World Environmental and Water Resources Congress 2013: Showcasing the Future

Cincinnati has been the center of federal water research for nearly 100 years. The early stream survey work of the United States Public Health Service (PHS) identified the factors that affect a stream's health eventually leading to water quality standards. Investigations into wastewater treatment methods led to the development of enhanced sedimentation; sophisticated biological treatment; and ultimately advanced waste treatment (AWT) processes for greater removal of solids, BOD, nutrients, organics, and even molecules and ions. This research laid the foundation for the later regulation of industrial and municipal discharges. Very early in the century (1914) the PHS had sufficient information to introduce drinking water standards and the concept of maximum contaminant levels for contaminants. These were revised and expanded over the years, especially with introduction of the Safe Drinking Water Act of 1974 and its reauthorization in 1996. With research came improvements in filtration processes; disinfection processes; control of biofilms and corrosion in piping; and the need to remove turbidity, arsenic, and in some cases fluoride to very low levels.

Arthur Morgan was born in 1878, the son of a Minnesota surveyor who joined his father as a partner. At age 26 he wrote the Minnesota Water Control Code, adopted in 1905. He then gained national notoriety as the Supervising Drainage Engineer of the U.S. Department of Agriculture from 1907-10. In 1910 Morgan founded the Morgan Engineering Company in Memphis, strategically located halfway up the Mississippi River. The firm specialized in flood plain drainage and reclamation. In March 1913 record flooding along the Miami River devastated Dayton, Ohio, drowning more than 300 people. Dayton's citizens hired Morgan Engineering Co. to develop a plan of "fail-safe flood control." Morgan moved his firm to Dayton to carry out the work and thrust himself into the research, design, and construction of a resilient flood control system, involving the entire watershed of the Miami River, some 3,937 square miles. The Miami Conservancy District required legal pioneering to formulate the agency on a solid legal foundation that would withstand a flood of challenges from the affected communities. Morgan's experience with drainage legislation west of the Mississippi proved invaluable. Morgan decided to design for a flow 40 percent above that of 1913. He devised an innovative plan using normally dry flood control basins rather than storage reservoirs, to provide flood storage and meter the peak flows. Five "dry dams" would be the largest embankment dams in the country and were bereft of any moving parts, so that they would indeed be "fail-safe." Morgan presented his scheme to the public on October 3, 1916, and the project was constructed over the next six years, being essentially complete by the end of 1922. The Miami Conservancy District became a model for other urban centers across the United States, such as Los Angeles, San Diego, and Pueblo. The necessary legislation was so novel it faced 61 legal challenges—all the way to the Supreme Court.

Chicago is a city that grew and prospered because of the vision and pioneering effort of its local leaders who conceived, financed, and implemented the reversal of the flow in the Chicago River to preserve public health and protect its source water, Lake Michigan. After more than a century of service, the man-made canal system continues to provide economy and efficiency in water transportation, protect public health and welfare by efficient drainage of treated wastewater and urban storm water, offer an amenity for waterfront property, allow reuse of water for industrial cooling, and be an outlet for those seeking water recreation in an intense urban setting. The first project to build a canal to reverse the flow of the Chicago River has proven to be a monumental and lasting effort.

A 1982 audiotape interview of Gordon G. Robeck, Director of the EPA Drinking Water Research Division in Cincinnati, conducted by James M. Symons (with the EPA in 1982) provided much of the following historical information. The PHS Drinking Water Standards began with the 1893 Interstate Quarantine Act under Treasury because of inspection of immigrants for disease. The 1912 PHS law included funds for establishment of a field Ohio R. unit to determine how stream pollution by waterborne diseases (typhoid fever and cholera) was endangering drinking water supplies. The Field Investigation Station (FIS) was located in the former Kilgour Mansion and in a PHS Marine Hospital in Cincinnati, converted for water research. At the Field Investigation Station, Ohio River water was pumped to a pilot plant for studies on water treatment and on septic tanks. The 1913-1914 Drinking Water Standards for Interstate Carrier Water Supplies preceded the 1925 Streeter and Phelps equations for Ohio R. dissolved oxygen levels. Research started on the effectiveness of sand filtration and chlorination for the protection of public health. In 1953, when the Department of Health, Education, and Welfare (HEW) was created, the PHS was included. In 1954, the water laboratory in Cincinnati moved out to Columbia Parkway to the newly constructed Robert A. Taft Sanitary Engineering Center, consolidating PHS offices from seven locations. Engineering and treatment studies received funding from the Navy and Civil Defense to counteract the possible sabotage of drinking water with planned treatment. The Cincinnati water lab moved administratively through federal changes from 1965 to 1970. In 1965, the Federal Water Quality Administration was formed, and in 1966 the pollution control staff (both civil service and Corps) was transferred to the Department of Interior. Starting in 1967, the PHS began rebuilding drinking water research. EPA, created in 1970, took over environmental programs among various federal agencies. The Federal Water Pollution Control Act of 1972 (commonly called "The Clean Water Act") led to the EPA's National Pollutant Discharge Elimination System, which controls discharges and construction grants. Funding under the Safe Drinking Water Act of 1974 led to research that supported drinking water regulations. At EWRI 2013, the Cincinnati Field Investigation Station Centennial will be held (1913-2013).

