation management. Such errors can reduce net economic returns to water, increase economic risk and motivate risk averse farm managers to adopt less profitable strategies. Two common methods of estimating depletion are discussed, one based on cumulative ET the other on soil moisture measurements. Both are characterized by significant uncertainty. It is common practice to rely on one or the other of these estimators for irrigation scheduling. This paper proposes an alternative approach that utilizes both estimators in combination. Rather than treating them as deterministic quantities, they are treated as random variables. The probability distributions of each are combined in a Bayesian analysis to derive a probability distribution of depletion, which then provides a better basis for irrigation decisions.

Revised irrigation demands are calculated for the 21 northernmost counties in Texas, identified as Region A, using the TAMA (Texas A&M—Amarillo) agricultural water use demand estimation model. Year 2000 demands are presented using the existing mixture of crops, average evapotranspiration values and actual irrigation application practice values. Current demand values are expected to exceed the allowable water supply in several, intensively irrigated counties within the region. Thus, the alternative, lower water use crop of cotton is evaluated in terms of substitution potential for the presently produced, more intensive water use crop of corn. Although cotton has significant, differing production requirements in northern Texas, successful production has been documented within the region at the North Plains Research Field (NPRF) and average yield parameters are presented. The water savings impact of converting percentages of county acreages from corn to cotton is reported and discussed. The water conservation impact to the Ogallala aquifer is calculated over the region's current 60-year planning horizon. The potential impact of recent ethanol demands is briefly discussed.

A field study was conducted near Garden City, Kansas to measure corn grain yield response to a range of rates from full to deficit irrigation. The contributions of antecedent stored soil water to crop water use were determined from soil water measurements near the beginning and the end of the growing season. Above average winter precipitation contributed to pre-plant soil water accumulations and deficit irrigation caused more growing season stored soil water use. Field results were compared with the Crop Water Yield (CWY) predictions of field results. Correlation of relative yields from field results and the CWY simulation were good, showing that the CWY has potential to be used as a management tool to screen potential irrigation scheduling scenarios for deficit irrigation.

Most of the agriculture in the Great Plains and western U.S. is water-limited, consisting of rain-fed, dry-land, cropping systems or range-livestock systems and some irrigated cropping systems where irrigation water is available. Prolonged drought in the last few years has aggravated the situation, and greater frequency of severe droughts predicted by global climate change models is a cause for great concern, especially for dry-land systems. At the same time, the increasing water demands for drinking, sanitation, urban irrigation, industry, and environmental uses are outbidding and reducing the irrigation water available for agriculture. Similar situation exists in many other arid to semi-arid parts of the world. To obtain maximum return out of limited rainfall and irrigation water, with minimum environmental impact, the producers need whole-system and quantitative management tools to help them optimize the use of available water and minimize associated inputs on site-specific and field-specific basis. The tools should help determine appropriate crop sequences, and optimize the use of limited rainfall and irrigation water with respect to the amounts and timings of rainfall, critical growth stages of crop, soil fertility, and weather conditions; help determine an optimal selection of alternate crops during droughts; and an optimal allocation of limited water among crops. There is currently great excitement about growing bio-energy crops in the area, including the dry-land oil seed crops and irrigated corn or other biomass crops. The above tools should also be able to evaluate the long-term economics of bio-energy crops while leaving enough crop residues on the soil to maintain soil organic matter.

The performance of the agricultural sector in the Texas Panhandle is dependent on irrigation. The declining availability of irrigation water from the Ogallala aquifer combined with increasing energy costs make irrigation strategies much more critical. Economic viability and resource conservation are not mutually exclusive. Selecting an irrigation level maximizes profits both increases profits and conserves the water resource as compared with a strategies of maximizing yield per acre. Under average precipitation, a management strategy that irrigates to maximize yield reduces profit by between $22 and $158 per acre and increases water consumption by 2.21 and 11.20 acre inches depending on the combination of corn and natural gas prices. Adopting a profit maximizing strategy is a win-win situation both economically and for water resource conversation.

In Japan, the "Law on promoting proper management and use of livestock excreta" (animal waste regulations) was implemented nationwide in November 2004; this law prohibited the disposal of animal wastes in earthen storage ponds. To examine the effects of this law, a 2-year daily analysis of water quality and hydrology of a drainage canal of an agricultural area with intensive livestock production in the Lake Kasumigaura Basin, Japan, was conducted from November 2003 to October 2005. The water quality indices were total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus, and chemical oxygen demand. Considering daily precipitations during the irrigation and non-irrigation periods, both the concentrations of pollutants and effluent loads were compared between the prelaw and postlaw periods. The results suggested that the amount of effluent loads from animal wastes to drainage decreased after the enforcement of this law and that animal waste regulations were among the most effective local adaptation strategies for reducing effluent loads from agricultural areas.

We paid attention to relationship between farming activities and changes in drainage water quality from a paddy fields area, especially in land preparation period for transplanting of paddy. Drainage water quality during land preparation period became highest concentration of all items through a year. In 2006, average water qualities in the period were 7.9 mg/L in T-N, 1.6 mg/L in T-P, 15.3 mg/L in TOC, and 372 mg/L in SS. In addition, maximum values in the period were 36.2 mg/L in T-N, 12.3 mg/L in T-P, 83.2 mg/L in TOC, and 3020 mg/L in SS. The changes in water quality moved on with land preparation by tractor and drainage gate operation on each paddy field by farmers. Moreover, relatively high concentrations of drainage water were also observed during non-irrigation period. As no agricultural activities were done during the period, it is considered that residual nutrient in soil will infiltrate by rain water and flow to the drainage channel.

Soil erosion and runoff have led to agricultural and environmental problems throughout the world. Therefore effective measures which can reduce sediment yield in the farmland are necessary. For the purpose, advanced sediment management technique is required. A study area is Nagura-river watershed, Ishigaki Island, Japan. GIS for sediment management in watershed was constructed. Consequently, multi-points observation was carried out at six points in the watershed. In these studies, a soil erosion and sediment runoff model was constructed and tested to verify their applicability in predicting sediment yield and sediment runoff. The calculated sediment runoff by the model was in approximate agreement with the observed. In the present application to the watershed sediment management, the authors carried out some case studies to choose proper combination of sediment yield reduction measures. The calculation has shown that sediment runoff at outlet of the watershed can be reduced by 12% if the measures about land deformation are taken into consideration. Another calculation has shown that sediment runoff can be reduced by 74% if the combination of measures about land deformation and about farming program is properly chosen.

Surface energy fluxes, including sensible heat, latent heat, net radiation, and soil heat flux, play crucial role in surface energy dynamics of any terrain or landscapes. Estimation or measurement of these energy fluxes is critical for completing the water balance in terrestrial ecosystems, and therefore accurately predicting the effects of global climate and land use change. There are various methods available for ET estimation. Bowen ratio energy balance and eddy correlation techniques offer powerful alternatives for measuring land surface energy fluxes. In spite of the elegance, high accuracy and theoretical attractions of these techniques for measuring ET, their practical use over large areas can be limited. These techniques provide measurements at a point scale and may not be practical when quantifying water use over large areas due to the number of measurement sites needed and the operational expense of such a dense network. Application of ET mapping from satellite measurements can overcome aforementioned limitations. The objective of this study is to assess the performance of the METRIC^TM (Mapping Evapotranspiration at high Resolution using Internalized Calibration) model for estimating land surface energy fluxes to improve our understanding of processes that govern water use in managed and native ecosystems in south-central Nebraska.

Proper irrigation management is critical when using poor quality water such as reuse water on golf courses in the arid southwestern United States. Results from multiple studies conducted by this author are reviewed and reported on in this paper. A survey of golf course superintendent's attitudes and perceptions toward using reuse water revealed little opposition to using reuse water but a realization that using reuse water can negatively impact golf course operations. Key irrigation management factors are discussed that can significantly alter the ability of a superintendent to maintain a healthy productive turfgrass stand when using reuse water. The quality of reuse water varies from region to region and superintendents need to have real time water quality analysis to successfully maintain favorable water, nutrient and salt balances. Golfcourses also contain a significant amount of trees, shrubs and flowering annuals in which care must be taken to minimize foliar application of reuse water. Because in the future golfcourses in the arid southwest may face the challenge of being forced to deficit irrigate with reuse water, it is critical that the golf course industry be proactive toward this challenge. It is this author's opinion that golfcourses need to shift toward precision agriculture. This will require not only using weather based and soil based information but also cutting edge technology based on remote sensing.

Salt accumulation in soils of arid areas is usually attributed to the quality of irrigation water, soil characteristics, type of irrigation system, and the current irrigation practices. The buildup of salts in the root zones can adversely impact the crop production. The addition of chemicals to crops is a common cause of groundwater contamination as chemicals are usually applied in conjunction with irrigation. Over application of irrigation water can transport chemicals into underlying aquifers and render them unfit for human consumption. In United Arab Emirates "UAE", most of the irrigation water is applied using drip irrigation systems. This study presents the experimental results of electro-kinetic method applied to manage the nitrate migration under variable saturation conditions in sandy soil representative of the UAE conditions. The nitrate is considered here as a representative of the nitrogen existing in the utilized fertilizers. A number of experiments were conducted evaluating the system performance subjected to different conditions. These included level of soil compaction, soil washing, and levels of applied currents. The results show that the electro-kinetic process was efficient in retaining and concentrating the soil nitrate near the anode. Observations and analyses of the results are discussed to better understand the salts electro-migration under the impact of investigated conditions.

The Penman-Monteith model (PM) is a useful "one-step" method for evapotranspiration (ET) estimation, if surface resistance (r_s-ms^–1) estimates can be derived. This study has as its objective to evaluate different methods of r_s estimation and the accuracy of the resulting ET estimates in common bean (P. vulgaris L.). The experiment was conducted at the Fortuna Agricultural Experiment Station at Juana Diaz, PR. Four automated weather stations were placed in plots planted with two genotypes of common bean (Phaseolus vulgaris L.). Net radiation, soil heat flux, soil temperature, soil moisture, air temperature, relative humidity, wind speed and direction were recorded at ten second intervals. Each weather station had an elevator system that moved the air temperature and relative humidity sensor between two vertical positions over the crop canopy every two minutes during a complete day. The r_s was derived by stomatal resistance (r_L) and leaf area index (LAI) measurements (PM-1), and by direct micrometeorological variables as follows: inverse of the general PM-model (PM-2), as a function of the soil moisture (PM-3), and as a latent heat flux-λE (PM-4 and ET-Station). The results indicate that PM-1 under-estimated r_s at low LAI, and that r_s and r_L are influenced inversely by the aerodynamic resistance (r_a), which affected the precision of the PM-2 and ET station estimation especially under windy and dry conditions, but not the PM-3 and PM-4 methods.

The two-layer model of Shuttlerworth and Wallace (SW) was evaluated to estimate vine transpirationa (T_sw) and soil evaporation (E_sw) from a drip-irrigated Merlot vineyard, located in the Talca Valley, Region del Maule, Chile (35° 25' LS; 71° 32' LW; 136m above the sea level). An automatic weather system was installed in the center of the vineyard to measure air temperature, relative humidity, wind speed, solar radiation and latent heat flux during January 2007. Values of T_sw and E_sw were compared to sap flow and microlysimeter measurements, respectively. Also, vineyard evapotranspiration (ET_sw) computed by the SW model was evaluated using latent heat flux measurements obtained from an eddy-covariance system on a 30 minute time interval. Results indicated that SW model was able to predict vineyard evapotranspiration with a root mean square error (RMSE) of 0.3 mm day^–1. Also, SW model predicted soil evaporation and vine transpiration with RMSE of 0.2 and 0.8 mm day^–1, respectively. In general, the SW model tended to underestimate transpiration and vineyard evapotranspiration, and overestimate the soil evaporation.

A study was initiated in Fall 2006 in Raleigh, North Carolina to compare two types of commercially available irrigation control technologies, one based on estimates of evapotranspiration (ET) and the other based on feedback from soil moisture sensors. Water applied and turf quality from one ET-based system and two sensor-based systems were compared to a system using a standard time-based irrigation schedule. The effect of irrigation frequency was also a part of the study. Estimates of turf ET were obtained from the Penman-Monteith equation using on-site weather data, and also from an atmometer. Results from the twenty week evaluation in 2007 showed that on average the "add-on" soil-moisture-based system evaluated applied the least amount of water while the ET-based system evaluated applied the most water. Weekly irrigation frequencies used the least amount of water, followed by bi-weekly and daily frequencies in increasing amounts when averaged across all technologies. Minimally acceptable turf quality was maintained by all technologies and frequencies through most of the study, but turf quality declined substantially the last month of the study for the add-on system and standard timer-based system. The "on-demand" sensor-based system resulted in the best combination of water efficiency and turf quality.

Heavy rains caused the discharge of 48 million gallons of raw sewage into the Ala Wai Canal. This canal discharges out to sea near popular beaches. The Department of Health closed the nearby beaches (Waikiki, Magic Island, Ala Moana) based on the C. perfringens state water quality standard rather than the enterococci U.S. Environmental Protection Agency standard. This caused the public to be confused and distrustful. The University of Hawaii monitored the same beach sites for more sewage specific microorganisms (F+ coliphages by culture, human specific Bacteroides by PCR). The results showed that the beaches were contaminated with sewage two days after the sewage spill ended but had been cleared by the fourth day. These results supported the Department of Health's decision of opening the beaches six days after the end of the sewage spill. The heavy rains that caused the sewage spill also diluted and transported the sewage out of the canal and out to sea.

According to United Nations (UN) data, over one billion people lack access to domestic water supply and 2.4 billion people lack elementary sanitation. The World Health Organization (WHO) estimates that by the year 2020, the number of people without access to water services will increase from 300 million (in 2003) to 400 million. In addition, by 2030, more than 50% of the population on the African continent will live in urban areas thereby increasing the demand on already stressed water resources. This paper describes how rainfall harvesting could be implemented to improve the availability of water in certain parts of West Africa. The implementation of rainfall harvesting strategies could result in very effective and sustainable water supply alternatives in the regions considered. The methods described focus on the implementation of solutions particularly tailored for the region. While most rainfall harvesting schemes focus on domestic rainfall harvesting (DRH) and thus water supply alternatives for residential use, this paper additionally explores water supply alternatives that could serve small communities like schools and small business centers. A brief discussion of Living Machines (LMs) is provided to motivate the presentation of larger-scale integrated rainfall harvesting and water recycling methods. The function and the basic principles underlying the development of LMs are included. The goal is to examine adaptations of LMs in the development of larger scale water systems that include rainfall harvesting and water recycling.

A systematic temporal and spatial analysis is being conducted at the U.S. EPA on historical precipitation and stream flow in the Lower Mississippi River basin (LMRB) and their relationships with Atlantic hurricanes and flooding events. The objectives are to decipher the periodicity and long-term trends exhibited in the hydroclimatic regime, and to determine their implications on the security of community water supplies in the region and the Gulf Coast, the parts of the continental U.S. prone to the negative impacts of extreme weather events under the current and future climate conditions. Statistical modeling using wavelet functions shows periodicity of continental precipitation and hurricanes with characteristic changes of trends around 1890–1900, 1940–1960, and the 1990s. These long-term decadal and multi-decadal changes were identified in a spatial modeling and wavelet frequency analysis of the 24-hour daily precipitation data obtained from the National Climatic Data Center. Long-term variations are also detected in hurricane and flooding events. Based on these findings, one can incorporate the hydroclimatic periodicity and long-term variations into the emergency water supply management and system designs. Measures such as water intake protection, using decentralized water supply, and planning emergency management are potential options in natural disaster preparedness. The results of the first phase investigation are discussed.

Traditional technologies exist to address wet weather overflows but are many times cost prohibitive, can yield toxic by-products and in areas of older infrastructure, space for facilities to treat overflows is often limited if available at all. As such more cost effective technologies, requiring less space and producing less harmful by-products are currently being explored. One such possibility for alternative high-rate disinfection has been investigated using hydrogen peroxide in conjunction with a catalyst to speed up the oxidative reaction. Given that the only by-products of the reaction with hydrogen peroxide are water and oxygen, a reaction with a short contact time and high kill rate can prove not only valuable where space is limited, but is also extremely environmentally sound.

The presence of nanoparticles in drinking water sources could impact organic pollutant removal by activated carbon due to agglomerated nanoparticles, which could act as adsorption sites for pollutants. Trichloroethylene (TCE) adsorption onto activated carbon in the presence of nanoparticles was evaluated in this study. Iron oxide (Fe₂O₃), titanium dioxide (TiO₂), and silicon dioxide (SiO₂) nanoparticles at two concentration levels (0.5 and 1.0 mg/L for Fe₂O₃ and TiO₂, and 5.0 and 10 mg/L for SiO₂) were evaluated. Particle size distribution (PSD) of the above nanoparticle solutions was analyzed in order to determine the extent of aggregation. Adsorption isotherm experiments were conducted at three initial TCE concentrations, two nanoparticle concentrations, and with varying amounts of powdered activated carbon (PAC). Isotherm experiments were also conducted in the presence of natural organic matter (NOM) in order to more closely model natural water conditions. The primary objective of this study is to evaluate the efficacy of activated carbon adsorption of TCE in the presence of the aforementioned commercially available nanomaterials and NOM.

In many suburban areas in the United States, innovative onsite wastewater treatment technologies are often the most cost-effective solution when poor soil conditions exist. In many situations, the use of aerobic treatment units with drip or spray effluent dispersement is the most cost effective onsite wastewater treatment solution. Although the science and engineering of this system concept is well-established, the interpretation of this science, as embodied in state and local codes, varies significantly. The consequences of these variations in code result in suburban areas where development is flourishing while in other suburban areas development is limited. This paper compares state onsite waste water code regulations for North Carolina, Texas, Virginia, Tennessee, and Pennsylvania.

The South Florida Water Management District (District) is responsible for managing water resources in 16-counties over a 46,439-square kilometer (17,930 square-mile) area. The District's area extends from Orlando to Key West and from the Gulf of Mexico to the Atlantic Ocean and contains the country's second largest freshwater lake, Lake Okeechobee, and the world-famous Everglades wetlands. The District manages water in one of the most diverse and complex ecosystems in the world — the interconnected Kissimmee-Okeechobee-Everglades system. The District's routine work includes buying and managing land, restoring floodplains, revitalizing shoreline habitats, and protecting wetlands. The District's mission is to provide regional flood control, water supply, and water quality protection as well as ecosystem restoration. During last ten years, the District has constructed and operates six Stormwater Treatment Areas that are large constructed wetlands to reduce the nutrients in water. Specially, six Stormwater Treatment Areas are designed to reduce the level of phosphorus entering the Everglades. Stormwater Treatment Area 2 (STA-2) is located in southern Palm Beach County and captures stormwater runoff originating from the S-6 watershed, upstream of the S-6 pump station. The STA is populated with sawgrass and cattail to reduce phosphorus levels, before it is released into Water Conservation Area 2A. STA-2 has many water control structures including pumps and gated culverts and spillways. These water control structures have complex hydraulic conditions that require a set of complex physics-based flow estimating equations. The Artificial Neural Network (ANN) models were developed, tested and validated for flow estimation purpose at the water control structures. Their application in estimating flow and missing tail water elevations at water control structures culverts G331 and G333, and spillway G332 were successfully demonstrated in a case study.

An optimal control model (OCM) is developed by coupling a semi-distributed hydrological model, Soil and Water Assessment Tool (SWAT), with a genetic algorithm (GA) to identify the least cost design (sizes, types, and locations) of structural best management practices (BMPs) while meeting treatment goals at a watershed-scale. Treatment goals considered are constraints on daily peak flow values and annual sediment load. SWAT performs the hydrological simulation incorporating combinations of BMPs while the GA searches for the least cost combination. Structural BMPs included in the OCM include detention ponds, infiltration ponds, parallel terraces, filter strips, grade stabilization structures, and grassed waterways. The model is demonstrated on Silver Creek watershed, a sub-watershed of the Lower Kaskaskia basin in Illinois. The OCM is able to find optimal or near optimal solutions for different scenarios of treatment goals.

Handling constraints in Evolutionary Algorithms (EAs) can be a challenging issue. Because constraints are not handled directly, heuristics must be carefully designed and applied to guide the search toward feasible and good-performing solutions. Penalty functions are the most commonly used method to handle constraints in EAs. There are many possible formulations for penalty functions. One drawback of penalty functions is that they require time-consuming fine-tuning of the penalty parameters to effectively search for feasible solutions with good objective function values. Alternative techniques have also been reported in the literature, including multi-objective optimization techniques, which treat the constraints in single objective problems as additional objectives. In this paper, various constraint-handling techniques are applied to an EA-based watershed management problem to investigate their performance and sensitivity to fine-tuning parameters. The watershed management problem involves designing detention ponds in a system-wide manner in conjunction with land use allocation to provide a desired level of long-term system-wide pollutant removal at the least cost. The constraint-handling methods investigated include several penalty functions and alternative constraint-handling techniques. The associated fine-tuning parameters for each constraint-handling method are varied to investigate the sensitivity of the solution quality (feasibility and objective function value) to these parameters. The solution quality and its sensitivity to the constraint-handling parameters are compared. This comparison is intended to help provide guidelines for better-performing constraint-handling methods for a watershed management problem that can be successfully implemented without excessive fine-tuning requirements.

The first part of a two-step decision-making framework for watershed-scale stormwater runoff control (Kaini et al., 2008, this meeting) involves identification of the most cost-effective combination of structural BMPs that meet target peak flow and sediment reduction criteria. This paper presents the second half of that framework: simultaneous generation of near-optimal alternative design strategies using a Euclidean distance metric. Structural BMPs included in this model include detention ponds, infiltration ponds, field borders, grade stabilization structures, and grassed waterways. Alternative designs are identified by coupling Soil and Water Assessment Tool (SWAT) and a Species Conserving Genetic Algorithm (SCGA). In addition, we demonstrate SCGA's flexibility and efficiency at generating alternative designs as well as varying numbers of alternatives. The model is demonstrated on Silver Creek watershed, a sub-watershed of the larger Lower Kaskaskia watershed in southern Illinois.

Multi-objective genetic algorithm (MOGA) and cumulative distribution function (CDF) are used to improve the accuracy of IDF curve. Rainfall durations are divided into short- and long-duration using root mean squared error (RMSE) and relative root mean squared error (RRMSE) between rainfall quantiles by IDF curve and at-site frequency analysis. RMSE could be used for estimating parameters of relatively long-duration, and RRMSE for short-duration. The compromised solutions could be ahieved through MOGA with two multi-objective functions. The duration separating technique called C0MBI_1 is suggested and the comparison with the five different parameter estimation methods provides COMBI_1 is superior to the other methods.

Operation of reservoir systems using a Bayesian Stochastic GA-based optimization model (BSGA) is investigated in this paper. This model considers the joint probability distribution of observed inflow and forecasted inflow to the reservoir. This way, the intrinsic and forecast uncertainties of inflow are considered. In this study, a multi objective approach that considers the interest of different agencies, water users and stakeholders in water allocation from the reservoir is developed. The proposed model maximizes an objective function based on the expected value of the Nash product. The Nash objective function includes utility functions of different stakeholders/water users as well as their relative authorities on the water allocation process. This work uses the general framework of Bayesian Stochastic Dynamic Programming (BSDP) proposed by Karamouz and Vasiliadis (1992). They utilized the Bayesian decision theory in the optimization algorithm for reservoir operation. In order to test the proposed methodology, the model is applied to the Satarkhan Reservoir system in the north-western part of Iran. The results show the significant value of the proposed model in water allocation from the reservoir considering the forecast uncertainty.

This paper presents a hydraulic modeling method to optimize a cost-effective design to expand the Marco Island wastewater collection system. Currently, approximately 60 percent of the city is served by individual septic tanks (decentralized system) and the remaining 40 percent is served by the existing centralized wastewater system. Marco Island has started the septic tank replacement program, which includes 14 sewer districts to be completed in 7 phases from year 2006 to 2012. One of the biggest design challenges is how to calibrate the hydraulic model of the existing wastewater collection system. The accuracy of simulation results is so critical because it is one of the most important factors on which key design decisions are based. Pressure gauges are used to continuously record pressure data at several lift station discharge lines. The recorded pressure data are then analyzed and compared with the simulated data to calibrate the modeling parameters and improve the model's accuracy and reliability. This will help design engineers better understand the existing collection system, and improve the future system development. Comparing actual field pressure data with the all pumps running at build-out model scenario ("worst case") suggests that the force main sizing and pump selections should not always be based on the worst case, which may prove to be too conservative. This less conservative approach may be more appropriate when it is not practical to upgrade pumps or force mains. Another design challenge is how to cost-effectively expand the existing wastewater collection system in phases in coordination with the existing facilities. The goal is to maximize the utilization of the existing gravity lines, lift stations, and force mains. The construction sequence of these sewer districts is mainly determined based on the configuration of the existing transmission system and hydraulic modeling of proposed developments. Other factors are also considered including sewer districts' own features (size, location, population, etc.), and the schedule for other proposed construction projects. The hydraulic modeling proves to be a cost-effective method to optimize the Marco Island wastewater collection system. More importantly, this method can wisely manage budgets and allocate money to projects with higher priorities based on recommendations from hydraulic simulations.

Developing a tradeoff between long-term objectives of reservoir operation such as water supply and short-term objectives like flood control and power generation is one of the challenging issues in reservoir operation management. In most of the monthly reservoir operation optimization models, flood control objective is only considered as a constraint for flood control storage and the probable flood damages are not usually taken into account. This can be a more important issue in cascade reservoirs, which provide more flexibility in achieving the long and short-term objectives. In this paper, a new approach for incorporating both flood control and water supply objectives in a monthly reservoir operation optimization model is presented. The optimization model is developed using Varying Chromosome Length Genetic Algorithm (VLGA). K-Nearest Neighbor (K-NN) is also used as a method for selecting the initial solutions considering similarities between reservoir inflows and storages in different water years. To incorporate the expected value of the flood damage in each month, peak flow frequency analysis has been carried out and the flood damages associated with each flood have been estimated by linking a hydraulic flood routing model with GIS tools for considering the land-use information in the flood plain. Damages due to deficit in supplying agricultural water demands are also calculated based on the functions of crop yield responses to deficit irrigation. The multi-objective optimization model is formulated to minimize the expected flood and agricultural water deficit losses, maximize reliability and resiliency, and minimize total deficit and surplus in supplying water demands. The developed model is applied to the cascade system of the Dez and Bakhtiari Reservoirs in southwest of Iran. The results of multi-objective model demonstrate efficiency of the model in finding pareto optimal solutions with more reliability and resiliency and less economic losses when compared with the single objective VLGA model.

A methodology by means of Geographic Information System (GIS) and Genetic Algorithms (GAs) for optimizing the spatial distribution of river monitoring stations for the detection of pollutant source in a river system is described. Two practical case studies are investigated to demonstrate the use of the method in (1) a regulatory monitoring plan for the Lanyang River System in northeastern Taiwan; and (2) a restrictive monitoring plan where the possible sampling sites are restricted to the existing flow gauge stations on the Lanyang River System. Plausible results were obtained encouraging the possibility of using GAs in river monitoring plan designs.

In this study, a Stochastic Varying Chromosome Length Genetic Algorithm model is developed in which reservoir inflow uncertaities have been taken into account. In this model, the basic concept of the Varying Chromosome Length Genetic Algorithm model (VLGA) has been used to develop a multi-objective stochastic GA model for reservoir operation optimization. The Fast Elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II) has also been utilized in development of the optimization model in order to be able to consider multiple objectives. The search and selection methods for the initial solutions are developed to increase the convergence speed of the model in order to be able to apply this model to multi-reservoir systems. The developed model is applied to the cascade system of reservoirs on Karoon River in Southwest of Iran.

U.S. EPA's Office of Research and Development has been evaluating the performance of point-of-use (POU) devices designed for use in homes and small businesses for many years. In collaboration with the University of Cincinnati, a series of pilot-scale tests were conducted on a Matrix Membranes ultrafiltration (MMUF) system at the U.S. EPA Test and Evaluation Facility in Cincinnati, Ohio. The MMUF system operates at a low flow rate (< 2 gpm) and feed pressure (< 30 psi). The polyethersulfone (PES) membrane (2" x 21") is designed for high flux rates with inside-out operation. Membrane integrity tests require the injection of compressed air (10 psi) into the closed system to check for breakthrough or air bubbles in the membrane. The MMUF system requires back-flushing when the filtrate flow drops 25%. The chlorine resistant membrane consists of 500 hollow fibers with 0.8 mm inner diameter and 1.50 mm outer diameter and contains 5.67 square feet of filter surface area. The membrane is cleaned with chlorine (2–200 mg/L) at pH 11 using sodium hydroxide. The membrane has an average pore size of 0.2 μm and a Molecular Weight Cut-off of 100,000. The research study evaluated removal of turbidity (2, 5, and 10 ntu) and microbial surrogates (3 micron polystyrene latex (PSL) beads, MS-2 bacteriophage, and E. coli). Other parameters of interest included system flux, runtime, raw water characteristics, and operating cost. Results are summarized and presented on turbidity and microbial removal efficiency.

The waterborne disease outbreaks have been a constant reminder of the critical importance of ensuring safe drinking water. Properly designed and operated public water systems, either large or small, are required to protect public health. This paper presents the results of tests conducted on a multi-layer cartridge based small system that combines physical filtration with chemical adsorption and ultraviolet light disinfection. The system was challenged with test water containing different levels of turbidity, a number of biological contaminants including B. subtilis, E. coli, MS2 bacteriophage and Polystyrene Latex (PSL) beads (as a surrogate for Cryptosporidium) and a number of chemical contaminants including methyl tert-butyl ether (MTBE), high chlorine concentrations, drinking water treatment disinfection byproducts (DBPs) including trihalomethanes and haloacetic acids, arsenic and diazinon. This paper benchmarks the baseline performance of the system in removing physical, biological and chemical contaminants and identifies the areas for further development. The applicability of the system as a home water security device was evaluated.

As a final barrier before consumption, properly designed and operated Point-of-Use (POU) treatment systems are important for safe drinking water supplies. POU treatment devices have gained importance for protection against intentional or accidental contamination of drinking water supplies. The events of September 11, 2001 have further emphasized the importance of POU devices in this regard. This paper summarizes the results of pilot-scale studies that were conducted at the U.S. Environmental Protection Agency's (EPA's) Test and Evaluation (T&E) Facility in Cincinnati, Ohio, to evaluate the performance of three different POU systems for removing microbiological contaminants in drinking water. Two of these systems were based on filtration through electrostatically charged media and the third system incorporated a reverse osmosis (RO) membrane. The systems were challenged with a number of microbiological contaminants including Cryptosporidium, E. coli, MS2 bacteriophage, B. subtilis and polystyrene latex (PSL) beads (as a surrogate for Cryptosporidium). The results demonstrated that these POU systems were effective in removing the target biological contaminants in accordance with the standards presented in the U.S. EPA "Guide Standard and Protocol for Testing Microbiological Water Purifiers".

Centralized drinking water treatment and distribution alone may not always be the most practical or cost-effective option. Also, some consumers seeking a proactive measure to reduce exposure to pathogens and chemicals not currently monitored or regulated might consider employing a POU/POE system. In addition, mobile POE and POU systems may have a proactive or reactive role in providing short-term treatment during natural disasters and protecting high asset facilities. Four POU and two POE technologies employing combinations of RO, carbon adsorption, and other components were tested to evaluate capabilities for reducing microbial and chemical challenges under varying operating conditions. Microbial challenges included the bacteria B. diminuta and H. psuedoflava, and the coliphage viruses fr, MS2, and Phi X 174. A number of organic and inorganic chemical challenges were also conducted. The POU/POE devices evaluated in these studies showed varying capabilities for the removal of contaminants in water. Some devices showed significant contaminant reductions, but even the best performing technologies had some units from different production lots that showed microbial challenge organisms in their effluents. The POU RO components alone are not absolute microbial and chemical barriers. Despite shortcomings, POU/POE systems may be beneficial in a number of applications for individual consumers and as a managed strategy for some water utilities or emergency planners/responders.

A set of software tools has been developed to enable performance testing of candidate on-line sensors in a utility-specific contaminant warning system design using simulation methods. Specific sensor performance characteristics such as noise, drift, detection level, and sampling rate can be input into the simulator and contamination scenarios can be run with a contaminant transport model such as EPANET using utility-specific pipe layouts. The sensor simulator is coupled with event detection software and together the two modules can provide an indication of how well the sensor will perform in a specific utility setting with user-defined contamination events. Water quality baseline data from utility measurements using on-line sensors are also incorporated into the analysis for a more realistic simulation. The software enables a determination of the rate of true positive, false positive, true negative, and false negative events during the simulation. Results from this analysis reveal that on-line residual chlorine and total organic carbon sensors combined with several different event detection algorithms can provide reliable detection for a variety of chemical contamination events. Study results further indicate this simulation tool concept is useful for pre-installation evaluation of contaminant warning system design in a specific utility setting.

There is an increasing need for developing strategies to face droughts because of high dependencies of societies on water. This need has been intensified due to the water scarcity and the impact of climate change. The frequency and magnitude of droughts have been increased in many parts of the world because of climate change effects. When facing droughts, using sound strategies in real time could decrease the drought damages considerably. Virtual Drought Exercise (VDE), a strategy for drought management, can increase a system's readiness to deal with droughts. VDE gives the decision makers the opportunity to simulate the disasters without taking any risk. In this study, an algorithm for VDE has been presented. In developing VDE scenarios, the first step is identification of key triggers of drought. In this paper, after determination of all effective triggers on drought management, their consequences are evaluated using the unranked pairwise comparison technique. The triggers with greatest impact can be used for developing VDE scenarios. The Ahar-chay river basin located in northwestern Iran has been as case study of this paper. Utilizing the proposed scenarios, decision makers can prepare the system for better management of water shortages during droughts.

The past 40 years have witnessed many changes in the fields of water resources and environmental engineering. In some respects, the tools and methods used to analyze and design water systems have undergone significant changes. However, in other respects, there has been a gradual evolution but the underlying concepts and methodologies have changed very little. This paper is part of session that will first look back at how water resources and environmental planning has changed over the past 40 years and then attempt to look over the horizon at what water resources and environmental engineering will look like 40 years from now by exploring the insights of a select group of leading engineers and scientists. Topics may include how the politics of global warming or the advent of new technologies such as nanotechnologies influence water resource and environmental engineering policy and practice. A panel of experts will discuss these future changes and attempt to answer the fundamental question of what we must do to prepare ourselves and those for whom we have responsibility to face future environmental and water resource challenges. This is the initial event in a series of future activities planned by the Emerging and Innovative Technology Committee to look at 2050 visioning in the water resources and environmental area.

As a young mining engineer early in my career I was attracted to Western Australia in the late 1960's when the iron ore mining business was in the midst of a tremendous boom. I met a young lady there who would later become my wife and so established a close and permanent tie with this interesting but remote region of Australia.

Relatively speaking, much is known about the construction prowess of Roman engineers. The existence of structures such as amphitheaters like the Colosseum in Rome, temples like the Pantheon, aqueducts like Pont du Gard, structures like Hadrian's Wall, and the remnants of the network of Roman roads that crisscrossed the Empire give mute testimony to both how big and how well they could build. Similarly, the great churches of Florence, Chartres, Lincoln, Cologne and dozens of others give witness to the abilities of the cathedral builders of the Middle Ages. Although there are great gaps in our knowledge of the identities of the builders and their methods, what we know is encyclopedic compared to our knowledge of construction activities during Europe's "Dark Ages"—the seven centuries between the fall of the Roman Empire and the rise of the great churches. This review reveals, however, that "building big" continued through those years.