Lyndon Johnson's attitude toward polluted water was that the United States has a "moral imperative" to clean and restore its rivers. The Johnson Administration created America's first national water quality standards in 1965; enforced them without having to go to court; sought and spent funds to help cities build sewers and wastewater treatment plants to prevent, remove, and treat pollution; and helped the states develop water planning and water quality management programs. His administration supported training of new water quality professionals and research on difficult water quality problems, such as combined storm-sanitary sewerage and nonpoint pollution sources. The national water quality program the Johnson Administration put in place has thrived over the past 50 years and has improved surface water quality. Although President Johnson's successors have modified his program they also have kept its key elements in place, such as the relationships among the federal agencies, states, and local governments.

The Goldfields Water Supply (GWS) in Western Australia was a large public works project of global significance when it was built between 1896 and 1903.2 The project was the brainchild of Charles Yelverton O'Connor, an Irish civil engineer who came to Western Australia after a long and successful public works career in New Zealand. His deputy was Thomas Hodgson, a hydraulics engineer from Melbourne, Victoria. Together they designed and constructed a water supply system that consisted of what was then the highest dam in the southern hemisphere, eight steam-driven pumping stations, and 565 km (350 mi) of 760 mm (30 inch) diameter steel pipe that was capable of delivering 25.5 Ml/day (5.6 Mgal/day) of fresh water from the coastal city of Perth to the burgeoning gold mining town of Kalgoorlie.

The Boston Water and Sewer Commission has developed a 4,000-node EPA SWMM computer model to assess sources, loads, and mitigation alternatives for 13 pollutants discharging from the city's drain systems to its receiving waters. The model is calibrated to baseflow and stormwater runoff observed throughout a five-month flow monitoring program, water quality data obtained at 20 sites over six rainstorms and six dry-weather sampling events during the flow monitoring program, and historic data. The model has been used to assess the potential of improved best management practices, green stormwater infrastructure implementation, and low-impact development practices for meeting TMDLs and water quality standards. The model simulates buildup and washoff across nine land uses and contributions from groundwater, illicit flow, and rainfall. It simulates pollutant conveyance through open and closed conduit systems, first-order decay of oxygen demand, bacteria die-off, bacteria sources in sediment bed load, and pollutant removal through natural and constructed detention-treatment systems. The model is uniquely complex in its combination of detailed hydraulic representation of a city's natural and constructed drainage systems with dynamic water quality process simulation.

As part of the development of radar-based design storms in the Phoenix, AZ, area used for water infrastructure design, an analysis of expected antecedent moisture conditions was needed to support hydrologic-hydraulic modeling. Several hundred precipitation gauges found in Phoenix from 1994 to 2012 were identified and evaluated to find the ideal antecedent precipitation for a design storm. When using a design storm of a given frequency for infrastructure planning, some assumptions must be made regarding the moisture conditions likely present at the beginning of the storm. If a relatively rare moisture condition is assumed, the combined probabilities (i.e., event probability and antecedent moisture probability) can be quite different than the intended design frequency. The task reported herein used antecedent precipitation in the Phoenix area as a surrogate for antecedent moisture conditions. The study evaluated the likelihood of antecedent precipitation affecting the design storm response and found that dry antecedent moisture conditions can safely be assumed and are recommended for a design storm.

In the last several years, computational fluid dynamics (CFD) has emerged as a tool to accurately predict the response of best management practices (BMPs) to highly unsteady rainfall runoff (stormwater), particulate matter (PM), and metal and nutrient loadings. Commensurately, such predictive capability for highly unsteady loadings can require much higher computational time than steady loadings. Therefore to reduce computational time for a given level of accuracy, this study tests a quasi-steady modeling approach to reproduce the unsteady load response of three stormwater BMPs. These units are a hydrodynamic separator (HS), a granular media-based volumetric clarifying filtration system (VCF), and a primary clarifier (PC). The quasi-steady steps were determined based on creating a frequency distribution of flow rates loading each BMP. The quasi-steady steps required to accurately represent the unsteady PM clarification were a function of influent unsteadiness and the mechanisms of each unit. Modeled PM clarification reproduced measured PM data from each physical model tested in situ with a relative percent difference (RPD) of less than 10%. Results indicate that with up to 15 quasi-steady steps the measured load-response data generated from unsteady rainfall-runoff events was reproduced for the VCF but generated deviation for the HS and PC. The quasi-steady method reduced computational time by an order of magnitude, several hours, compared with a fully unsteady method. Results suggest that additional quasi-steady steps are required to reduce deviation for the PC and HS.