James Buchanan Eads (1820–1887) is today recognized as one of America's greatest citizens, and in 1932, the Deans of American Colleges of Engineering named him as one of the five greatest engineers of all time, placing him in the company of Thomas Edison and Leonardo Da Vinci. He is perhaps best known for his role in constructing the St. Louis Bridge, now called the Eads Bridge, across the Mississippi River in St. Louis, Missouri. This bridge was completed in 1874, and at the time it was the longest span bridge in history and was the first of its kind to employ a steel arch design. As a testament to Eads' engineering expertise, the bridge is still in use today by St. Louis's Metro light rail system and by highway traffic. It was, and still is, considered a great accomplishment of engineering and aesthetics. Though Eads was never formally educated as a civil engineer, his years of experience as a river salvage captain helped him amass his vast knowledge of the workings of the Mississippi River, and provided him with the wealth and influence necessary to launch future business ventures, including building the St. Louis Bridge. The accomplishments of James Eads also included design and construction of steam-powered ironclad warships during the Civil War; these ships were pivotal in the defeat of the Confederacy. In all, Eads intimate knowledge of the River allowed him to make several long lasting contributions to both his country and his profession.

In this paper, the history of water development activities related to Persian, Egyptian and other civilizations in the Middle East are discussed. The historical developments of Qanats, Madies, small dams as well as drainage systems, some still functioning, are addressed. An overview of Nile River with it's over 1000 years of hydrological data, is presented. This river has been the centerfold of many water development activities that have affected the life of many people and the social and political developments in the north-east Africa. This discussion is followed by an overview of different stages of Aswan dam construction and operation. Finally, construction of many large dams as well as irrigation networks and desalination plants and water development in the last 30 years in the Middle East are discussed.

The Roman engineers were at the forefront of science and their engineering heritage included some magnificent aqueducts, many of which are still standing. While some scholars suggested that Roman engineers did not know the basic principle of conservation of mass, the Roman aqueducts provide a clear demonstration of the high level of hydraulic engineering expertise. The successful design and operation of these outstanding systems were massive achievements by modern standards. The development of regulation basins, culverts and energy dissipators was far from obvious. It is the writer's opinion that the leading Roman hydraulic engineers involved with the major aqueducts in Gaul and North-Africa understood the concepts of continuity and momentum.

Over the last 150-plus years, California has been a leader in the development of water resources and infrastructure, which have more recently involved transferring scarce water from available sources to needy destinations. The 1930s Central Valley Project involved large dams, lengthy canals, pumping stations, and other important features. It helped turn the Central Valley into one of the most productive agricultural areas in the world. This paper traces the important history of California's water resources and infrastructure development; highlights the CVP's origin, planning, design, construction, operation, and recent developments; and focuses on some of the people who made major contributions.

Until the catastrophic dam failure on Kauai during the spring of 2006, many, if not most people didn't realize that Hawaii had any significant dams. In fact, there are over 130 dams in the inventory that are large enough to be under the State's jurisdiction. Over half of these dams are classified as "high hazard" dams with the potential to cause loss of life and property should a failure occur. This number may in fact be low. At the time of failure, the Ka Loko Dam was classified as a low hazard dam but subsequently killed seven people and swept away a number of homes. Many of the dams in Hawaii were constructed around the turn of the century (1900) or in the few decades following to supply water for irrigation to support the sugar industry. The consequence of this is that not only are most of the dams old and aging, but many were not constructed with a high level of engineering. Furthermore, the natural soil and foundation materials in Hawaii are typically poor with respect to quality dam construction. Review of a number of dams in Hawaii shows a history of problems, a number of failures and other "incidents" which have surfaced in recent years. These will be described along with how the State is coping with its aging dam inventory.

Harris County, home to the City of Houston, is no rookie to flooding and flood control tactics. While the population in 1836 was less than 2,000 citizens, it is now the third most populous county in the United States facing new development and new flood control needs on a regular basis. Downtown Houston experienced devastating floods in 1929 and 1935 which led to the development of the Harris County Flood Control District (HCFCD) in 1937. Over the past 70 years, the HCFCD has taken on the challenging task of keeping the flood control tools, policies and systems up to date with the rapid urbanization of the County. This paper will review a timeline of the County's growth and flooding alongside the past 70 years of community accomplishments.

Problems in science and technology are frequently complex and require the collaborative efforts of large teams with a wide range of expertise. It is, therefore, not surprising that interdisciplinary programs continue to be attractive across campuses in the U.S. The benefits from such programs are numerous. First, faculty from different departments, and even colleges, can participate in multiple interdisciplinary programs. In addition, interdisciplinary programs frequently allow admission of students with varied backgrounds, compared to traditional departments that may have stricter background requirements. The variety of faculty and student backgrounds contributes greatly to a unique and stimulating experience. Unfortunately, however, interdisciplinary programs may face significant challenges in the traditional university structure. These challenges are often traced to lack of resources and lack of faculty and curriculum control. Management of scarce water resources in the arid U.S. Southwest is particularly suitable to an interdisciplinary approach, because in addition to hydrologic engineering and sciences, political and socioeconomic aspects must also be considered. This paper explores some of these challenges and opportunities and offers suggestions to maximize the positive and minimize the negative aspects of interdisciplinary programs.

Interdisciplinary Graduate Programs (IDGPs) have grown in number and notoriety throughout the past 20 years, yet fundamental challenges regarding resource allocation and control remain mainly unresolved. The author herein presents his own admittedly biased views regarding the major challenges to running successful IDGPs and what steps might be taken to address these challenges. The identified challenges include the control of resources (personnel and funding), communications, disaggregated space, and fundraising.

Project-based service-learning (PBSL) is a valuable pedagogical tool which confers educational benefits that extend far beyond the charter of traditional classrooms. This unique form of experiential education is based on a synergistic model in which community service is integrated with the academic learning objectives. In the context of providing engineering services to poor communities in developing countries, students are able to participate in all aspects of the engineering design process including problem formulation, consideration of alternative technologies, and design, construction, and evaluation of selected technologies. The reciprocal relationship that forms between the students and community nurtures personal growth and a deeper sense of social responsibility among students while empowering communities as they become more self-sufficient. As an advocate of this pedagogy, Tufts University has provided opportunities for students to work on water infrastructure projects in Ecuador, El Salvador, Ghana, and Tibet over the past four years. Although the challenges students face are unique to each project, overcoming them allows students to develop problem solving skills that they would not otherwise get in their college education. Over the last few years, concerns have escalated among many national organizations over whether today's engineering students are being adequately prepared for future challenges; globalization, sustainability, complexity, and adaptability. To address this situation, the National Academy of Engineering (NAE), the Accreditation Board for Engineering and Technology (ABET) and the American Society of Civil Engineers (ASCE) have all generated reports aimed at reforming the existing engineering curriculum. As a result, the NAE's Engineer of 2020, ABET's Engineering Criterion 3 (EC 2000), and ASCE's Body of Knowledge (BOK) all aim at shifting the existing paradigm of engineering curriculum towards a more well-rounded education. The commonality among these three documents is improving students' problem solving techniques. The future will inevitably bring unanticipated crises; engineers will need to identify the problems and collaboratively formulate innovative, feasible solutions. This research hypothesizes that service-learning can serve as a mechanism that will allow students to develop the necessary problem solving skills. To investigate this hypothesis, an education assessment instrument is employed to examine whether students who have participated in service-learning projects have stronger analytical, practical, and creative abilities than students who have only been exposed to the conventional "classroom" education.

The numbers of female and minority students enrolled in engineering schools have been increasing slowly within that previous two decades, however there is still a relatively small percentage drawn to the field of civil engineering. As a consequence, there is a need to educate young people about the profession to encourage under-represented individuals to appreciate the contributions of engineers and encourage them to become civil engineers. The summer institute held at the University of Alabama in Huntsville consisted of bringing middle school students, to the campus for a week of interactive science and engineering experiences. The strategy of this program was aimed at producing students who know "how to find out" and "how to examine and evaluate evidence." The participants gained knowledge about the role of engineers in society, as well as practiced applying simple science concepts to solve design problems.

The outcomes criteria of the Accreditation Board for Engineering and Technology (ABET) mandate that new graduates with a degree in civil engineering must demonstrate a proficiency to engage in life-long learning. Many Civil Engineering programs have redesigned their curricula to meet this objective. In teaching hydrology, there are several ways in achieving this goal. These include exposure to the details of hydrologic engineering design through field trips to completed and on-going projects; and, through guest lectures in class by practicing hydrologic engineers. Another approach is to exploit the potential of letting undergraduates take advantage of resources that are available to them in the public data bases. This paper outlines how the tools for life-long learning are incorporated in an upper-level undergraduate course in hydrology. Synchronized with the sequence of topics in the traditional engineering hydrology course, the collection and analysis of geographic and hydrologic information from external sources are inter-woven in the syllabus. The topics range from using federal web sites to explain the importance of hydrology in sustainable engineering, the delineation of watershed boundaries through extraction of GIS information from federal and state sources and the access of watershed information from web sites to download rainfall and runoff data to validate runoff prediction models. These resources continually evolve and water resources professionals will need to keep up-to-date after they leave the campus. In-class experience with examples will be presented.

University of Vermont College of Engineering and Mathematical Sciences (UVM-CEMS) and the Barrett Foundation have established a scholarship program for undergraduate students in engineering, physical and natural sciences who wish to pursue independent research aimed at solving environmental problems. The Barrett Scholarship program was specifically designed to create a more knowledgeable and effective engineering workforce by reinforcing the technical (e.g., systems analyses, information technology (IT)) and "soft" skills (e.g. teamwork, communication, leadership) needed for solving environmental problems. The intent was to help retain student interest early in their engineering careers when few of their first or second year classes have any engineering or real-world applications. Fourteen scholarships have been awarded over the three-year pilot project covering a range of topics. During the summer research months, the Barrett Scholars meet regularly with their advisors and project affiliates. They prepare written and oral presentations to communicate their work and many of them participate in campuswide student research events. Past recipients report their experiences with the Barrett Scholarship program to be extremely valuable in their job searches, interest in graduate studies and to their work experience.

Leading scholars in the area of Cognitive Science and Educational Methodologies have concluded that it is essential that students need to be taught in a learning environment that enables them to acquire real-world problem-solving skills. The 21^st century workplace does not need employees who have just mastered a particular body of information, instead it prefers to have liberally educated workforce who have mastered written and oral communication skills in addition to acquiring knowledge in their chosen discipline. Educators should not allow the students to wonder whether they have been learning anything that would actually serve them in the workplace, upon graduation. It is also important to recognize that state legislatures have introduced and are in the processes of introducing demands for outcome assessment. In this paper the author outlines how assessment techniques he has generated, can help an instructor in promoting a learning environment. Furthermore, he also provides initial results of his findings pertaining to assessment data he has collected.

Project Lead the Way (PLTW) is a highly successful K-12 pre-engineering program taught in high schools across the country. The High School Program is a four year sequence of courses which, when combined with traditional mathematics and science courses in high school, introduces students to the scope, rigor and discipline of engineering prior to entering college. The PLTW curriculum was first introduced to 12 New York State high schools in the 1997 – 98 school year and was developed at the Rensselaer Polytechnic Institute. A year later, PLTW field tested its four unit Middle School Program in three middle schools. Today, the programs are offered in over 1,300 schools in 45 states and the District of Columbia. At least 20 high schools in Colorado have implemented the program into their curriculum. The purpose of this paper is to describe the benefits and implementation of the program in Jefferson County Schools in Colorado. The benefits and problems with the program will be identified. Students and teachers will be interviewed.

The Missouri University of Science and Technology is Missouri's technological university where over 80 percent of the undergraduate student population majors engineering. Total on-campus enrollment at S&T has been increasing in recent years, and now tops 5,500 students. Part of the successful recruiting effort is S&T's comprehensive collection of summer precollege programs. The largest and oldest precollege program is called Jackling Introduction to Engineering. This highly successful program which is more than 30 years old hosts over four hundred high school students annually over three summer camp sessions. This week-long camp, geared to high school rising juniors and seniors, helps students discover the excitement of engineering and to identify the kind of engineering that is best for them. They learn about the engineering profession and solve some simple engineering problems. They learn about the different engineering majors offered at S&T, they tour some of the engineering and science programs, and they participate in afternoon hands-on activities in the programs that they select. They live in residence halls for five nights, walk daily on campus, attend classes and work in labs. They have ample contact with faculty, graduate students, and undergraduates. Geological engineering and environmental engineering faculty have offered field trips of environmental interest, and these activities are representative of activities which other academic programs offer.

As an integrated part of management plan against the elevated air pollution, typical monitored emission inventory was presented for metropolitan area of Beijing in 1999. The air pollutants of concern were fine particulate matters (PM₁₀), sulfur dioxide (SO₂), and nitrogen oxides (NO_x). Emissions of these air pollutants were estimated by suitable emission factors and evaluated in three categories of point, area and line sources. Total yearly mean emissions in the studied area were estimated as 103,298 tons of PM₁₀, 209,914 tons of SO₂, 225,394 tons of NO_x. To assess the air quality, Industrial Source Complex-Short Term (ISCST3) dispersion model was applied by combining measured emissions and meteorological data with 1 hour temporal and 1km x 1km spatial resolution. Validity of model was verified by comparing the monitored data from Beijing's Environmental Protection Bureau with the model values predicted. Demonstrated by Geographical Information System (GIS), results indicate that the levels of PM₁₀, SO₂, and NO_x were serious and endangered the regional human health. While area source accounted for 83.8% of PM₁₀ concentration distribution and 79.2% of SO₂ concentration distribution respectively, line source contributed 73.5% of NO_x concentration distribution. It reveals insight on emission control priorities and future implementations of effective control technology.

Pollutant emission rates for constant speed conditions distinctly differ from inconstant speed conditions of vehicles. In intersections, vehicles are forced to reduce speed, change direction, and most likely, stop for a long period of time. Pollutant CO has the most emission changes in intersections because of dramatic speed change in intersections. In this investigation concentration of CO in one of most populated and residential intersections of Iran's capital have been modeled using software hyroad. Modeling practice has been done considering several parameters, with the extent of data available on each parameter, including; traffic flow, meteorological and weather characteristics, site specific characteristics and realistic characteristics of vehicles. Amount of CO concentration obtained from model has been compared to recorded amount of CO for specific period of data available, reliability of model to predict the actual concentration of CO in this intersection has been assessed. Results shows that predicted amounts are less than actual site amounts but there is some apparent similarity associated with the change patterns of concentration, i.e. the highest and lowest concentration levels occur in the same time but with higher amounts for predicted amounts in all times.

The Clean Air Act requires the US EPA to regulate emissions of hazardous air pollutants (HAPs) under regulations know as Maximum Achievable Control Technologies (MACTs). These MACTs are embodied in National Emission Standards for Hazardous Air Pollutants (NESHAPs). MACT standards are developed for individual source categories, such as Publicly Owned Treatment Works (POTWs) and Industrial, Commercial, and Institutional Boilers and Process Heaters. EPA initially listed 174 source categories for regulation under MACT standards, and is required to evaluate the list every 8 years. The majority of the MACT standards can be found in Title 40 Code of Federal Regulations Part 63 (40 CFR 63); the MACT standard for each source category is located in a separate subpart of 40 CFR 63. In addition to the source category specific requirements found in each subpart there are General Provisions that apply to each source that is regulated by a MACT standard. These General Provisions are found in 40 CFR 63 Subpart A. Applicable MACT requirements are generally included in each facility's air quality operation permit and become an important element in facility compliance. This paper provides a brief overview of the MACT rules, a discussion of the General Provisions, and an update on two recent changes to the MACT rules.

This presentation discusses a comprehensive methodology for designing odor control systems for wastewater plants and lift stations. Historic design of odor control systems has revolved around a 99% removal of hydrogen sulfide (H₂S) and a typical influent concentration of 20 to 50 ppm, or a two log removal. Detection of H₂S by the human nose is at the 0.2 ppb level, with recognition of the unique H₂S odor at 0.5 ppb. An additional three log removal is required between the exhaust stack and the closest customer's nose. Oftentimes, this secondary design element is not considered. The author's approach addresses this secondary design element as part of an overall modification to the traditional odor control design. The author also stresses the need for engineers to improve communications with clients to determine client needs.

Preliminary experiments to investigate the fate of 17α-ethinylestradiol (EE2) during nitrification were conducted. Sorption experiments were performed by incubating inactivated ammonia oxidizing bacteria and various heterotrophic cultures in the presence of ¹⁴C-EE2 at 10 μg/L. Biotransformation experiments utilized LC-MS and LC-ITMS analysis of supernatant collected during batch cultivation of monoculture of Nitrosomonas europaea with EE2. Results confirmed that sorption of EE2 onto heterotrophic biomass is an important mechanism that must be considered when describing the fate of EE2. During batch incubation with N. europaea, 98% of EE2 was transformed, producing a unique metabolite corresponding to a mass/charge ratio of — 386 m/z. Short term inhibition study results also suggest that inhibition of respiration in N. europaea as measured through nitrite generation rates is not significant at concentrations at or below 1 mg EE2/L.

The recent detection of a variety of emerging organic contaminants (EOCs), such as Pharmaceuticals and personal care products (PPCPs), in municipal wastewater effluent has raised concerns about the presence of these compounds in reclaimed water and the environment. The sludge retention time (SRT) is a critical operational parameter for secondary wastewater treatment that can be potentially optimized to enhance the removal of EOCs by biodegradation. The objective of this study was to assess the effect of SRT on the biodegradation of PPCPs during activated-sludge wastewater treatment using an experimental setup that consisted of a laboratory-scale flow-through activated-sludge system. The activated sludge system was operated at SRTs of 1, 5, 10, 35, 55, and 120 days and critical SRTs were determined for the removal of 18 PPCPs.