This study presents the findings from research conducted at the University of New Hampshire Stormwater Center (UNHSC), which investigated porous pavements as a potential strategy for minimizing the use of deicing chemicals for winter maintenance. In cold regions, chloride is an integral component of winter maintenance and safe usage of transportation surfaces. Chloride-laden runoff from impervious surfaces threatens aquatic habitat, degrades drinking water supplies, and corrodes infrastructure. State and federal environmental agencies are beginning to regulate chloride usage through the implementation of Total Maximum Daily Loads (TMDLs). Parking surfaces in some watershed studies have been shown to be the single largest chloride source in stormwater runoff , in some instances contributing up to 50% of the total load. This study examined winter maintenance over two winters and 38 storms from 2006-2008. The study evaluated winter performance in response to deicing practices by measuring skid resistance, the degree of snow and ice cover, recoverable chloride mass, and effective salt loads. During and just after snow storms, analysis of snow-ice cover and pavement skid resistance demonstrated that 64% to 77% less salt was needed for the porous asphalt (PA) lot to maintain equivalent or better surface conditions as compared with a reference dense mix asphalt (DMA) lot. In between snow storms, the lack of standing water on porous asphalt greatly reduced the frequency and mass of salt applications needed to control black ice. Although the DMA lot received a typical salt application that was four times greater, the annual median snow and ice surface cover for the PA lot was not significantly different (p=0.749 @95% confidence), and the annual median weighted skid resistance for the PA lot was 12% greater (p=0.061 @95% confidence). A companion study on the hydrologic and water quality performance reported that freeze thaw was limited due to the well-drained nature designed into the system, and surface infiltration capacities remained in excess of 500 cm/hr (200 in./hr), despite the fact that the maximum frost penetration depth observed was nearly 71 cm (28 in.). Porous pavements present one viable potential strategy for chloride reduction.

Current processes for developing Depth Area Reduction Factors (DARF), design storms, and temporal rainfall distributions from approximately 20 agencies as well as procedures identified in U.S. National Oceanic and Atmospheric Administration (NOAA) rainfall atlases were reviewed and benchmarked for the Contra Costa County Flood Control and Water Conservation District (District) in Martinez, CA. Most of the agency procedures reviewed use some variation of the NOAA Atlas DARF curves. Modified NOAA Atlas 2 procedures often follow the longer DARF duration (e.g., 3-24 hr) storms of NOAA Atlas 2 but use NOAA processes to create new DARFs for short durations (e.g., 5 min to 1 hr). Two agencies, the City of Colorado Springs and the Metropolitan Sewer District of St. Louis, are utilizing the growing database of radar rainfall estimates to develop DARF curves using a storm-centered approach. Most counties evaluated in this study rely on a rational method approach for small drainage areas, which requires an estimate of rainfall intensity. Each county or agency has a unique method for obtaining the rainfall intensity, but the differences among them appear minor. Only three of the counties or agencies reviewed have design storm procedures with additional steps for adjusting point rainfall estimates beyond applying a DARF factor. Typically, one of three general approaches is used in determining the temporal distribution of a design storm. The first is called a nested or balanced storm pattern. The second approach is the use of synthetic curves such as SCS types I, IA, II, and III. The third approach is the use of local historical data to develop a temporal distribution.

Sanitary sewer normal flow is usually estimated using domestic average daily flows estimated from per capita consumption (McGhee 1991). This research work was conducted for the sanitary sewer system of the Town of Highland, Indiana. The sanitary and storm sewer systems were separated in 1980s. Sanitary sewer discharge from this town is delivered to a nearby town called Hammond, which operates the waste water treatment plant through two outlets. For this study 5th Street basin, which contributes 60% of the load, was considered. Normal loads are usually handled comfortably by this system. But during high rainfall events, the sanitary sewer flow to Hammond is regulated due to capacity constraints. The Town of Highland initiated a modeling process to plan and design suitable alternatives to avoid this issue. Using USEPA SWMM modeling software version 5, the Town of Highland sewer system was modeled in this study. Using Tiger Census data, the population statistics were extracted for the town. Using ARC GIS software, the land use and soil details were extracted and used in this modeling. The whole system was subdivided into 15 subwatersheds. At all 15 subwatershed outlets, flow meters were installed and observations were made by covering low and high flow events. Using EPA-recommended daily typical variations in daily usage (Das 2011), initial low flow calibration was performed. High flow calibration was conducted by fine-tuning the infiltration parameters.