Environmental Public Health Tracking (EPHT) is the ongoing collection, integration, analysis, interpretation and dissemination of data from environmental hazard monitoring, and human exposure and health effects surveillance. The Centers for Disease Control and Prevention (CDC), in a cooperative agreement with 17 state and local health departments, is leading the initiative to build a national tracking network by drawing on expertise from federal, state and local agencies. As part of this effort, a national workgroup was formed to identify appropriate drinking water quality data and measures for inclusion in the tracking network. In order to identify current gaps in data and information, and assess the feasibility of developing measures of drinking water quality, the EPHT drinking water workgroup assessed existing statewide and local water quality data sources. This assessment documented the availability and quality of centralized and electronic water quality and water system data that could be used to generate useful, nationally consistent measures for tracking spatial and temporal trends in drinking water quality. The results indicate that the data elements needed to generate public health based measures are centrally reported to the state agency responsible for regulating public water supplies, and are available in electronic format to EPHT programs. The most crucial data gap is the lack of information on the geographic extent and spatial distribution of water systems, making the linkage of these data with population based census estimates and other health effect data virtually impossible. The entire assessment process benefited EPHT as it provided a better understanding of the data available from different states and the feasibility to generate measures to assess drinking water quality.

It has been hypothesized that N-nitrosodimethylamine (NDMA), a potent carcinogen that is present at high levels in the ground water beneath the Olin Chemical Company site in Wilmington (Massachusetts), has contaminated the town's water supply wells. NDMA was not manufactured or used at the site, nor is it known to be a byproduct of chemical manufacturing activities at the site; thus it is suspected that NDMA precursor compounds were present in waste materials released on the site, and that the precursors then reacted in the subsurface to form NDMA. We undertook this study to establish a timeline for the release of NDMA precursor compounds into the aquifer, investigate the likely reaction mechanisms and kinetics of NDMA formation, and estimate the travel time of NDMA from source areas to the town of Wilmington's water supply wells. Based on the history of chemical waste disposal at the site, there is strong evidence for nitrosation of organic nitrogen compounds as being a major pathway leading to NDMA formation at the site. In particular, the manufacture Nitropore 5 PT, a blowing agent, required the use of sodium nitrite as one of the ingredients and produced dimethyl formamide as a waste material. Dimethyl formamide can hydrolyze to form dimethylamine, which reacts with nitrite by the nitrosation pathway to form NDMA. The kinetics of NDMA formation by nitrosation are relatively rapid (timescales of hours-to-days), suggesting that NDMA was formed onsite soon after the precursors were dumped there. A ground-water model was constructed using MODFLOW to estimate NDMA travel times between the site and the town wells. The trajectories of individual particles introduced into the model at the NDMA source area were simulated assuming steady-state hydraulic conditions. Two transport simulations were carried out based on 1965 and 1973 as being alternative estimates of the earliest production dates of Nitropore 5 PT, the suspected major source of NDMA precursors. For the 1965 simulation, NDMA started to arrive in the wells in 1971, and reached a peak concentration at the Butters Row well 1 in 1980. The 1973 simulation resulted in a 1977 arrival and a peak concentration at the Butters Row well 1 in 1983. In both cases, the wellhead concentrations of NDMA decreased from their peak concentrations, but were not eliminated entirely, due to the capture of NDMA by nearby industrial wells. Although the wells were shut off in 2003, it is suspected that chemicals in the water supply may be linked to high rates of childhood cancer. Results from this study could be useful in determining whether temporal correlations exist between NDMA in drinking water supplies and disease incidence among Wilmington residents.

Southern LNG, Inc. (SLNG) is one of only four liquefied natural gas (LNG) import terminals currently operating in the continental United States. Because LNG import and storage terminals are a critical component of the country's diversification of natural gas reserves, infrastructure, and reliable energy services, as many as 40 LNG terminals are either before the Federal Energy Regulatory Commission (FERC) or are being discussed by the LNG industry in the United States. In 2005, SLNG initiated the Elba III Terminal Project, a major federal project requiring an extensive environmental review process pursuant the National Environmental Policy Act (NEPA). FERC was the lead federal agency responsible for coordinating the Environmental Impact Statement (EIS), with the US Army Corps of Engineers, US Coast Guard, and the National Marine Fisheries Service acting as cooperating agencies. This paper provides an overview of SLNG's experience with FERC and the cooperating federal agencies during preparation of the EIS required for authorizing the Elba III Terminal Project.

This paper describes some of the technical and regulatory issues involved with obtaining permits for the drilling and production phases of natural gas wells in the north Texas area. Natural gas well drilling in the Dallas and Fort Worth metropolitan area has increased dramatically over the past 5 years. The Barnett Shale Formation activity has increased substantially due to advanced and complex horizontal drilling techniques which allow drillers to go beneath adjacent property owners with lower or minimal surface impacts. In a study conducted by the Fort Worth Chamber of Commerce, the Barnett Shale is contributing $5 billion annually and 55,000 permanent jobs in North Texas. Fort Worth city officials estimate that over 20 years, lease bonuses will provide $742 million for municipal offers and property tax revenues from the wells could bring that total to more than $1 billion. The complexity of locating suitable urban well sites, pipelines, and production facilities is much more difficult than in rural areas. Most cities in the Dallas Fort Worth area have adopted restrictive oil and gas well drilling ordinances and regulations. Floodplains are often the only sites available that are outside of the distance limitations or restrictions for drilling near homes, parks, and other sensitive facilities. Engineers and other professionals are involved with several different phases of the Barnett Shale gas well industry which includes: 1) Permitting Natural Gas Wells in the Floodplains throughout the Metroplex; 2) Preparing GIS-based maps to determine feasible locations for drill sites; 3) Providing route studies for pipelines; and 4) Delineation of wetland boundaries or "Waters of the US", to be avoided by the drilling and production facilities; and 5) Field surveying gas well pad sites and lease boundaries. Much of this effort has been an attempt to guide exploration companies in minimizing the environmental impacts of this activity. The energy companies have significant political and financial resources.

In order to assess the impact of natural resources development projects such as mines on water bodies, it is crucial to have an appropriate water quality-monitoring program in place. Real-time water quality (RTWQ) monitoring is suited to monitoring the impact of mining projects especially those situated in remote locations. To illustrate the successful use of RTWQ monitoring as a regulatory performance tool, case studies are presented of two real time water quality networks that were established as a part of the environmental permitting process for the Voisey's Bay Nickel Mine project site in Labrador and the Aur Resources Copper Zinc Mine site in Newfoundland. The case studies detail the need for the establishment of the networks, the installation of the networks, the details of the networks, the Quality Assurance program, the RTWQ public web page and the experience encountered since the networks were established. Also discussed is the use of the data collected by the RTWQ network by various stakeholders. The challenges of using RTWQ for mining sites are also discussed.

The relatively recent U.S. Supreme Court case that was expected to reduce confusion and shed some light on the jurisdiction of the Corps of Engineers and EPA over wetlands and streams in the United States has primarily resulted in confusion and frustration on the part of both regulators and those being regulated by the agencies. The Supreme Court decision had something for everyone — except a clear conclusion of what should be included as "Waters of the United States". This lack of clear guidelines or a "bright line test" has led to new guidance from the Corps that attempts to apply the muddy conclusions of the Rapanos decision. The decision from Rapanos is evaluated herein and the decision presented in a way that is (hopefully) more clearly understood than the three conflicting opinions contained therein. Tables have been developed that can be used to help navigate the already muddy waters of determining which streams and wetlands are jurisdictional and which are not.

In 2006, 67-km of 12 streams in the Great Smoky Mountains National Park (GRSM) were listed on the 303d list as impaired due to low pH from atmospheric deposition and unknown sources, requiring a TMDL to be developed. The GRSM receives some of the highest rates of atmospheric acid deposition in the U.S. in the form of sulfur and nitrogen oxides, which can cause stream pH to drop below 5.0 (minimum of 4.0) for 2-days or longer. Acids enter poorly buffered streams through wet deposition and from naturally occurring organic acids and accumulated dry deposition flushed from watersheds, temporarily reducing pH and ANC in streams. Stream acidification has been shown to have damaging effects on the health of aquatic ecosystems and biota, and is suspected to be a primary cause of the extirpation of native brook trout (Salvelinus fontinalis) in six headwater streams in the GRSM. To develop appropriate TMDLs, it is imperative to understand the environmental processes associated with stream acidification, determine system responses to atmospheric deposition, and evaluate impacts to biota. The objectives of the current research are to 1) characterize the chemical constituents in stream water during baseflow and stormflow in three forested watersheds in the GRSM, 2) identify potential mechanisms responsible for episodic acidification, and 3) evaluate physiological distress in native brook trout during episodes of stream acidification. Conductivity, pH, turbidity, stage height and temperature were monitored continuously (15-minute intervals) at three study sites using multi-parameter data sondes. Baseflow grab samples and precipitation samples were collected; automatic water samplers captured stormflow samples. Stormflow, baseflow, and precipitation samples were analyzed for pH, ANC, trace metals, and major cations and anions. To provide evidence that native brook trout are impacted by stream acidification, in situ bioassay experiments were conducted. Changes in native brook trout physiology were determined during two acid runoff episodes. Brook trout were put in cages at the three sites and fish were sampled before and after stream acidification events. To assess physiological stress in brook trout as a response to acid conditions, whole-body sodium concentrations of individual fish were evaluated. ANC and pH depressions were observed during all stormflows at the three study sites. Sulfate, nitrate, and organic acid concentrations increased during runoff episodes. Base cation concentrations generally increased during stormflow at two stream sites, but diluted occasionally at the third site. The relative changes in ion concentrations were used to determine which ions (acids) were most responsible for ANC depression. ANC contribution analysis indicates acid deposition may be the primary cause of episodic stream acidification, but it appears organic acids and cation dilution may also contribute. Results of the in situ bioassay demonstrate that stream acidification can negatively affect native southern brook trout physiology in the GRSM under actual field conditions. Trout lose the ability to regulate critical blood ions, as exemplified by a loss of whole-body sodium, when stream pH dropped below 5.1.

Membranes are becoming an important commodity in water and wastewater treatment. There are four major membrane categories, classified by membrane pore size, that are commercially used at the present time: Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO). All four membrane categories are commonly used in water and wastewater treatment to achieve the goals of Drinking Water Guidelines and Standards. They are also used to produce desalted and/or Ultra Pure Water (UPW) for different industrial and other needs, such as power plant make up water, electronic chips manufacturing, food industry, pharmaceutical, medical and others. Membranes in wastewater treatment have lagged behind membranes used in treating water. However, the wastewater market area is growing fast, benefiting from the experience and technology issues that water applications have overcome. Nearly every known conventional water treatment technology and process has a membrane equivalent. For example, clarifiers and media filters can be successfully replaced by MF or UF membranes, softening with Cold Lime or Softeners can be achieved by substituting NF membranes, and ion exchange units can be replaced by RO membranes. Even mixed beds ion exchangers have a replacement membrane equivalent: Electro-Deionization (EDI) technology can achieve the strict standards required to produce ultra pure water (UPW) for the needs of the power and semiconductor industry. The proper and most efficient water treatment process for a particular facility has to be selected based on the specific project conditions, technical requirements, and economical parameters (capital and O&M cost). That is why the majority of membrane applications presently on the market are combinations of conventional and membrane technologies. However, a growing number of water treatment systems contain membrane processes only (membrane and/or integrated membrane system). One efficient application of membrane technology is the upgrade of existing operational plants. By implementing membrane technologies, the plant's system size (water flow), and effluent quality can be upgraded significantly at a lower relative cost than achieved by applying conventional treatment only. Most conventional processes require more chemicals to operate the system, while membrane technologies are "cleaner" processes. This presentation provides a brief history of membranes, presents the characteristics of the different types of membranes, and discusses the exponential growth in the number of installations. It will also cover applications for water recycling, water reuse and desalination, and the challenges that membrane treatment processes face. This presentation will conclude with a discussion of recent membrane developments and how these developments may impact the future of membrane applications Information provided in this presentation may help Engineers, Utilities, and Government and Private Sector representatives better understand the features and applications of membrane technologies, membrane selection and differences, evaluation and design concepts, procurement of membrane equipment, and balance of the treatment plants.

Two laboratory-scale flat sheet membrane bioreactors (FSMBR) with three flat sheet membrane cartridges in each were set up to treat a synthetic biodegradable industrial wastewater. Four stress conditions were employed during the study including different organic loading rates (OLR phase), high salt concentration (salt phase), temperature spikes (temperature phase), and mixed liquor suspended solid (MLSS) concentration (MLSS phase). This study investigated the impact of the stress factors on membrane fouling and evaluated the performance of the FSMBR. Under the imposed stress conditions, the experimental reactor had a smaller particle size, higher average effluent COD concentration, and lower sludge filterability. The experimental reactor also fouled at a faster rate than the control reactor. The results showed that imposed stress conditions had an effect on the bacteria in the MBR which impacted sludge characteristics such as filterability, polysaccharide production, floe size, effluent COD concentration, effluent color, and most importantly the rate of membrane fouling.

The hybrid membrane biofilm process (HMBP) is a new approach to achieving total nitrogen removal from wastewater, with great potential for retrofitting into existing plants. It incorporates air-supplying hollow-fiber membranes into a conventional activated sludge tank. The HMBP utilizes both attached and suspended growth to achieve TN removal. At the bench scale, the performance of the HMBP was assessed for a variety of nitrogen and BOD loading rates. The nitrification rate remained at approximately 1.0 gN m^–2 d^–1 despite BOD loadings ranging from 4 to 17 gBOD m^–2 d^–1 at a nitrogen loading of 1.7 gN m^–2 day^–1. Denitrification rates of 100% were achieved when sufficient BOD was available in the influent. Microsensor measurements indicated nitrite was the dominant form of oxidized nitrogen produced by the biofilm, showing that shortcut nitrogen removal was taking place. Fluorescence in-situ hybridization (FISH) tests on the biofilm revealed a unique stratification, with three distinct regions: AOB and NOB near the membrane, strictly AOB at intermediate depths, and AOB and heterotrophs at the outer edge of the biofilm. Pilot scale studies with municipal wastewater primary effluent (PE) indicated a reduced nitrification rate. With an average nitrogen loading rate of 0.6 gN m^–2 day^–1, the average nitrification rate was 0.4 gN m^–2 day^–1, with a maximum of 0.6 gN m^–2 day^–1. These rates are similar to aerobic fixed film systems (i.e., RBCs). However, unlike other fixed-film systems, reduction of nitrate/nitrite to below 1 mgN/L was consistently achieved in the pilot scale HMBP, without the need for an exogenous electron donor.

A study is performed to analyze the thermal performance of a cooling reservoir of an existing nuclear power plant with the addition of two new units. For the analysis, a one-dimensional multi-layer computer program is used. The program simulates the transient response of the cooling pond under imposed heat loads for the site historical meteorological conditions and plant operating conditions for specified pond characteristics. These results are used to investigate different condenser/circulating water system design parameters and determine the optimum parameters for the cooling water system for the expansion of the nuclear plant.

Recently, many electric power generation companies have a renewed interest in the development of new generation nuclear power plants. In response to that interest, several Early Site Permit and Combined License applications have been submitted to the Nuclear Regulatory Commission (NRC) seeking permits for new nuclear power plants. The application process requires the submittal of a Safety Analysis Report (SAR) for the site and power plant. The Safety Analysis Report requires probable maximum precipitation (PMP) flooding analysis for adjacent streams and rivers as well as local site drainage. Procedures and guidance from the NRC and others are presented for PMP flooding analysis on river watersheds. The presentation is based on analysis performed for recent applications to the NRC as well as the NRC's independent PMP analyses that were preformed to evaluate the applications. Specific topics addressed are the spatial and temporal development of the PMP for a watershed, runoff analysis and calibration of runoff analysis, flood routing, combined events criteria, water level determination, and NRC independent analysis approach.

A two-dimensional embankment breach analysis was conducted to estimate the postulated worst case flood levels to support the combined operation and construction licensing of a nuclear power plant. A multi-dimensional hydrodynamic model, Delft3D-FLOW, was used to simulate flooding from an instantaneous breaching of the embankment of an on-site cooling reservoir with a surface area of about 7,000 acre (2,800 hectare) and an average height of 40 ft (12.2 m). The Delft3D-FLOW feature for solving rapidly varying flows ("Flooding scheme") was utilized for the analysis. The results capture the water level variation due to the initial flood wave impact on the safety-related power buildings and the subsequent quasi-steady state flooding conditions that prevail for a few minutes. Various tailwater conditions (including dry bed) were analyzed to determine the critical flood level to be used as the design basis for the safety related facilities of the nuclear power plant.

Termed the largest "recycling" project in Texas, the City of Dallas is currently developing a enhanced leachate recirculation (ELR) project at the McCommas Bluff Landfill (Landfill). As one of the largest municipal solid waste (MSW) landfills in the Country, it typically receives 7,000 tons of MSW per day and supports a 5-million cubic feet per day high-BTU landfill gas (LFG) processing facility. The landfill's enhanced waste degradation could result in the destruction of up to 40-percent of the in-situ waste volume; hence the largest "recycling" project. The City recently completed the permit stage for this project. In early 2008, the City will begin placement of waste in Cell 6, the first cell permitted for ELR. Installation and operation of the first lift of recirculation laterals and gas collectors will take place throughout 2008. Conceptual design factors include: 1 Bioreactor type (anaerobic, aerobic, or hybrid). 2 Leachate or added liquid pretreatment, storage, and delivery. 3 Liquid application methods. 4 Odor control. 5 Innovative LFG collection in wet waste. 6 Cover soils and liner design.

A problem associated with landfills is the production of leachate, caused by water infiltrating into the disposed waste material, and the migration of it from the landfill with various contaminants. The solution to this is to reduce infiltration, which reduces the leachate production. Vegetative covers are an attractive method in the arid regions using evapotranspiration to reduce the amount of water seeping into the landfill. In the tropics, where rainfall exceeds the potential evapotranspiration, runoff enhancing mechanisms can be used to minimize infiltration and leachate generation. An experimental landfill cover site with rain gutters placed as runoff enhancing mechanism had been established at the Marine Corps Base Hawaii in Kaneohe, Hawaii to monitor different components of the water balance in three different treatments — control, 20 % and 40 % coverage with gutters. A rain simulator was also used to augment the natural rain episodes to obtain a wider range of rainfall intensities. While both the 20% and 40% covered areas produced lower amounts of leachates than the control plot, the 40 % covered area did not produce the expected (lesser) amount of leachate. The gutters were more effective in high intensity rainfalls than in low intensity ones. These observations suggest that interception by vegetation overhanging into the gutters might have reduced runoff generation. The Hydrological Evaluation of Landfill Performance (HELP) model was used to study the leachate and the runoff generated. The simulated results overestimated the leachate generation in agreement with the understanding that daily averaging of rainfall should increase the leachate volume. Additional event based modeling are also under progress to look at the process in detail.