Many urban watersheds suffer from degraded water quality caused by stormwater runoff from rooftops, parking lots, streets, and other impervious surfaces. Low Impact Development (LID) is a design approach that utilizes stormwater control measures (SCMs) to maintain and restore the natural hydrologic features of an urban watershed through infiltration, runoff treatment at the source, and minimization of impervious surfaces. Limited peer-reviewed literature is available on impacts of multiple LID SCMs at a catchment or watershed scale. A paired watershed study with calibration and treatment monitoring periods has been designed to evaluate the hydrologic and water quality impacts of residential street SCMs at a catchment scale in Wilmington, North Carolina. Calibration monitoring of the control (0.35 ha) and retrofit (0.53 ha) catchments was completed from May 2011 to October 2011 (nine water quality samples, 14 rainfall events). In February 2012 bioretention bumpouts, permeable pavement parking stalls, and a tree filter device were installed in the retrofit catchment. Treatment monitoring commenced in June 2012 and will continue through February 2013 (10 water quality samples, 15 rainfall events through November 2012). Water quality, peak discharge, and flow volume are being recorded at the catchment outlets (existing catch basins). Water quality samples will be analyzed for TSS, TKN, NH₄-N, NO_2-3-N, TP, Ortho-P, Cu, Pb, and Zn. Preliminary results indicate a 14% reduction in mean runoff volume. TSS, TN, and TP mass loads at the retrofit outlet decreased by 83%, 49%, and 63%, respectively, during treatment monitoring. Preliminary water quality and runoff volume results are promising, and results from this project will help refine street retrofit design standards to meet runoff volume reduction and water quality goals.

This paper will describe the process the Town of Norfolk, CT, utilized to address water quality impairments in the Blackberry River by the creation of a "stormwater park" in the town center. Norfolk is a small community in the northwest corner of Connecticut. Commercial development in the town center is located on the east and west side of what is known as the "city meadow." Historically, the city meadow was used for grazing of cattle in the early 1900s. At the current time, it has become a degraded wetland with the dominant species being phragmities. Stormwater from state and local roads is discharged into the meadow and was determined to be the primary source of the nutrient impairment in the Blackberry River. The Board of Selectman appointed a group of concerned citizens to a committee to investigate and develop a plan to address the stormwater issues in the city meadow. The committee first reached out to the Northwest Conservation District (NCD) to evaluate the extent and quality of the wetlands in the city meadow. The author along with a representative of the NCD suggested that the committee hold a Charette for members of the public to obtain ideas for the city meadow. In addition to addressing stormwater issues, the public expressed a lot of interest in creating a public focal point in the meadow that would encourage the public to passively use the meadow area. Based on the feedback from the Charette, the author developed a conceptual design plan to address the stormwater quality issues while also creating an area where the public could gather. The city meadow committee developed a report based upon this concept and obtained funding from the Selectman to design the project. Two local landscape architects volunteered their time to assist in the layout of the public access components of the plan. To address the nutrient and other pollutants in the stormwater, a treatment train approach was utilized in the design. A forebay, wet swales, stone swales, constructed wetland system, and deep water pond were incorporated in the city meadow. Stone swales were incorporated to create an open water feature where two small waterfalls will increase the oxygen levels in the water. Fully compliant handicap paths were incorporated to provide"connectiveness" between the two commercial areas in the town center. Native plants will be used for all of the stormwater systems and for restoring the natural wet meadow areas, which are currently covered with invasive species. Educational signage is proposed to increase public awareness of the impacts of stormwater and how the newly constructed treatment systems will improve the water quality by natural processes. One of the goals of this project is to demonstrate how stormwater treatment can be incorporated into a public setting and become a public and environmental enhancement. This paper will also discuss methods used to engage the public and build community support for the project.

Evapotranspiration (ET) generally receives little attention in urban stormwater modeling, which often assumes a constant ET at monthly or seasonal intervals for an entire city area. However, unlike natural environments uniformly covered by pervious areas that accumulate and store rainwater for ET and infiltration, using the constant ET value to estimate runoff for the much more heterogeneous urban surfaces with checkered impervious areas and vegetation covers may lead to inaccurate estimates of ET and thus inaccuracies in long-term runoff volume estimates. And as new stormwater management approaches implementing green infrastructure and urban planning philosophies promoting green spaces advance, the impact of vegetation and ET on urban hydrology is increasing. To investigate this uncertainty related to ET, we test how finer consideration of ET in terms of spatial and temporal variations influence urban runoff estimation both in amount and time. We hypothesize that diverse types of land use/cover areas generate different impacts on ET and then the stormwater runoff due to their difference in storage capacity and ET rates. To test the hypothesis, the case study selected is a drainage catchment in Murray, Utah, located in the center of the Salt Lake City metropolitan area. EPA SWMM is employed in this study to simulate the water budget and estimate the runoff. The Eddy Covariance, Hargreaves method, and Penman Monteith equation are adopted to estimate the ET for different vegetation species and applied to different subcatchments in the city. The ET estimation results are imported into the SWMM model and used to test the influence of spatial and temporal variation of ET on the city's runoff reduction.

The focus of this project is the assessment of the potential for adsorption to reduce the concentration of dissolved heavy metals in runoff. One difficulty in evaluating adsorption in multicomponent systems is to capture the impacts of background organic matter and other complexing ions on adsorption behavior. The composition of the organic matter in stormwater runoff can be significantly different from natural organic matter typically used to assess the impact of background organics on metal ion adsorption. A compromise between using natural and synthetic storm water in this evaluation was therefore made by recognizing the importance of capturing the organic matter from natural storm water, but adding the flexibility of using laboratory chemicals to provide the inorganic constituents. To alleviate concerns associated with storing large volumes and aging of organic solutions, 1,000 gallons of storm water were collected and then concentrated by a factor of 150 using reverse osmosis. It was then freeze dried. The freeze-dried organic matter was reconstituted as needed at concentrations that mimic the initial total organic concentration of the stormwater when it was collected. A series of column experiments were then run using iron oxide, manganese oxide, Portland cement concrete, and crab shell waste as sorbents. Factors that were evaluated included organic matter concentration, competition between metal ion species (copper and zinc), pH, and ionic strength. The results of the column experiments indicate that iron oxide provides substantially better removal of dissolved metals than manganese. Portland cement concrete and crab shell waste were both found to be effective at controlling pH, which is the largest factor in determining dissolved metal removals. These experiments indicate that use of iron oxide augmented with either concrete or crab shell is potentially a cost-effective way to remove dissolved metals in highway runoff.

A bioinfiltration stormwater control measure (SCM) on Villanova University's campus was constructed in 2001 as a parking lot median retrofit in a residential student area. This SCM effectively mitigates stormwater runoff, including nutrients, and the study described in this paper comprehensively examines nitrogen removal. Both surface and subsurface stormwater samples collected throughout the site during the past nine years have been tested for nutrients, and, in particular, nitrogen species, which is the focus of this study. This objective is achieved by analyzing water quantity and nitrogen data to determine the fate of nitrogen in the bioinfiltration system from both surface and subsurface viewpoints. Parameters of interest are total nitrogen, total kjeldahl nitrogen, nitrate-nitrite, and nitrate. Stormwater samples are analyzed from inflow to outflow on a concentration and mass basis. Discharge for the system occurs as infiltration into in situ soil; any overflow leaves as outflow from a converted storm drain. Additional samples in surrounding background lysimeters and wells were tested for nitrogen species to compare with bioinfiltration samples. Results from the research will provide further insight on long-term water quality performance for an aged bioinfiltration stormwater control measure.

As nonpoint source pollution, storm water runoff is one of the main contributors to stream impairment in the United States and is primarily treated using best management practices (BMPs). One of the problems with BMPs is that the properties including the optimal composition and physical characteristics of the media used in bioretention basins are not well evaluated. The objective of this research is to evaluate treatment performance and physical characteristics of different alternative low-cost and/or low-weight media to be used in bioretention basins. Specifically, the use of rubber chips is evaluated as a possible supplemental medium because of their light weight and availability. Four types of rubber chip mediated soil mixtures were tested. It was found that a 50/50 mixture of rubber chips and sand had the best treatment, but lacked the best physical qualities for plant growth and may require addition of compost.

Civil engineers provide services aimed at meeting society's primary infrastructure needs in a safe and cost-effective manner. In most cases, work in one discipline does not adversely affect the value or sustainability of the resources and services in other disciplines. However, in the field of stormwater management, a case can be made that the opposite is true. Conventional stormwater management is widely documented as a primary driver of stream channel instability, which, in turn, causes adverse impacts to adjacent infrastructure such as roads, bridges, and utility lines. The fact that design decisions in one field result in a shortened design life of public/private assets from other disciplines is by definition unsustainable. Moreover, what's bad for our nation's infrastructure is also detrimental to the quality and biotic integrity of our water resources. By compiling available cost data of infrastructure damages attributable to channel instability in a Northern Kentucky case study, this paper underscores the business case for a recalibration of stormwater management for stream channel stability and infrastructure sustainability.

Lake Tohopekaliga is a 22,000-acre lake located within Osceola County in Central Florida. Lake Tohopekaliga has a long history of management activities that have altered the lake's natural hydrology and water quality over time. The lake was placed on the State of Florida's List of Impaired Waters in November 2010 for nutrients. Osceola County and the City of Kissimmee initially disagreed with the assessment through their own independent analysis. As a result, because Lake Tohopekaliga is a macrophyte-dominated lake (i.e., Hydrilla), the State of Florida acknowledged the assessment and was willing to reconsider the listing based on a macrophyte impairment and not develop a Total Maximum Daily Load (TMDL) for the lake. As part of the agreement with the State, the City and the County would need to provide assurance that proactive nutrient reductions (source controls) are taking place within the watershed while the lake dynamics are better understood and appropriate water quality targets can be developed. This paper describes the proactive process local stakeholders elected to develop a Nutrient Reduction Plan to satisfy the State of Florida's request. This decision allows lake interests and managers to avoid a reactive regulatory process (i.e., a TMDL) and to work toward solving the question of how water quality fits into the overall management of this lake.