Soybean hulls are processed into soy flour in a method similar to paper mill production. During the process, the soybean hull wastewater (SHW) is discharged into an anaerobic lagoon and then into an aeration basin. From there, it passes to a facultative lagoon before discharge. Even after this conventional treatment, the SHW has extremely high amounts of Total Kjeldahl Nitrogen (TKN), Chemical Oxygen Demand (COD) and a high pH. We have developed an attached growth, packed-bed bioreactor (PBR) containing the white rot fungus (WRF), Phanerochaete chrysosporium. This fungus secretes enzymes that catalyze oxidation reactions that result in degradation of recalcitrant compounds such as PCB, PCP, and pesticides. Previous studies utilizing the fungus in a bioreactor found that it could decolorize a polymeric dye. We hypothesize that the WRF could degrade the SHW and reduce the TKN and COD. We also assessed the effectiveness of pH adjustment of the SHW before introduction into the bioreactor. The objectives were to evaluate the ability of P. chrysosporium grown in a PBR to degrade the SHW containing high concentrations of TKN and complex organic compounds and to investigate the effectiveness of pH adjustment of the SHW before treatment in the PBR. The WRF in the PBR was fed an N-limited media for 5 days before introduction of the SHW. The effluent was sampled daily and measure for TKN, COD and pH. The pH adjusted wastewater was recycled through the PBR and the effluent was sampled daily and measure for TKN, COD and pH. Within 48 hours, 63% of the TKN and 37% of the COD was degraded. The pH of the effluent increased steadily from an initial pH of 4.88 to 8.59 at 24 hours. Within 72 hours, the effluent pH was equal to the influent pH. At this point, degradation within the PBR ceased. Continuous adjustment of pH during recycling of the wastewater within the PBR resulted in an increase in the amount of TKN and COD degraded. Over 90% of the TKN and approximately 33% of the COD was removed during treatment within the PBR. The pH of the SHW in the PBR had a significant effect on fungal degradation. The reduction of COD was more sensitive to pH changes than the reduction of TKN. With the improved pH control in the PBR during recycling events, a greater amount of TKN and COD were removed from the wastewater. These positive results indicate that treatment of recalcitrant wastewater with the WRF deserves further investigation.

Facilities across North America are designing plants to meet stringent limit of technology (LOT) treatment for nitrogen removal. This is in response to the Chesapeake Bay Agreement, which will limit effluent total nitrogen to 3 mg/L. Of particular interest is the use of an alternate external carbon source to replace the most commonly used carbon, methanol. Replacing methanol with an alternate external carbon source for denitrification in the winter will be particularly important since methanol utilizer growth is stunted during colder temperatures. This study focuses on three external carbon sources: methanol, ethanol and acetate. The aim of this study was to obtain the specific denitrification rate (SDNR) of the substrates in two different contexts. Sequencing batch reactors (SBRs) were set up to acclimate carbon free biomass to the specified substrate while in-situ SDNRs were conducted concurrently. Once the biomass was acclimated to the corresponding substrate, a series of ex-situ SDNRs were performed using various biomass/substrate combinations. All experiments were conducted at 13°C. The results suggest that the SDNRs for acetate (32 mgNO₃-N/gVSS/hr) and ethanol (30 mgNO₃-N/gVSS/hr) are higher than that for methanol (9 mgNO₃-N/gVSS/hr). Ethanol acclimated biomass fed with acetate resulted in the highest SDNR of 26 mgNO₃-N/gVSS/hr.

In this paper the effect of the sulphate concentration on the performance of a three-stage anaerobic baffled packed-bed reactor (ABPR) was investigated. Synthetic wastewater (3000 mg COD/l) was used as the sole organic substrate. The 30 liters fixed-bed bioreactor filled with plastic packing and divided in three equal sections was used as the mABPR reactor. The unit was run at a hydraulic retention time (HRT) of 1 day and at temperature of 25° C. The results of this study showed that when COD/SO4^2– ratios were changed from 30 to 3 with increasing sulphate concentration from 100 to 1000 mg/l, COD removal slightly was decreased. Maximum COD and sulphate removal were 91 and 96%, respectively, where more than 50% of this removal occurred in first compartment in the whole experiment. Overall sulphate concentration had little effect on the efficiency of organic removal and the anaerobic reactor performed well under various conditions, tolerating high concentration of sulphate.

There has been increased recognition that the world faces serious challenges in terms of long-term economic growth, societal prosperity, and environmental protection. In particular, health problems resulting from environmental risks and a lack of economic resources in the developing world pose daunting challenges to the global scientific and engineering communities. Addressing these challenges through international research experiences integrated with sustainability and appropriate technology principles represents a significant and critical contribution to a more sustainable future. This paper describes a National Science Foundation-supported international research partnership that helps address sustainable development through increasing global access to adequate water and sanitation. The partnership consisted of seven undergraduate and graduate students from Michigan Technological University, six undergraduate environmental engineering students from Bolivian Technological University (UTB), and technical staff affiliated with a non-governmental organization, ACDI-VOCA (Agricultural Cooperative Development International and Volunteers in Overseas Cooperative Assistance). The Michigan Tech students were studying environmental engineering, civil engineering, mechanical engineering, and environmental policy. Wastewater treatment systems located in three small rural communities (Palos Blancos, Sapecho, and San Antonio) were studied. These three systems include: 1) a septic tank with anaerobic filter, 2) an Upflow Sludge Blanket Reactor with stabilizing lagoons, and 3) a stabilization-lagoon system respectively. Detailed water quality analyses were performed at each plant and performance was compared with the projected performance from the original design. System efficiency was evaluated in terms of cost, treatment effectiveness, and maintenance. Additionally, interviews with water committees were completed to determine what understanding of the system was conveyed when the technology was transferred from the design and construction stage to the community. Results showed that only two of three systems were functioning due to failure in operation, low capacity, insufficient funds for maintenance, system over-design, and the lack of knowledge base about the system from the community. Plant performance appears to be strongly influenced by the knowledge base and lack of funds for each water committee. Recommendations were made for greater ease in community ownership of constructed wastewater treatment systems. This collaborative research effort produced an intensive cultural exchange and inter-disciplinary collaboration demonstrating developing communities' reasons why systems under-perform.

This research describes an experimental technique which has been used to determine the efficiency of the USBF process in organic matter reduction and phosphorus removal. Continuous feeding of synthetic wastewater was used in different hydraulic retention times to access the optimized HRT according to the phosphate removal capacity of the USBF pilot and the sludge quality. HRTs varied from 16, 14, 12, 10, 8, 6 and 4 hours for the settling compartment, with the COD/P ratio remaining around 50, while the PO₄^3–-P concentration was about 20 mg/l. The experiments were performed at pH between 6.5–7.8 and at room temperature (i.e. 20±2 °C). The results of the experiments showed that the test system was efficient in removing COD and P in more than 85 percent of the cases for all of the tests after 20 days. The best results for P removal were obtained at the HRTs less than 8 hours while the Sludge Volume Index (SVI) was more than 150ml in lower HRTs as 6 and 4 hour. In the statistical analysis done to explain the results, it is revealed that with the differing parameters of P removal efficiency, SVI and the Total Suspended Solid (TSS), the optimized HRT for the Settling compartment is 10 hours.

A three-dimensional numerical model was developed for the proposed primary settling tank (PST) for the Calumet Water Reclamation Plant (CWRP) in Chicago, IL. The numerical model can deal with three-dimensional multi-phase turbulent flow. Two-fluid model is used to capture the behavior of the solid-water mixture. Hindered settling was modeled by an empirical exponential relationship between the settling velocity and the solids concentration. The sludge was modeled as a Bingham plastic with parameters estimated from experiments. During the design, the most important parameters are the tank's depth and diameter. These two parameters are also the controlling factors for the construction cost. Other parameters include the inlet/outlet structure, feed well depth/diameter, bottom slope, etc. The tank diameter is fixed due to the space restriction. The tank depth and feed well depth were analyzed by comparing different options. Once these two parameters were fixed, other parameters were fine tuned to optimize the performance of the tank. Due to the length of this paper, only the simulations for the tank depth and the feed well depth are introduced.

Traditionally, contact time of a chlorine contact tank (CCT) is determined by performing field tracer tests. This paper presents an alternative of using computational fluids dynamics (CFD) modeling to predict the contact time. This method is known as numerical tracer testing. Field tracer tests require maintaining constant flow through the CCT, chemical injection at the inlet, and continuous sampling. Typically three or more tests must be conducted at different flows to create flow-contact time curves. These requirements are difficult to meet in potable or wastewater treatment plants in operation; the tests are cumbersome and require significant operator effort. Numerical tracer testing facilitates the task without operation interruptions or complex set-ups. Numerical tracer testing was used for determining the contact time at the Irvine Ranch Water District's (IRWD) Michelson Water Reclamation Plant CCT in Irvine, California. The CCT is a two-million gallon, four-pass baffled tank capable of handling up to 20 mgd of tertiary filter effluent. CFD results were compared to field data obtained with a step-feed field tracer tests using lithium chloride. The comparison shows that CFD modeling is capable of accurately predicting contact times in the CCT. CFD modeling was used then to perform step-feed and slug-feed tracer test simulations at different flows in order to obtain T₁₀ and modal contact times. CFD modeling was also used for predicting flow patterns in the CCT. Results of CFD modeling, including flow streamlines, velocity contours and vectors, were used to improve velocity distribution and reduce solids deposition, short-circuiting and vortices with the inclusion of baffles. The study demonstrates that CFD modeling is a valuable modeling tool for the water and wastewater industry.

Within Australia water for use in concrete must be potable. However, ever increasing demands on water are depleting the available resources. Whilst it is currently thought that concrete properties are highly influenced by the water type used and its proportion in the concrete mix, there is little knowledge of the effects of different, alternative water sources used in concrete mix design. One such water source, recycled wash water is currently used by batch plants as mixing water for concrete. This comprehensive study of suitable water sources aimed to gain a better understanding of the current water reuse and recycle techniques and the subsequent characteristics of the wash water each produced. The quality of the waters collected was monitored with the standard Internal Readymix Variables such as SO₄^2–, Cl^–, TDS and others. Their influence, on fresh, hardening and hardened concrete properties was investigated by measuring the compression strength and shrinkage of individual concrete cylinders prepared with the use of these waters over a ten week period. The use of Principal Component Analysis indicated that the physical propoperties of concrete are unaffected by the different waters provided that the water quality was within the specified standard limits. A relative rank order of the water samples was obtained with the use of the PROMETHEE ranking chemometrics and this can be applied for comparative to future recycled water quality applications.

Many utilities are currently using drinking water sources impacted by wastewater discharge and others are planning for or implementing indirect potable reuse via groundwater recharge systems. The use of water sources impacted by wastewater has raised public concerns due to the presence of trace organic contaminants. Many wastewater-derived organic compounds are often present at extremely low concentrations and no standardized analytical methods are available. This study proposes that simple to measure surrogates (bulk parameters) and indicators (individual organic compounds) can be used together to assess the performance of soil aquifer treatment and membrane systems treating recycled water containing wastewater-derived organic contaminants. Potential surrogates and indicators were identified and validated in the field at full-scale soil-aquifer treatment and membrane systems.

The "Zero-Discharge" Wastewater Treatment System has been advocated for the scenic and/or historically preserving tourism spots. The Decentralized Wastewater Treatment (DWT) coupled with the Land Treatment Method has been found to be the most effective treatment system to achieve such historically unachievable "Zero-Discharge" dream. The DWT, normally also referred as aerobic onsite or clustered wastewater treatment system, is installed to provide efficient treatment for group of residential dwellings and businesses in sparsely distributed community. It has been reported that the performance of commercially manufactured DWT is adequate in some cases but its reliability is questionable. In reality, the roots of its lack of reliability, is caused by the inappropriate handling and disposal of treated effluent. The objective of this paper is to present an innovative sustainable design approach for DWT based on extended aeration principles and complete effluent utilization by land treatment. The integrated design approach, presented herein, has also incorporated the following considerations: environmental sustainability, protection against the contamination of surrounding environment, commercial viability, minimum maintainability, and the minimum amount of sludge production. Engineering design details for both DWT's with and without separate settling basin in compliance with the current regulatory requirements have been developed and will be presented. In order to illustrate the applicability of developed self-sustainable designs, real world examples will also be presented.

A method for pricing residential municipal water with increasing rate structures is developed and applied in this article. The method relies on the water-use functions for each block of a rate structure and on economic and water-supply data to produce a nonlinear programming problem whose objective function is the recovery of water-production costs. Maximum-water use, minimum-water use, cost-recovery, and price constraints were imposed on the objective function to complete the rate-design nonlinear programming problem, whose solution yields the block prices and water-meter charge of a water-rate structure. The water-pricing method is applied to a small municipality —on the order of 90000 residents— whose water-use functions were derived from data collected during the 1988–1991 California drought. The water-pricing method produced a rate structure that complies with specified constraints and recovers water-production costs, demonstrating that it is a useful tool for residential water pricing.

This paper describes a hydro-economic analysis of agricultural, environmental and urban water supply alternatives for years 2025 and 2080, in Baja California. Alternatives include idealized water markets, wastewater reuse, seawater desalination and infrastructural expansions. A network of the water system was built to considering hydrology, agricultural, environmental and urban demands, infrastructure, economic values of water and operating costs. Wastewater reuse with other projected infrastructure expansions are overall the most economically optima alternatives. Markets offer leverage and flexibility for the future urban needs for locations with the proper infrastructure. Worthwhile expansions include a larger aqueduct to convey Colorado River water to the west. At current water price and operating costs, seawater desalination is uneconomical. Wastewater reuse for restoration is also an economic source of instream flows, with institutional arrangements on a subsidized water price. Hydro-economic analysis is useful to better understand water-related issues in Baja California and provide a technical basis for developing and comparing long-term water management solutions.

Effective technology and approaches for reducing phosphorus concentration in the lake water are essential to control cyanobacterial bloom and lake eutrophication. This study investigated the effectiveness of the combined usage of ferrous iron (FeCl₂) and diatomite for the phosphorus removal. Several combinations of FeCl₂ and diatomite in various ratios were tested. Higher amounts of phosphorus were removed from water by the combined usage of FeCl₂ and diatomite than that by FeCl₂ alone. The optimum diatomite to FeCl₂ ratio resulting in the highest efficiency was 0.8. Alkalinity and pH of lake water treated with the combined usage of FeCl₂ and diatomite decreased less than that treated by FeCl₂. The higher P removal efficiency achieved by the combined usage of FeCl₂ and diatomite can be explained as that dissolved silica provided by diatomite was incorporated into the crystalline structure of iron oxide during the ferrous oxidation and thus silica-stabilized ferrihydrite was formed. Silica-stabilized ferrihydrite was an effective phosphorus adsorbent and long-term phosphorus sink. However, ferric oxide formed without dissolved silica was transformed into more crystalline ferric oxide and then phosphorus would be released back to the lake water during this transformation. Diatom growth was stimulated by the increased dissolved Fe and dissolved Si which was provided by diatomite. The stimulated diatom growth can further uptake phosphorus following the phosphorus adsorption by the silicate stabilized ferrihydrite. It was concluded that the combined usage of FeCl₂ and diatomite is an effective approach for improving the chemical precipitation of phosphorus by FeCl₂.

The Marin Municipal Water District (MMWD) Seawater Desalination Pilot Program was a successful year-long desalination pilot study of advanced pretreatment and SWRO technologies for desalting water from San Francisco Bay (Bay) from June 2005 to May 2006. Based on the favorable outcome of the pilot program, it was confirmed that seawater desalination can be a local, reliable drought-proof source of drinking water supply for Marin County, California. The MMWD SWRO Program provided preliminary design criteria for a full scale desalination facility, provided data to refine full-scale plant cost opinions, demonstrated the high quality of the desalinated water and facilitated essential environmental studies for a future full scale project. A primary objective of the pilot testing program was to compare the performance of high rejection seawater RO membranes with two different pretreatment alternatives: MF/UF and conventional pretreatment. The pilot program also included analytical testing of over 100 regulated and 500 non-regulated constituents in the Bay water and RO permeate, as well as an evaluation of second pass RO to meet MMWD's stringent finished water boron and sodium requirements. Environmental studies conducted in conjunction with the pilot testing included fish entrainment studies, bioassay studies and California Toxics Rule analysis of the brine discharge and toxicity analysis of the residuals from the pretreatment systems.

With the fast economy development in coastal regions, China, some water and soil environmental problems appear, such as that salt water fill in the soil where is fill-building fields, sea water invading into inland while groundwater decrease, and so on. In these areas, the eco-environmental conditions and underground constructions are impacted by the soil saline-alkali. This study presents the control measures of Coastal Saline-alkali Field Control, of which the main contents are as follows:(1) to understand the reasons of Saline-alkali formation, (2) to develop the control measures including: water conservancy, vegetation methods, biologic and chemical measures, etc. (3) to analyze the economic, social and environmental benefits generated by meliorating Saline-alkali soil. However, the relations between the soil salinization and the natural or human influence are not clear. What we need to do is to develop new desalination measures, such as making full use of rainwater during flood seasons, and carry on benefit recognition and quantitative evaluation for the benefit brought by meliorating Saline-alkali soil.

Maui is experiencing significant population growth in its most water-short areas in Central and South Maui. Recently, the feasibility of using desalination to provide alternative supplies to meet future needs has been studied. The Maui Department of Water Supply determined a 5-mgd brackish water Reverse Osmosis (RO) facility was feasible in Central Maui. A private developer is planning on a 1.5-mgd brackish water RO facility to meet potable water needs for a 670-acre, 1400-unit development in South Maui. For desalination projects, one of the toughest questions to answer is "What would you do with the concentrate?" For both projects, various concentrate management alternatives were evaluated including surface water discharge, disposal to sewer, evaporation ponds, subsurface injection, and land application. For the 5-mgd Central Maui facility, subsurface injection was determined to be the best option because of its simplicity, low cost, and ease of implementation. For the 1.5-mgd South Maui facility, land application through irrigation was determined to be the best option because of the relatively high quality concentrate and the opportunity to blend with other source waters (recycled water and brackish water) to meet a large irrigation demand (golf course).