The U.S. Environmental Protection Agency (USEPA) published technical guidance to help federal agencies in implementing Section 438 of the Energy Independence and Security Act of 2007, which requires federal development or redevelopment projects to preserve or restore predevelopment hydrology of the site. The technical guidance recommends retaining stormwater runoff from rainfall events equal to or less than the 95th percentile rainfall event by using a variety of stormwater management practices often referred to as Green Infrastructure or Low Impact Development practices. The 95th storm rainfall depths for a few selected cities were reported in the technical guidance. In this paper, the 95th percentile daily rainfall depths were computed following the USEPA guidelines from weather stations at 206 U.S. cities. An isohyetal map for the contiguous U.S. and supporting table with rainfall depths from the 206 weather stations were generated for 95th, 90th, and 85th percentiles, because the 90th or 85th percentile rainfall depths are extensively used in many stormwater management manuals in the U.S. to determine water quality volume. When compared with NOAA's 1-year 24-hour rainfall depths derived from TP-40 rainfall frequency atlas, the 95th percentile rainfall depths were smaller, and a correlation was developed between these two rainfall depths.

The Louisville Metropolitan Sewer District (MSD) has entered into a Consent Decree Agreement with U.S. EPA to reduce the number and volume of combined sewer overflows (CSOs) from the existing combined sewer system (CSS). As an aspect of this agreement MSD is using green infrastructure (GI) stormwater controls to reduce CSOs. The initial phase of the project is implementing GI controls in a small urbanized neighborhood (28 acres) in Louisville, KY, in lieu of a planned concrete retention basin. In December 2011, two permeable interlocking concrete pavement (ICP) controls were constructed. To quantify surface infiltration and subsurface exfiltration performance each control was embedded with time domain reflectometers (TDRs), thermistors, and piezometers. To predict the hydrological performance of the GI controls, a spreadsheet model is developed by utilizing each control's drainage area, hydraulic conductivity values for surrounding soil layers, and dimensions of each GI control. The model calculates the inflow and outflow volumes and predicts the water level inside the control for each rain event. Hydrological performance is defined as a GI control's ability to capture the runoff volume (infiltration capacity) and then pass captured volume into the underlying soil layers (exfiltration performance). The model's predicted water levels are compared with the recorded water levels by the embedded pressure transducers. The developed model predicts the ideal performance of the GI control and compares it to recorded data. This assessment technique works to quantify the progression of clogging at the surface and within the infiltration gallery. This model provides a method for monitoring the hydraulic performance of the GI controls over time.

Road runoff treatment is a challenge due to lack of space in the right of way. Therefore, it is imperative to understand the quality of runoff from roadways so that efficient stormwater control measures (SCMs) may be designed. In terms of TSS control, the particle size distribution of sediment in the runoff controls the amount of sediment (based on Stokes' Law) that may be removed through settling in a typical SCM. For best treatment of TSS, the flow depth in vegetated SCMs during the design storm should be limited to the height of the vegetation. Typical roadside stormwater controls (vegetated filter strips and swales) could be designed for water quality by calculating a hydraulic retention time for a particular removal of sediment. To do so, an understanding of average particle size distributions (PSDs) was needed for roads across North Carolina (NC). A field-monitoring study was conducted during May-November 2012 to obtain PSDs from roads in the three ecoregions of NC: mountains, piedmont, and coastal plain. Two sites in the mountains, six in the piedmont, and four in the coastal plain were monitored for TSS concentrations and PSDs for a minimum of six storms apiece. Roadway types were distributed across Interstate highways (six sites), four lane divided highways (one site), four lane primary roads (three sites), and secondary roads (two sites) to determine the effects that annual average daily traffic have on runoff PSDs. At the Interstate highway sites, two monitoring locations had a permeable friction course (PFC) overlay and one site had a NovaChip overlay, which may modify the expected PSD from a highway. Because nutrients are a concern in NC, nutrient concentrations (TN and TP) were monitored at four sites both in the stormwater and sorbed to the sediment. This will allow for modelling of nutrient removal performance for typical roadway SCMs by estimation of TSS removal from Stokes' Law. Gross solids (trash, debris, and particles greater than 5 mm in diameter) are often overlooked in loading of nutrients to waterways. Automated stormwater samplers are not able to capture most gross solids, and total maximum daily loads (TMDLs) for these pollutants have been established for some watersheds. Monitoring for gross solids was undertaken at four sites: one in the mountains, two in the piedmont, and one in the coastal plain. Three sites were Interstate highways while one was a divided four lane highway. Dry mass of gross solids and nitrogen and phosphorus content were determined in the laboratory. It was determined that gross solids are a substantial portion of the nutrient load, and that they cannot be disregarded in stormwater sampling for nutrient load estimation.

This study is part of a research project called HIDROECO, a network focused on quantifying changes in the hydrological cycle due to anthropogenic activities in urban watersheds located in Brazil's southern, southeastern, and northeastern regions. One of the main challenges the planner faces is to anticipate and manage the impacts before they become reality. Within this context, it is crucial to conduct studies that afford forecasts, especially in watersheds undergoing urbanization, such as the Mineirinho brook watershed, located in São Carlos, Brazil. Thus, the objective of this study is to carry out quantitative and qualitative water analyses considering different land use scenarios and using geoprocessing and mathematical modeling tools. This study evidenced the need for monitoring and calibration of runoff and non-point source pollution models parameters, given that the runoff volume and pollutant loads generated depend on many variables, such as land use patterns, hydrological and topographic characteristics of the watershed, vegetation, season, street sweeping, and practices of urban space management.

The primary objective of Low Impact Development (LID) is to maintain pre-development hydrology. This has been achieved by matching the magnitude and duration of pre- and post-development hydrographs. Research on undeveloped watersheds show that stream storm hydrographs are composed of water from one of three pathways: 1) surface runoff, 2) shallow interflow, or 3) groundwater surge. Each of these pathways offers different treatment benefits and is thus essential for optimal nutrient reduction. Stormwater Control Measures (SCMs) providing opportunities for each of these pathways may be better able to mimic pre-development hydrology, particularly in terms of water quality. This research aims to partition the pre-development hydrograph and estimate pre-development water quality. Previous studies on forested watersheds are referenced to establish target hydrograph fractions. Ultimately, this research better defines the goal of pre-development hydrology, while suggesting SCM characteristics to provide opportunities to best mimic pre-development conditions.

The regional scale performance of domestic rain water harvesting tanks are analyzed in this paper. The analysis is based on the daily water balance simulation of the storage tank using the yield-after-spillage algorithm as tank release rule. Water balances are applied to a number of rainfall gauging stations in Sicily, the larger island in southern Italy. A dimensionless methodology that was recently developed by the authors is here applied to describe the effects of the intraannual character of the rainfall patterns in the harvesting systems. As result, easy-to-use regional regressive models to evaluate the water-saving performance and the discharged overflows from the tank are provided. The regional models showed good fits between model predictions and simulated values of both water savings and overflows from the tank.

In many green infrastructure systems and low impact development systems, mechanistic control has occasionally been investigated. Also only selected studies have modeled the performance of such systems under transient and unsteady conditions. Therefore in this study, the computational fluid dynamics (CFD) model was applied to simulate the performance of an existing green infrastructure system, a stormwater partial exfiltration system (PES), located on Interstate Highway 75 (I-75) in Cincinnati, Ohio. The system comprises a linear porous media reactor of oxide-coated granular substrate media (OCS) capped by an infiltrating surface of cementitious permeable pavement (CPP). Results indicate that the CFD model is a feasible and accurate tool to simulate the performance of PES in three circumstances: stochastic storm events (unsteady flow), different influent flow rates (steady flow), and long-term performance (on an annual basis). For unsteady flow simulation differences between modeled and measured effluent PSDs are not significant for the database of monitored events. For event simulations, removal efficiency of particulate matter (PM) is greater than 90% for the PES under any flow rate conditions. Considering annual infiltrated flows only, the PM removal efficiency of the PES is 97%. If annual infiltrated and bypass flows over the CPP (combined, the influent to the PES) are considered, the PM removal efficiency is 68% based on continuous simulation for a year of data.

The article presents a method to study the changes of urban catchment runoff behavior from green roof implementation. The proposed method takes into account the thresholds in green roof response and abrupt changes in areal characteristics, which allows the method to correctly scale various types of green roofs, and ultimately other BMPs, for a range of storm characteristics and BMP implementation. We used the Illinois Urban Hydrologic model (IUHM) as a base model for urban sewer systems, with the incorporation of a green roof model that was developed to simulate the major processes affecting the hydrologic response of green roofs. The modified IUHM model, herein named Combined IUHM-Green Roof Model (CIGM) was used to test green roof impact on hydrologic response at a catchment scale. Results indicate that the implementation of green roofs has a distinct effect on decreasing the volume and peak of urban storm water runoff and postponing the time to peak runoff. The volume and peak discharge reduction depends on the temporal distribution of rainfall and the volume of rainfall and green roof coverage.