Water Treatment Plants (WTP) have a key role in water supply with adequate quantity and quality in desired pressure condition. Sustainable performance of these systems is very important and quantifies the readiness of them especially in critical conditions. System readiness is one of the main issues that water users, stakeholders and decision makers of water resources consider in order to decrease the probable damages. In this paper, a methodology for assessment of a WTP performance has been proposed. This methodology quantifies the readiness of the system in different stages of plant's operation. For this purpose, three system operation indices including reliability, resiliency and vulnerability are considered. Due to the differences between the indices and especial characteristics of them, a hybrid index of them can be a good indicator of the system performance. In this study, the mentioned indices have been hybridized considering the importance of water shortages in system readiness evaluation utilizing Artificial Neural Networks (ANNs). In order to evaluate a WTP performance, the proposed hybrid index is developed. It is categorized into different levels for assessing the system readiness in critical conditions. The proposed methodology has been applied for a WTP in Tehran metropolitan area in Iran. The Results show that this algorithm can be effectively used for evaluation of the WTP performance.

Airlift reactors with a bubbly flow are commonly used to add oxygen to the hypolimnion of lakes. However, there is no reliable information on the gas transfer that will occur in a field-scale airlift reactor. Gas transfer experiments are conducted inside a deep bubble column/airlift reactor containing air and water with a maximum aerated water height of 23.4 meters and diameter of 1.06 meters. The effects of geometry and operating conditions on gas transfer are determined. A two-phase convection-dispersion model is fit to the DO measurements using the liquid film coefficient (K_L) as a fitting parameter. Sparger differences had a substantial effect upon K_L, and the gas transfer coefficient for the airlift reactor was four times that of the bubble column. Results are characterized using Sherwood, Reynolds and Bond numbers. A low Reynolds number exponent was found, indicating that K_L in a deep column tends towards a constant and is not highly dependent upon air discharge.

Potable water treatment is one of the most challenging and complex systems that municipalities need to deal with considering limited resources. The average age of continuously deteriorating Canadian water supply system was 36 years and that would require 3.1 billion dollar to bring the system at satisfactory level. Operators have little attention to plant infrastructure and equipment compared to water quality and day-to-day operational activities. Water treatment plant (WTP) includes several elements, such as tanks, basins and pumps. Essential condition parameters are selected including technical, physical, environmental, and operational aspects of WTP. Data on the WTP conditions are collected from experts and consultants in this domain. The targeted experts were operators, designers, consultants, regulators and researchers across Canada and few from abroad. To determine the condition index of a WTP element, value additive multi-attribute theory (MAUT) has been used where average weights and scores are considered. It is concluded that the average condition index for settling basin ranges from 9.6 (best scenarios) to 1.9 (worst scenarios) and from 9.6 to 3.4 for pumps of WTP. Analysis reveals that, for tank and basins, design and construction stage is the most important parameter to the WTP condition. On the contrary, operational parameter is the most important for pumps. The study also highlights durability issues and details in structural design as the most important parameters for future condition of tanks and basins. However, operation and maintenance practice are the most important parameters for pumps.

The nested models simulate flow and transport in the Lake Michigan coast around Milwaukee, have alongshore and cross-shore dimensions of 45.5 km and 12 km, and maximum depth of 25 m. The alignment of the open lake boundary is important because the boundary condition formulation may introduce perturbations when oblique velocities cross the boundary. Aligning the open boundary parallel to an isobath caused negligible perturbations. The models yielded a good reproduction of measured currents and an adequate reproduction of vertical temperature profiles. The alongshore currents are approximately ten times larger than the cross-shore currents. Local wind direction is an insufficient predictor of flow direction. The lake circulation pattern sometimes causes the flow near Milwaukee to split into counter-rotating eddies. Preliminary results of the transport model reveal that along-shore transport dominates over cross-shore transport and a complex transport pattern inside the Milwaukee Outer Harbor when the currents through the breakwater gaps change direction.

This paper presents the simulations of saline and turbid gravity currents using a subgrid model, which considers the effect of density stratification on the eddy viscosity. The saline gravity current simulated here is the intrusive current in a reservoir with two layers of quiescent fluids with different densities. The suspension fluid was stored initially in a lock; instantaneous opening of the lock gate initiated the gravity current that intruded in the middle of the ambient fluid layers. The internal subgrid scale structures of the density current are observed in the simulation. The numerical model has also been applied in the simulation of turbidity current over a mildly inclined surface. The turbidity current was generated by a constant discharge of a well-sorted sediment and water mixture into the reservoir. The sediment deposition and entrainment near the bottom are considered in the simulation. The vertical velocity profile, turbidity current intrusion speed, and sediment deposition are predicted reasonably well by the numerical model.

A coastal and estuarine model has been extensively validated by simulating morphodynamic responses to long-term hydrological conditions including typhoons, storm waves, winds, and river floods occurred in an estuary. The computed morphological changes over several years are in good agreement with the in situ bathymetry measurements. The numerical results also revealed complex flow patterns and morphological changes in the estuary, e.g., bank overflow and coastal inundation, erosion/deposition, as well as breaching of river mouth sand bar. These results are important to understanding of sediment transport and morphodynamic processes in the estuary especially due to storms, tides, and floods. This validated numerical model is, therefore, capable of assisting engineers and researchers to achieve better long-term coastal flood management and infrastructure design against various complex hydrological conditions in coasts and estuaries.

HEC-RAS is a one-dimensional steady or unsteady open channel flow model developed by the U.S. Army Corps Engineers' Hydrologic Engineering Center. It is probably the most widely used one-dimensional program in the world, and is used for a variety of applications, such as flood insurance and flood reduction studies, bridge hydraulics, stream restoration, and dam break analyses. While the HEC-RAS modeling system is well documented and general guidance on model applications and parameter selections is provided, modelers often do not understand the uncertainty or sensitivity associated with some model parameters. In addition, HEC-RAS is sometimes misapplied as modelers often do not understand the applicability of HEC-RAS. This paper presents a series of steady flow model examples to test the sensitivities of three key parameters or processes, including cross section spacing, expansion ratio, and lateral weir discharge coefficient. Using the model test results, practical guidance on model parameterization is provided. In addition, using an example application, cautions of using HEC-RAS results to interpret a two-dimensional floodplain are discussed.

Recently, many researchers revealed that the conventional approximate Riemann solvers are inadequate to deal with the real-life one-dimensional open channel flows because of problems such as unrealistic flow caused by numerical imbalance as well as inaccuracy in the solution of discharge when the channel has complex geometry and a hydraulic jump is present. To overcome these deficiencies, several new techniques have been proposed, including: (1) adopting the form of the Saint Venant equations which include only one source term representing driving forces; (2) using water surface level as one of the primitive variables; (3) defining discharge at interface and evaluating it according to the flux obtained by the HLL Riemann solver. In this paper, the performance of this new scheme is evaluated by means of two dam-break flow problems. The comparisons of computed results with analytic solutions and data measured from the physical model show that the scheme is capable of satisfactorily reproducing open channel flows with irregular geometry.

The dynamic nature of alluvial fans in arid and semi-arid environments offers numerous floodplain management challenges primarily due to unpredictability of flowpaths and delivery of significant sediment. Construction of levees on alluvial fans is one of the primary structural control measures utilized in historically successful "whole fan" floodplain management that address flood protection requirements. Levee design and hydraulic evaluation for alluvial fans are much different than similar applications for standard riverine locations. Corresponding requirements by FEMA in determining flood hazard definition for alluvial fan locations also complicate the issues. The primary design elements associated with levees which are unique for alluvial fans include (1) geometry and alignment, (2) embankment cross section and (3) armoring requirements. Geomorphic and flooding characteristics on an alluvial fan involve various sources of uncertainties that require the application of statistical procedures to evaluate flooding at a given point on the alluvial fan. Armoring of the levee face is an essential requirement to ensure successful operation and specific analysis must be applied to evaluate the vertical limits of the armoring, specifically toe-down depths, since scouring of the slope protection is one of the most common failure modes. The hydraulic evaluation must include the analyzes of potential alternative flowpaths, flow-impingement on the levee, degradation, deposition, sediment ramping, and maximum flooding depths from a variable and random flowpaths. This paper presents the previously described design considerations for the construction of guiding and confining levees on alluvial fans with detailed discussions on each topic.

The aim of this work is the interpolation of a mean flow stream from discreet data supplied by a Doppler velocimeter. This is why a precise flow modeling in needed to be implemented in a code designed for sewer net conduit. A 2D mesh is used to calculate 3D velocity flow. This work deals with the description of a Reynolds stress model for the numerical simulation of uniform 3D turbulent open-channel flows. The finite volume method is used for the numerical solution (with Matlab) of the flow equations and transport equations of the Reynolds stress components. First the k-ε model has been implanted to test the method but it is found that both production terms by anisotropy of Reynolds normal stress and by Reynolds shear stress contribute to the generation of secondary currents. The results presented here are the calculation for full section flow in a rectangular channel which is one step in the overall project. Last the velocity profile has been measured in a 20m long experimental channel to validate the code. There is a good agreement between first measurements and the results predicted.

Since the 1970's, diversion of Waller Creek flood flow has been a goal of the City of Austin to reduce the risk of flooding to businesses downstream of Waterloo Park (15^th Street), thereby encouraging planned development close to the creek and at the street level above. In 1999 the City of Austin selected a joint venture comprised of Espey Consultants, Inc. and Kellogg Brown & Root Services, Inc. (JV) to provide professional services for preliminary design, final design and construction management services for the proposed Waller Creek Flood Diversion Tunnel Project in downtown Austin, Texas. The project includes statistical analyses, hydrologic and hydraulic modeling and optimization, preliminary and final design and economic analyses. The estimated cost of the project exceeds $100 million and will be under construction in the fall of 2010. Construction will be complete in 2014. The project consists of a one-mile long, 22-foot diameter bypass tunnel, inlet and outlet structures, and side overflow weir diversion system. The inlet at Waterloo Park will divert approximately 85% of the 5.75 square mile watershed to the outlet at Lady Bird Lake. The side overflow weir system will divert stormwater flow from the lower portion (approximately 15%) of the watershed to the main flood control tunnel. Upon project completion, the 100-year flood event flow will be contained within the existing creek channel downstream of the inlet structure.

Organic pollutants in industrial coastal basins are generated from a number of sources including coastal effluents and loading/unloading offshore stations. Such pollutants may adversely affect the quality intakes of other strategic coastal facilities such as coastal thermal desalination plants. In United Arab Emirates, many of such desalination plants are located along one coast hosting refineries as well as other coastal facilities. Loading and unloading of oil tankers are also practiced from offshore stations. A number of organic pollutants are generated from these sources and can potentially threaten the quality of intake seawater of the nearby desalination plants. This paper presents the results of a fate transport modeling study for two selected organic pollutants; Phenol and PCB-180 (HeptachloroBiphenyl) in an industrial coastal basin located in United Arab Emirates. A number of parameters involved in the transport processes were determined from lab experiments while most other parameters were estimated from a numerical sensitivity study. The model results depict contour maps of dissolved concentrations of the two considered pollutants for three different wind conditions in summer and winter. The obtained results and observations constitute useful information for the desalination plants' operators due to the effect of intake quality on the quality of final distillate produced from thermal desalination processes.

A 3D hydrodynamic model is applied to simulate the radionuclide concentration distribution in typical receiving waters due to discharges from nuclear power plants. For a receiving reservoir, two representative hydrologic conditions are considered to produce water currents, namely, extremely low water level condition and normal water level condition. The boundary condition of the hole-outflow through the dam is well dealt with in reservoir modeling. The similar hydrologic conditions are also used for modeling the receiving river. Due to the much large river flow, effects of the half-life decay coefficient on the transport and fate of radionuclide discharge in receiving water are extensively examined. The effectiveness of the 3D model in producing the reservoir current patterns and hence the passive decay mass transport and fate is demonstrated.

In order to investigate the effects of nearshore discharges of water quality degrading substances and bacteria in coastal environments, models capable of predicting nearshore circulation due to local wave and tide conditions are required. One of the larger challenges to nearshore coastal modeling is accurately reproducing nearshore circulation due to wave action. Local wave action not only drives circulation through processes such as longshore transport and rip currents, but also contributes significantly to the mixing of water quality constituents. In the present work, a wave model was used to calculate radiation shear stresses and dissipation due to wave action. The shear stresses and dissipation were incorporated into a hydrodynamic model to force circulation in the nearshore environment. The model was applied to a site in Santa Cruz, CA where site specific current data was available. The model reproduces the nearshore current structure observed in the region and was used to study the transport of dredge disposal plumes in the region which could have deleterious effects on local beaches. This presentation will outline the nearshore circulation model development and application.

The Calgary Bow River Weir Project is intended to remove an existing safety hazard created by an ogee weir, while maintaining the weir's ability to divert water for irrigation and not increasing upstream flood levels. The river reach downstream of the weir will be transformed into a high water channel and a low water channel, each comprised of multiple pool-and-drop features to provide recreational opportunities for boaters and improve fish passage at the site. Computational fluid dynamics models were developed to evaluate hydraulic conditions of design modifications to HWC Drop #1. In this study, a volume-of-fluid (VOF) model was employed to predict the water surface profile and to assess whether a hydraulic jump would form downstream of the drop structure. The CFD models were validated by comparing CFD results with qualitative and quantitative data collected in the physical models. The comparisons indicated that the CFD models were able to correctly predict hydraulic jump formation immediately downstream of the weir for the existing design, and demonstrated satisfactory hydraulic conditions for the proposed design at flows at which boat passage is expected to occur. This study demonstrated that CFD modeling is a viable tool for predicting flows involving highly deformed water surfaces, such as those associated with hydraulic jumps.

The control of nutrients arising form Non-Point Source Pollution (NPSP) is difficult because the source areas can be hard to identify and typical treatment methods are infeasible due to the distributed nature. While restoration attempts may provide significant returns, they can be costly to implement and often are met with resistance. In order to quantify potential benefits, detailed hydrologic/water quality modeling of watersheds and the effects of Best Management Practices (BMP) is required. Extending model results beyond the range of calibration to model future conditions requires the use of physically based models that include the important processes that generate stream flow, material transport, uptake, loss, transformation, and recycling. In addition, given the complex nature of surface water and groundwater interaction, as well as the spatial nature of nutrient distribution, a distributed source transport model is needed to accurately account for the movement of water and nutrients through the various landscape media where more simplistic models are not applicable, or are homogeneous which is not appropriate for the heterogeneous nature of distributed sources. This paper will discuss the current research efforts and demonstrations taking place at the Engineer Research and Development Center (ERDC) as it relates to the nutrient sub-modules.

The present study is carry out to investigate the velocity fields and turbulence characteristics of the flow over permeable structures by channel experiment in low water level. Detailed measurements of the time-averaged velocity components, turbulence intensity components of permeable and solid structures are taken by the acoustic doppler velocimeter (ADV). The characteristic feature of porous medium is permeable, and the vertical distributions of time-averaged velocities above permeable structures are more uniform than solid structure due to the slip velocity at the fluid/porous interface. The turbulence intensity above structure with large porosity are slightly greater than small porosity structure, and the permeable structures have smaller turbulence intensity than solid structure around the structures. The results show that the porous medium reduces the turbulence intensity, and then reduce the scour to structures.

Development of a representative hydraulic model in flat coastal regions is often problematic. This can be complicated further if the study area is extensively crossed by elevated irrigation canals, roadways or railroad tracks that tend to impede or alter stormwater conveyance. In addition standard hydrologic assumptions, unit hydrograph shapes and hydraulic modeling techniques are often not applicable. This analysis will consider various hydrologic and hydraulic calibration parameters. Hydrologic calibration parameters considered will focus on time of concentration, antecedent moisture condition and peak rate factor. Hydraulic parameters will focus on Manning's "n" value and storage routing. A concern for floodplain managers in this region is that improving the efficiency of the drainage system would reduce storage volumes, thereby increasing peak discharge and causing additional flooding downstream of improvements. The presentation looks at this problem as encountered in the development of a Master Flood Protection Plan for Cameron County Drainage District #5. Drainage District #5 encompasses most of the City of Harlingen, and the Towns of Primera, Combes and Palm Valley. The District drains to the Arroyo Colorado, part of the Rio Grande floodway system and the Gulf Intracoastal Waterway.

Proper highway drainage is essential to ensure safe and comfortable conditions for the road users. The highway pavement and inlet geometry, especially cross slope and longitudinal slope and local depression and transition length, usually determine the highway surface drainage capacity. In this study, FLOW-3D is utilized to model the unsteady free-surface flow through curb opening inlets with different longitudinal and cross slopes. FLOW-3D, developed by the Flow Science, Inc., is a three-dimensional computational fluid dynamics software that can be utilized as "Virtual Lab" to study complex flow problems. FLOW-3D utilizes a true volume of fluid method (TruVOF) to compute free surface motion and the fractional area/volume obstacle representation (FAVOR) technique to model complex geometric regions. Flow characteristics near curb opening inlets are carefully examined. Inlet efficiency is determined from flow simulation results for the inlets with various longitudinal and cross slopes, especially for small slopes where laboratory tests were not able to be conducted. Inlet efficiencies for curb opening inlets with different transitional lengths before and after the inlet are examined using FLOW-3D simulation models. Simulation results are compared with laboratory observations with good agreement.

This paper discusses the results of an integrated hydrologic modelling to study potential adjustment to the established minimum flow and levels for lakes in Northwest Hillsborough County, Florida. The northwest area of Hillsborough County is characterized by numerous lakes and wetlands many of which are interconnected and managed via control structures or groundwater augmentations. Some lakes in the area are isolated and have much smaller contributing watershed and rarely reach their established minimum water levels. It is surmised that as a result of drainage alteration and land development some of these lakes are more impacted than others. In 2004–2005, challenges were made to the application of Southwest Florida Water Management District's Minimum Flow and Level rule (MFL) for Category 3 lakes (Raleigh, Rogers, and Starvation) and have, to some degree, raised the same issues related to land use/drainage alterations and lake water level impacts. The primary purpose of this study was to examine whether the drainage alteration and land development within the area have significantly affected the natural flow into the subject lakes, and determine whether such alterations warrant adjustment of the proposed lake minimum levels. To this end, an integrated surface and ground water model of the basin using the MIKE SHE software was developed to look into the inter-relationships among surface and ground water, water supply pumping in the adjacent well fields and drainage alterations in the past several decades. The study was conducted in three phases. Phase I consisted of data collection and digital terrain model (DTM) development for the proposed study area. During phase two, a complete watershed evaluation was performed, including hydrologic and hydraulic features inventory, surface water/subsurface water assessment, as well as a preliminary integrated modeling plan and approach. In phase III, the subject of this paper, an integrated hydrologic model of the site was developed to assist in the development of watershed management plan, with emphasis on the assessment of the potential impacts on lake water levels resulting from human activities such as drainage alteration and land development. To study the impacts, the calibrated model was used to simulate both the existing condition and historic landuses to compare water levels and develop strategies to lessen the impacts on the lake water levels.

The paper examines the effectiveness of prevalent USBR type VI models and proposes new shorter and efficient designs by means of laboratory experimentation. The models are tested on 4cm x 4cm square opening (d = 4cm) with an erodible material and a constant run time for inflow Froude no Fr = 6.83 with a diverging side walls at a slope of 1 V:0.75 H up to a length of 3.5d. A non-dimensional number called as performance number has been used as for comparison of performance of the models. Several appurtenances various shapes and sizes like splitter block, impact wall, intermediate sill, and end sills are tested in the laboratory. It has been found that this special pentagonal shaped block quite is helpful in spreading the jet of water in a shorter length, resulting into better and more energy dissipation. It was found that the length of energy dissipator models can be reduced by more than 15% as compared to USBR impact type VI energy dissipator model without sacrificing the performance.

A practical application of a three-dimensional (3D) computational fluid dynamics (CFD) model to optimize the design of a storage reservoir for its use as a clearwell is presented in this paper. A computational grid of the 20 million gallon (MG) reservoir, incorporating 285 columns supporting the roof, was created from existing design drawings. Initial model simulations indicated poor mixing and contact time, with T₁₀/T ratio of about 0.2, where T₁₀ is the tenth percentile of the hydraulic residence time, T. Therefore, various baffle arrangements were investigated to increase the T₁₀/T ratio to 0.72 and minimize the cost associated with retrofitting the reservoir with baffles. These duel considerations resulted in an unconventional design of the clearwell with an estimated cost saving of 45 percent. The paper analyzes the computed circulation patterns to identify the causes of significantly different hydraulic and mass transport characteristics of the reservoir, with and without columns, and the proposed design incorporating baffles.

Baffles are often used to retrofit culverts to aid in fish passage. The objective of this experimental investigation was to compare the turbulent flow structure inside a full-scale spiral corrugated culvert fitted with sloped- and slotted-weir baffles to available turbulence descriptions for non-baffled culverts. Velocity measurements were taken in a 1.83 m diameter, 12.2 m long corrugated metal culvert fitted with sloped- and slotted-weir baffles using a Sontek Micro-acoustic Doppler velocimeter for flow rates of 0.043, 0.085, 0.113, and 0.198 m³/s and culvert slopes of 1.14, 3.00, and 4.33%. Results showed there were only minor differences in the turbulent flow structure created by each baffle type. The most significant differences included higher lateral turbulent intensities on the edges of the jet created by the slotted-weir baffles, and higher turbulent kinetic energies on the left side of the culvert (looking downstream) caused by the sloped-weir baffles. Downstream from a slotted-weir baffle, a reduced velocity and streamwise turbulent intensity zone was found near the left edge of the flow that was similar to that found in the bare culvert. The sloped-weir baffles produced a less pronounced zone near the right edge of the flow.

Quality mesh generation for complex computational geometries still remains a challenging step in Computational Fluids Dynamics (CFD) analysis. This paper presents a method for 2D smooth mesh generation in geometrically complex domains where the local orthogonal conditions may result in skewed or overlapping mesh which is generally acceptable in numerical simulation. In the proposed method, two exponential parameters are introduced into the RL (Ryskin and Leal) orthogonal mesh generation system to control the distortion functions (orthogonal conditions). These parameters are adjustable and can be either user-specified or automatically evaluated by the smoothness conditions. With the relaxed orthogonal conditions, nearly orthogonal but smooth mesh is achieved in complex geometries. Examples and applications are also investigated in this paper.

The method of characteristics (MOC) in the context of finite element method was applied to simulate two-dimensional (2D) shallow water equations for overland flows. Many researchers have pointed out the advantage of MOC in solving two-dimensional shallow water hyperbolic equations having wave-like solutions. At the same time, they considered MOC for two-dimensional overland flow being non-tractable on complex topography and boundaries. For two-dimensional overland flows, finite element methods are very flexible in dealing with complex boundaries. The intrinsic difficulty in implementing MOC for 2D overland flows is that there are infinite numbers of wave characteristics in 2D problems, although only two independent wave directions are needed for a well-posed solution to the characteristic equations. We have implemented a numerical scheme that attempts to diagonalize the characteristic equations based on pressure and velocity gradient relationship. This diagonalization scheme was evaluated by comparison with other choice of wave characteristic directions in the literature. The circular dam break problem was solved with different selections of wave characteristic directions and the performance of each selection was evaluated based on accuracy and numerical stability. Finally, a 2D overland flow problem over complex topography in a wetland setting with very mild slope was solved with the diagonalization scheme along with other wave-selection directions to demonstrate its applicability.

Development of two-dimensional (2D) hydrodynamic model to simulate the propagation of long waves in a domain with sloping boundaries is presented in this paper. This study adopts the finite-volume method to solve hyperbolic shallow water equations and model various wave run-up problems. Godunov type HLL approximate Riemann solver is combined with divergence form of the bed slope to be able to simulate waves on irregular topography. The surface gradient method is used to have a well balanced scheme that the numerical errors can be removed. The accuracy is second order in space and time. The computational domain is constructed with unstructured triangular cells. The developed model, which is capable of simulating flow over dry and irregular domain, is run for dam break wave over a sloped bottom, tidal wave onto a sloped beach and solitary wave around a conical island. The experimental and numerical results published are used to verify the stability and accuracy of the model.

The four-point implicit scheme has long been applied in hydraulic modeling to solve the one-dimensional Saint Venant equations. Because of the advantages of numerical stability and efficiency, it has become the most widely adopted scheme for the simulation of unsteady open channel flows. In this paper, the scheme is re-analyzed using the viewpoint of the finite volume method. It is found that the mass conservation is defected at the inflow boundary if the parameter θ is chosen not equal to 0.5. The reason for this error is that the input flow in the model is discretized using the parameter θ and is different from the expected value. However, in practical applications θ > 0.5 is always used to maintain the unconditional numerical stability. Therefore the mass imbalance at boundaries introduces error to most cases. The error can be introduced either from the upstream boundary or from lateral inflow boundaries. The effect of this error is not serious when the modeling time step is very small or the inflow changes very slowly with time, which are generally not satisfied for actual highly unsteady flow simulations. Potential solutions for this issue are investigated and it is found that the only sound approach is to modify the scheme at the boundary.

The hydrodynamic variation process of the river flow in the reservoir of the Three Gorges Project was simulated by using the software Mike 11 based on the hydrological observation data from 2002 to 2003. According to the growth status of spawns or fries captured at the Yunyang Gauge Station, Chongqing city, the spawning sites of different kinds of Chinese carps can be determined by the flow distance based on the hydrodynamic calculation results. The accuracy of the spawning sites determined by this method is much better than those calculated according to the averaged velocity of the river. The uncertainty of this method is also discussed.

Over the past 50 years, there has been a well-documented collapse in white sturgeon recruitment in the Kootenai River, and white sturgeon has been listed as an endangered species since 1994. Libby Dam, constructed along the Kootenai River in northwest Montana, started operation in 1974, which is believed to be the last successful year for white sturgeon recruitment. Lack of appropriate spawning substrate is thought to be a primary factor responsible for white sturgeon population recruitment failure. White sturgeon are broadcast spawners that release adhesive, negatively buoyant eggs that sink to the riverbed. Three- to six-foot sand waves (or dunes) now exist in the reach where spawning occurs. Available information suggests that suffocation and high egg mortality occur where the bed is composed of shifting sand substrate. A Substrate Enhancement Pilot Project Implementation Plan was developed by the Seattle District, U.S. Army Corps of Engineers, to test the effectiveness of various types of artificial substrate for improving spawning success in the reach downstream of Libby Dam. 1:20 Froude-scale physical modeling of different artificial substrate designs was conducted at the Colorado State University Hydraulics Laboratory. This investigation involved three separate tests of rock riprap placed as a mass on the riverbed that projected above the effects of the sand waves. This paper presents an analysis of the flow velocities and turbulent Reynolds stresses that developed over the surface of each artificial substrate. In addition, an evaluation of the effectiveness of each substrate to trap and retain sturgeon eggs is presented.

Ecohydrological modeling of food webs can be a useful tool in stream/river health assessment, restoration, and management by providing insight into the long-term dynamics of biota. Conventional food web models are mostly limited to lake or marine ecosystems. In contrast to these models, stream ecosystem models need to capture the response associated with shorter residence times as well as the impacts of natural (hydrology, geomorphology, etc.) and anthropogenic (building dams and reservoirs, industrial pollution, etc.) drivers. Further, the benthic and non-benthic zones of streams/rivers have different physical, chemical and biological compositions. To investigate hydrologic drivers, along with other environmental and geomorphologic constraints, dimensional and non-dimensional food web models have been developed to evaluate ecosystem dynamics of the benthic and non-benthic zones of streams and rivers. Insights gained from these applications can be used to critique different food web modeling approaches and recommend an appropriate model for a given stream ecosystem.

This study presents the numerical predictions on the detailed hydrodynamic and habitat quality characteristics of riparian vegetation by using a depth-averaged two-dimensional flow model. The model solves the depth-averaged Reynolds Averaged Navier-Stokes Equation. The vegetative effect is considered by a drag force exerted by the flow on the vegetation, resulting in extra source terms included in the momentum equations. Simulated results of flows in a rectangular and a compound channel with vegetation along one side are coincided with the previous experimental data. Furthermore, the model is used to simulate the cutting management of riparian vegetation. Five different scenarios are proposed in this study, including original, as well as cutting along main-channel side, cutting along bank side, alternative cutting and reducing vegetative density. The influence of the proposed scenarios on hydrodynamic behaviors is investigated in a rectangular channel. Simulated results suggest that cutting along the main-channel side is the most effectively scenario among others in reducing the water depths and flow velocities of the original one.

The salmonids, salmon and trout, are economically and socially important fishes that require consideration and protection when roads are constructed and maintained within their ranges. Over the courses of their lives both resident and anadromous salmonids require a variety of aquatic habitats. It is well established that that these fishes need to have efficient access among streams in addition to efficient access to different habitats within streams to maintain viable populations. Barriers may either physically block movement or impose excessive energy costs on movement, thereby preventing or seriously impeding access to necessary habitats and affecting population sizes. Insuring fish passage at highway stream crossings is a key component of salmonid conservation and restoration efforts. Thus, the identification, prioritization, and treatment of migration barriers is a vital step towards recovering salmonid populations by restoring ecological connectivity.

Kootenai River White Sturgeon has become endangered because of its inability to successfully spawn. The sandy riverbed where the sturgeon currently spawn is considered an unsuitable spawning habitat. Successful sturgeon spawning locations in the Columbia and Snake rivers have cobble and boulder bed material. The Seattle District, U.S. Army Corps of Engineers has supported a series of physical model studies conducted by Colorado State University to evaluate artificial rock habitat structures that could be built in the Kootenai River to improve sturgeon spawning conditions. The study has focused on what type of structure would provide suitable spawning habitat and be sustainable in the sandy river environment. The three phase study has evaluated alternative sizes shapes, materials, spawning performance and sustainability.

Hydrodynamic and sediment transport models are useful engineering tools for predicting flood flow. Many models such as HEC-RAS, HEC-6, IALLUVIAL, SRH-1D were developed for perennial rivers, and may not be suitable to ephemeral rivers in arid and semi-arid regions. This paper outlines a comparison study that examined the water surface and bed elevations of a flood event exceeding 100-year flood in the Rillito River at Tucson, Arizona. The result of IALLUVIAL2, HEC-RAS and GSTAR1D models were compared with field survey data. Results showed that IALLUVIAL2, which cannot compute bridge effects, predicted a flood similar to that of the more commonly used HEC-RAS model, which take bridges into account. Both models underestimated the flooding by about 2 to 4 feet, but accurately predicted the progression of each flood flow. This study also found the most appropriate sediment transport and roughness equations for this particular river are Laursen sediment equation and Manning's relation. The results indicated the need of an appropriate model for predicting flood flows in ephemeral streams for water resource managers, engineers, and urban planners.

The Chicago Waterways System (CWS) is very complex and a complete understanding of the flow and water quality phenomena is not possible with current modeling tools. Among many interesting aspects, bi-directional flows have been observed in the Main Branch of Chicago River (MBCR) during winter time. Instead of flowing downstream into the South Branch (SB), part of the water from North Branch (NB), which usually carries runoff from a 100 square mile watershed and treated municipal sewage effluent released by the North Side Water Reclamation Plan (WRP), might flows into MBCR. This will have a huge impact on the water quality in MBCR, where the downtown Chicago is located. Physical model and field measurements of the CWS have been done to investigate the possible cause. Through these previous studies, density current has been identified as one of the main cause. A preliminary three dimensional numerical model also has been used in University of Illinois at Urbana and Champaign (UIUC) to simulate the density current. Although the bi-directional flow phenomena have been reproduced in the 3D model, the flow conditions are simplified and only very short period of time is simulated. In this paper, a three-dimensional environmental fluid dynamics code (EFDC) is used to simulate the flow in the Chicago River system (including NB, SB, and MBCR). EFDC is a public domain code which is supported by the Environmental Protection Agency (EPA) and has been widely used in many rivers and estuaries. It uses stretched or sigma vertical coordinate and Cartesian or curvilinear, orthogonal horizontal coordinate. Three-dimensional, hydrostatic, free surface, and turbulent flow equations are solved. Water quality models (such as sediment, temperature, toxics, dissolved oxygen, and biological oxygen demand) are also implemented. For this paper, the EFDC code is modified to simulate only the density current in CWS mainly due to the dissolved particles. The tests cases used in this paper are from the physical model work done in the hydrosystems lab in UIUC. The numerical model is validated and tested against the experiments. Good results have been achieved. More numerical simulations will be done to expand the parameter space. Water quality models will be activated in the future to see the environmental impact of different management strategies.

Bottomless arch culverts are employed as ecological passageways at road crossings. Such culverts are commonly used for fish passage as the adjacent natural channel reaches can be simulated and habitat barriers minimized (i.e. high base flow velocities, perched culvert outlets, etc). Though they have been developed to be environmentally sensitive, there is limited understanding of the hydraulic characteristics of bottomless arch culverts. To provide some design guidance specific to streambed stability in culverts, a streambed stability study was conducted using a smooth walled, 0.61-m (2-ft) diameter circular bottomless arch culvert and featured four different streambed armoring materials with the d₅₀ ranging in size from 6.75-mm to 37.3-mm. Several culvert entrance configurations were tested with headwater depths ranging from unsubmerged to submerged inlet conditions. Experimental data were used to evaluate eight published riprap stone-sizing stability relationships for potential applicability to streambed stability design in bottomless arch culverts.

An experiment was conducted in a laboratory flume at the St. Anthony Falls Laboratory, University of Minnesota, to study the sorting of mixed grain sized sediments around a spur dike in a flat-bed open channel. The flow field was measured by using a micro-acoustic Doppler velocimeter (ADV). Time histories for velocities in all three spatial directions were recorded at the upstream and downstream cross sections near the dike. Results showed that two counter-rotating, secondary flow cells originated at the dike: one cell resided in the recirculation zone and grew gradually toward downstream, and the other remained in the contracted primary flow zone, decaying as it transported downstream. These measurements illustrated spatial distributions of time-averaged velocity, turbulent Reynolds stresses, and mean and turbulent kinetic energy at the neighborhood around the dike. During sediment experiments, 15cm-thick well-sorted sediment mixture was placed on channel bed. A constant flow was discharged at the upstream until a scour hole was fully developed near the dike. Sediment size distribution at the scour hole showed sediment sorting closely related to turbulent flow field around the dike. The sorting of sediment mixture primarily attributed to the turbulent Reynolds stress, which is three times as large as the mean shear stress of incoming flow. For uniformly sized material, the scouring hole will evolve to a maximum depth until the Reynolds stresses are smaller than the critical shear stresses of a single grain-sized material. In the case of non-uniform material, the surface of scour hole was armored with sediment coarser than the substrate material, so that the scour hole will not be as deep as the one formed in a mobile bed of uniform bed material.

Culverts throughout the country are approaching or are past their original design lives. These `baby boomer' culverts will need to be repaired, rehabilitated, or replaced. Because entire culvert replacement is so expensive and intrusive, alternate measures to extend the culvert project life are growing increasingly popular. One such method is slip lining, where a `sleeve' is installed within an existing culvert barrel and stabilized. Plastic pipe sleeves are very popular for slip lining primarily because the plastic material's lower Manning's roughness value allows for the culvert capacity to be maintained despite a reduction in culvert size. Unfortunately, the reduced friction within the barrel can create a barrier to fish passage due to increased water velocities. The increased velocities also cause greater outlet scour which can result in further obstacles to fish passage. These new fish barriers can greatly affect aquatic ecosystems by limiting the access that fish have to smaller tributaries used for spawning and rearing—access that is critical to the life-cycles of many fish. It is suggested that mitigation of the increased velocities should go hand-in-hand with slip lined culvert design projects where fish passage (present or future) is to be considered. Can the demand for hydraulic capacity as well as the demand for fish passage be satisfied? To this point, there has been very limited experience in providing for fish passage through slip lined culverts. Research and reviews of current methods, as well as development of new design methods are still in progress.

Stream enhancement in Oregon is primarily focused on improving fish passage conditions. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal require fish passage designers to become more cognizant of hydraulic conditions over a range of flows to avoid expensive structural failure of hydraulic structures. These hydraulic structures may include culverts, bridges or roughened channels. Roughened channels are man-made stream channels utilized for retrofitting a hydraulic structure for fish passage when an existing hydraulic structure is structurally sound but deemed inadequate for fish movement through the passage. A variety of methods are utilized for the design of fish passages such as no impedance, geomorphic simulation, hydraulic simulation and hydraulic design. Mixtures of materials are used to construct the bed of roughened channels from fines such as sand, silt and gravel to coarse elements like cobble and boulders. Fines are a critical element in limiting permeability of the constructed bed thus keeping stream flow concentrated in the roughened channel during low flow periods. Our study focuses on the tendency for structural failure in roughened channels. The study goals are to determine the significant hydraulic design factors affecting the success or failure of roughened channels, particularly the loss of fines from the channel structure by examining actual fish passages in the region. Improving fish passages to enhance fish movement through the passage is a priority for government agencies such as Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC) who have to use less funding more effectively.

The diatom Didymosphenia geminata ("Didymo") forms thick and dense mats under low-nutrient and high-shear conditions. To investigate the effects of Didymo on open-channel hydraulics, we collected cobbles covered with Didymo mats from the Waitaki River, Canterbury, New Zealand. The cobbles were then emplaced in a recirculating flume and the system hydraulics were observed under several imposed flow rates. Following these measurements, the Didymo mats were removed from the cobbles, and the measurements were repeated over the bare cobbles. The mats overlapped and bridged gaps between cobbles, and thus were expected to reduce form drag. However, shear velocities and friction factors increased when Didymo mats were present, indicating that Didymo-covered beds are hydraulically rougher than the cobble beds despite the fact that the cobble surface is smoothed by the presence of the mats. We conclude that the mats introduce an additional roughness scale, and that their surface is much rougher than the bare stones. This conclusion is supported by direct visual observations of the mat morphology.

As part of a comprehensive program to enhance juvenile fish passage at McNary Lock and Dam to improve the survival of downstream migrating juvenile salmonids, the Walla Walla District is performing an investigation to develop benefits and costs for different alternatives for a permanent installation of a surface passage route at McNary Dam on the Columbia River. The desirable result will be development of a permanent installation that provides the greatest opportunity for improving downstream migration with fewer impacts on power generation, total dissolved gas levels, upstream migrants, navigation system, and the ability to pass flood flows. The surface bypass technology being implemented on the lower Snake River projects is to draw water from the surface using an elevated spillway crest located in a spillway bay. Utilizing a conventional spillway bay has inherit problems of using a spillway and stilling basin that were designed for efficiently passing a high volume of water and dissipating the associated energy. A promising alternative is a centerdam surface bypass (CSB) concept that utilizes an existing non-overflow section of the dam located between the powerhouse and the spillway. The purpose of this paper is to present the opportunities and benefits from developing a flume specific for fish passage that also has the potential of improving the overall objectives for operating McNary Dam. The primary, unique feature is to supply water under the high flow jet that is moving at a high velocity as it enters the tailrace. The feature almost eliminates the undesirable flow entrainment, high-shear zone, and re-circulating eddies in the tailrace that is typical of a high flow bypass.

The Rio Grande Silvery Minnow (RGSM) is an endangered species found in the Middle Rio Grande River in New Mexico. RGSM were historically abundant throughout the Rio Grande Basin, but now only occur downstream of Cochiti Dam to the tailwater of Elephant Butte Reservoir (designated as critical habitat). The decline of this species is primarily attributed to hydrologic manipulations caused by extensive diversions and impoundments. Further habitat degradation has resulted from stream channelization, loss of floodplain connectivity, invasive species, and watershed and riparian degradation. The primary objective of this study was to develop a habitat evaluation model driven by a two-dimensional hydrodynamic model and to apply the model to the Rio Grande Silvery Minnow in order to evaluate habitat suitability under unsteady flow conditions. An emphasis was placed on the availability and fragmentation of overbank habitats. The model results revealed high variability in habitat abundance and patchiness as a function of streamflow. Also, the quantity and connectivity of habitat was substantially different during the rising limb of an unsteady hydrograph when compared with the receding limb. The results demonstrate that this modeling technique provides valuable information for evaluating RGSM habitat and for targeting restoration sites on the Middle Rio Grande.

A 3-D hydrodynamic and heat transport computer modeling study was conducted in support of the intake and outfall design of a once-through circulating water system for a new 4 x 350 MW thermal power plant located on the coast of ****, Libya. Thermal recirculation at the proposed intake due to the new and existing discharges was examined with the 3-D model developed using the modeling software Delft3D-FLOW. The thermal impact of the proposed discharge on the intake of an existing power plant was also assessed. The site-specific 3-D hydrodynamic and heat transport model was developed and calibrated using field measurements of currents, water levels and temperatures. Proposed discharge and intake design locations were tested and found to satisfy the maximum water temperature increase criteria.

The use of two-dimensional hydraulic models for assistance in understanding of Upper Columbia Basin Streams was applied on the Upper Methow River located in Washington State. The Upper Columbia Spring Chinook Salmon, Steelhead and Bull Trout Recovery Plan (UCSRB, 2007) identified potential restoration strategies for basins in the upper Columbia. The UCSRB recovery plan recommended additional research to identify locations for preservation and restoration and also recommended additional examination of fluvial geomorphic processes to assess how processes affect habitat creation and loss. Identifying fluvial processes for existing and future conditions was applied to understand channel complexity for side channel and floodplain connectivity and for in-channel habitat. The SRH-2D (Sediment and River Hydraulics Two-dimensional) model was applied to a reach in the Upper Methow to determine existing and future channel processes. Application of the model enhanced understanding of channel processes and floodplain and side channel connectivity to help identify potential restoration and preservation projects. The model was able to provide quantitative results for bankfull and higher flows that provide indicators of channel and floodplain function, particularly when combined with geomorphic mapping and biological analysis from a multi-disciplined technical team.

A two phase model based on mechanistic principles capable of predicting water entrainment, gas volume fraction, bubble size and total dissolved gas (TDG) concentration in hydropower installations is presented. The model uses a Reynolds stress model accounting for the attenuation of the normal fluctuations at the free surface to capture the anisotropic turbulence structure and water entrainment observed in the spillway surface jets. A modified bubble-induced turbulence term is extended for the Reynolds stress components to account for suppression and production of turbulence by the bubbles. A bubble number density transport equation is used to predict the bubble size, which can change due to mass transfer and pressure. The TDG is calculated with a two-phase transport equation in which the source is the bubble/liquid mass transfer, function of the gas volume fraction and bubble size. Quantitative agreement between predictions and field data for the TDG and velocities in the stilling basin of Wanapum Dam is obtained. Numerical results of the hydrodynamics and TDG for two different operational conditions are presented discussed.

A hydraulic jump is the rapid transition from a high-velocity to a low-velocity open channel flow. It is characterized by strong turbulence and air bubble entrainment. Detailed air-water flow properties were measured in hydraulic jumps with partially-developed inflow conditions. The present data set together with the earlier data of Chanson (2006) yielded similar experiments conducted with identical inflow Froude numbers but Reynolds numbers between 24,000 and 98,000. The comparative results showed some drastic scale effects in the smaller hydraulic jumps in terms of void fraction and bubble count rate distributions. The present comparative analysis demonstrated quantitatively that dynamic similarity of two-phase flows in hydraulic jumps cannot be achieved with a Froude similitude. In experimental facilities with Reynolds numbers up to 10⁵, some viscous scale effects were observed in terms of the rate of entrained air and air-water interfacial area.

The hydraulics of side-channel spillways can be complex due to numerous potential flow regimes at the varying flow rates, energy losses from a wide variety of physical conditions, and the complexities associated with spatially varied flow with increasing discharge within the side channel. The analysis can become even more complex in the event that water levels in the side-channel begin to cause tailwater impacts or full submergence of the upstream spillway. Lake Skinner is owned and operated by the Metropolitan Water District of Southern California (Metropolitan) and this existing dam spillway utilizes a unique side-channel configuration that includes all of the above mentioned complexities. When originally designed in the 1960s, a reduced scale physical model of the ultimate spillway configuration was constructed and utilized along with mathematical computer models to predict how the spillway would operate under various flow conditions. Since the dam was constructed 40 years ago, the upstream watershed has realized changes in land use resulting in potential changes to the drainage basin runoff characteristics. In 2006, Metropolitan began to investigate if these changes to the drainage basin could affect the adequacy of the Lake Skinner dam spillway and retained Black & Veatch hydraulic engineers and hydrologists to perform the evaluation. Although the reduced scale physical model and mathematical computer model from the original design where not available, reports documenting the past findings were located. Utilizing the documented characteristics of the spillway as calibration data, modern day computer tools were utilized to construct a computer model of the complex spillway system. The computer modeling included the use of the Hinds side-channel spillway equation, the U.S. Army Corps of Engineers HEC-RAS and HEC-HMS modeling tools, and ogee spillway evaluations procedures from the U.S. Bureau of Reclamation's Design of Small Dams (1987). A Visual Basic Program integrated with an Excel Spreadsheet was developed to link the input and output variables of the various modeling packages and to perform logical iterations as required to converge on realistic results.

Recent activities in the design of reservoirs in coastal regions have pointed out the challenges of applying coastal engineering to inland reservoirs. And the impact of the interpretation of alternative methods can be MAJOR! Analysis on one project showed a cost impact on the order of $20 million using the same basic wind and rainfall design criteria, but alternative methodologies. How can that be? It is easier to understand when the design is for shallow reservoirs with large surface areas and long impoundment perimeters. One reservoir covered a surface area of 17,000 acres with a fully encircling embankment dam 20+ miles in length. In south Florida, subject to powerful hurricanes, embankment freeboard is a major cost component of any dam. The complex nature of coastal hydraulics has historically been evaluated using such tools as the Shore Protection Manual (SPM), Coastal Engineering Manual (CEM), and numerical wave models such as STWAVE. Due to the importance of freeboard design, a detailed effort was made to compare the alternative methodologies. Wave heights were determined using equations (CEM/SPM) and modeling (STWAVE). Wave runup and overwash were evaluated using numerical methods from the SPM, CEM, Technical Advisory Committee on Flood Defense (TACFD) guidance, and the computer program ACES. Wave heights, runup, and overwash can be determined using different sources in series, but not always with the consistency necessary for accurate results. When terminology and formulas become mixed between different references, a thorough understanding of the fundamental principals and formulas is essential. This paper will emphasize understanding the basis of the formula or methodology for correct application. Numerical results are presented in comparative tables as well as recommendations. This paper should be of interest to all those involved in the design, review, or re-evaluation of freeboard for dams.

Design flow requirements for both new and existing dams have increased over the past 30 years due (in part) to a series of dam failures caused by embankment overtopping. Increased spillway design flow requirements often require the renovation and re-design of the spillway crest for increased discharge without increasing reservoir pool elevation. Mitered ogee crests can be a viable alternative to the use of traditional ogee crests and to replacing broad crested weirs for increasing the discharge capacity of an existing spillway. Although the use of a traditional ogee crest would be the optimum design for increasing discharge, the use of a mitered crest would be simpler and more economical to construct than the profile of a traditional ogee crest. The application of a mitered ogee crest with a stair-stepped spillway is the subject of the following paper. Currently, there is little research available regarding the design of a mitered ogee crest. This paper discusses the discharge capacity of a mitered ogee crest and its application to stair-stepped spillways. A comparison of the performance and capacity of a stair-stepped spillway is made to the design of a traditional ogee crest (Army Corps of Engineers design specifications) and to the design of a broad crested weir. This paper is based on the 1:20 scale sectional and the 1:40 scale spillway physical models of the Gilboa Stair-Stepped Overflow Spillway, conducted at the Utah Water Research Laboratory, Utah State University. The analysis and comparison of the three types (traditional ogee, mitered ogee, and broad crested weir) of crest designs involved measuring discharge capacities and crest pressures. Each crest was tested for a variety of headwater conditions resulting in a series of rating curves for the assessment of three types of crest designs. Results are also presented in the form of discharge coefficient versus total reservoir head. The performance of the stair-steps of the spillway was evaluated for energy dissipation, cavitation, and flow interaction with the spillway steps. Analysis indicates that the mitered ogee crest performed considerably well when compared to the traditional ogee crest design. The mitered ogee crest produces 93% of the flow capacity of the traditional ogee crest while the broad crested weir design passed only 72% as much discharge as that of the traditional ogee crest. Therefore, retrofitting the crest of a stair-stepped spillway with a mitered ogee crest design is a very viable option. However, the spillway transition from the crest to the stair-stepped spillway is also an important flow performance consideration for all three of the crest types.

A probabilistic — and uncertainty analysis for the failure modes of a hydraulic structure is presented in this paper. First, a general approach for such kind of analysis is presented, followed by a case study. The study deals with the Ziaran diversion dam in Iran. Data has been collected during previous studies of this dam. In particular one failure mechanism is investigated in this paper in detail: overtopping by superelevation of the bend flume in the Ziaran Dam. This study focuses on the downstream water surface elevation during the flow considering the flume's actual discharge and roughness. Superelevation in the Ziaran Flume has led to severe erosion of the bank and to undermining of the structure. Therefore, this study aims to cast lights on the cause of overtopping by superelevation. By means of direct observation on the flume's hydraulic performance, during full discharge, and from generalization of the field data, a more reliable prediction method of the magnitude of superelevation has become possible. The probabilistic analysis will show to have several advantages in comparison with deterministic analysis methods.

The United States Department of Agricultural (USDA) Natural Resources Conservation Service (NRCS) has financially and technically assisted with the construction of nearly 11,000 small watershed dams in the U.S. By 2017, half of these structures will reach the end of their planned service life due to age, and others will need rehabilitation prematurely due to hazard classification changes as a result of urbanization and alterations in land use and topography. In many cases, spillways have inadequate spillway capacities. Approximately 10% of the 11,000 NRCS assisted structures are expected to have roller compacted concrete (RCC) stepped spillways to increase the spillway capacity of the existing structure. Typical RCC stepped spillways for NRCS applications will be constructed on existing embankments where the downstream embankment face slope ranges from 2(H):1(V) to 4(H):1(V). Literature in this realm of stepped spillways is very limited. A specific study utilizing a two-dimensional, 1:8 scale physical model was conducted to evaluate the design flow in a 4(H):1(V) stepped spillway chute and the effects air entrainment has on the design of the spillway training walls and stilling basin dimensions. Water surface and bed profiles were collected during testing. Observations show that the air entrainment inception point for relatively short spillway chute drops up to 12 m (40 ft) is expected near the bottom of the spillway chute for prototype flows higher than 7.0 m²/s (75 cfs/ft). For these flows, air entrainment is not expected to influence the design of the training walls significantly especially under high tailwater conditions. Spillway drops from 9.1 m to 12.2 m (30 to 40 ft) were tested with both stilling basin and riprap dimensions evaluated for dissipating the remaining flow energy. For the 9.1 m (30 ft) spillway drop, the stilling basin required to dissipate the remaining energy was approximately 36% longer than the stilling basin required for the 12.2 m (40 ft) spillway drop. Additionally, the end sill for the energy dissipating stilling basin for the 9.1 m (30 ft) spillway drop was 2 times the height required for the 12.2 m (40 ft) spillway drop. Yet, the hydraulic performance of the stilling basin for the 9.1 m (30 ft) spillway drop was undesirable, so the spillway was further tested with a drop height of 9.8 m (32 ft). This paper is intended to increase the knowledge and understanding of stepped spillways applied to relatively flat-sloped dam embankments and dimensioning of the energy dissipating stilling basin and associated riprap in the downstream channel.

Rapid advances in state-of-the-art computational fluid dynamics (CFD) analyses are being made in simulating multi-phase flow fields, particularly where fluid-structural member interactions, air-water interfaces (free surfaces), and bubbly mixtures are involved. Coupled equations link the Navier-Stokes equations of fluid motion with structural deformation equations to simulate both fluid and structural response to either steady-state or transient boundary conditions. Consequently, defensible calculations that are based on the best formulas used in engineering practice can be utilized for comprehensive hydraulic structural design. Problems associated with frothy free surfaces and bubble formation can now benefit from CFD implementation of research results regarding two-phase, air-water flow. A case study which illustrates the benefits of CFD analyses to guide difficult hydraulic structure designs is presented. The case study consists of flow through fixed cone valves (sometimes called Howell-Bunger or ring jet valves) into a stilling basin. These turbulent discharge conditions cause undesirable spray. CFD analyses were used to evaluate performance improvement options and assist with the final design alternative.

Folsom Dam is on the American River about 20 miles northeast of Sacramento, California. The dam was designed and built by the Corps of Engineers (COE) and transferred to Reclamation for operation and maintenance in 1956. The dam is a concrete gravity structure 340 ft high and impounds a reservoir of a little more than one million acre-ft. The existing dam features two tiers of four outlets each, controlled by 5- by 9-ft slide gates having a discharge capacity of approximately 700,000cfs. Updated PMF calculations require a total flood discharge in excess of 1,000,000cfs. To safely pass the PMF, an auxiliary spillway is proposed and as a design tool to ensure safe and efficient operation of the structure, a physical model study was utilized. Physical modeling was performed on the upstream portion of the proposed auxiliary spillway near the left abutment of Folsom Dam. The auxiliary spillway control structure will contain six submerged tainter gates (also known as top-seal radial gates) that can discharge about 300,000 cfs at a maximum pool elevation of 481 ft. Ayres Associates and Utah State University, with guidance from the USACE have utilized a physical model of the auxiliary spillway and the approach channel in the reservoir as a design tool.