Computational fluid dynamics (CFD) is an emerging tool to predict the coupled hydrodynamics and particulate matter (PM) fate in unit operations (UOs) subject to rainfall-runoff events. Most studies examine unit operations on an event basis. This study also includes event-based analysis extended to time-domain continuous simulation using the Stormwater Management Model (SWMM) to evaluate unit operation performance on a long-term basis with and without maintenance. A validated computational fluid dynamics model simulated particulate matter fate in a rectangular clarifier (RC) and a screened hydrodynamic separator (SHS) for a representative year of runoff in a North Florida source area. The clarifier and SHS are fundamentally different unit operations with differing behavior, applications, and functionality. The objective of the study is to illustrate the modeling of these two unique, but common units. The large footprint clarifier with volumetric capacity is a primary treatment unit operation while the SHS is a pretreatment gross solids trap without storage. Results indicate that the SHS is prone to washout without frequent maintenance. While neglecting particulate matter washout from the SHS overestimates SHS annual performance, this was not the case for the clarifier. For unit operations, computational fluid dynamics and time-domain continuous simulation models are tools to estimate fate of particulate matter and nutrients on an annual basis. Examined on an annual basis the mean cost (USD) to recover 1.0 lb (0.45 kg) of particulate matter (PM) (irrespective of particle size because the SHS is a gross solids trap) is $4 (SHS), $10 (clarifier), and for comparison, $15 (radial cartridge filter) without pre- or primary treatment required (and associated costs) by such filters. This compares with street sweeping at $0.10 to recover 1.0 lb of PM.

Many challenges are associated with choosing the most effective stormwater management device or treatment train for contaminant removal at a particular site, including determining the appropriate treatment technology and sizing the device. Current guidance documents provide estimated percent removals for a select group of pollutants (usually nutrients and total suspended solids [TSS]) and a set of design criteria, usually based on the size of either the drainage area or the impervious area. The objective of this study is to determine the design criteria that will improve the prediction of removal performance and develop a more effective way to design appropriate treatment technologies to eliminate the problematic contaminants in runoff water at a specific site. This project, in its earliest stages, has focused initially on determining whether relationships exist between inflow and outflow concentrations for three devices: bioretention basins, infiltration trenches, and retention ponds.

This paper presents an economic feasibility analysis of a new site-level stormwater reuse system for commercial sites in Canada. The new reuse system utilizes captured stormwater from an on-site stormwater management (SWM) pond and temporarily detains the treated water in an underground storage facility for reuse. The reclaimed water is distributed for nonpotable end uses such as toilet flushing and irrigation in commercial buildings on site. Research has indicated that the reuse system can achieve a potable water replacement between 63% and 99% for single-commercial developments across Canada. Results from the hydrologic analysis were used to evaluate capital and operating costs and expected water savings for a novel large-scale stormwater reuse system. Preliminary results indicate favorable pay-back periods for implementation in municipalities across Canada.

The purpose of this paper is to evaluate the hydrologic performance of a novel stormwater reuse system for implementation in commercial developments in Canada. The performance of the new reuse system was tested on single-commercial sites located in the six Canadian cities of Vancouver, Edmonton, Saskatoon, Regina, Toronto, and Quebec. Historical rainfall data and SWMM 5.0 were used to perform continuous simulations and evaluate the potential of the reuse system to replace potable water for toilet flushing and garden irrigation. The results indicate that potable water can be replaced with reclaimed stormwater for nonpotable end uses (toilet/urinal flushing and irrigation) at a rate between 63% and 99% for single-commercial developments across Canada.

Biofilter, bioretention, and raingardens all rely on biomedia to remove solids, nutrients, and metals and to support viable plant growth. In response to the growing interest in low impact development (LID), many studies of biomedia have focused on pollutant removal performance. However, some fundamental questions central to the biomedia longevity and maintenance requirements remain unclear, which often impedes a sound comparison of different practices and sometimes leads to improper biofilter design and deployment. Once biomedia is clogged, incoming stormwater runoff is either bypassed or ponded without treatment and no water quality improvement is attained. Therefore it is critical to study the biofilter service time and the needed maintenance scheme in addition to the performance. To this end, this paper investigated UrbanGreen (UG) biomedia loading and longevity with natural stormwater solids (less than 500 μm) instead of silica material. A series of iterative loading tests with natural stormwater solids were carried out to clog select biomedia. To evaluate the restorability of biomedia infiltration capacities, each test was followed by surficial biomedia replacement to mimic standard maintenance practices. The average natural stormwater sediments concentration was controlled at an approximate level of 200 mg/L. The biomedia depth was 24 in. and constant infiltration rate of 100 in./hr was maintained throughout the testing. The experiment was completed after 12 cycles. The average surface loading rate for each cycle is 2.3 lb/ft^2 with standard deviation of 0.49 lb/ft^2. The cumulative loading capacities warrant UG biomedia a minimum service life of 5-10 years depending on the specific site loading conditions and biofilter sizing. The results provide valuable information that can be used to predict maintenance intervals and service life of biomedia treatment systems.

Little information is available on stormwater runoff loadings from urbanized coastal watersheds in the northern Gulf of Mexico. Stormwater discharges from pristine or least (Heron), moderately (Cumbest), and heavily (Chico) urbanized watersheds in Mississippi, were monitored from June 2010 to July 2011 to quantify loadings of nutrients and sediments. There was zero and one discharging pipe available for effective sampling in the Heron and Cumbest watersheds, respectively. The Chico watershed had 83 discharging pipes and was divided into five sections for sampling based on pipe location, size, and accessibility. Annual loads (kg·ha-1·yr-1) of total suspended solids (Chico large = 322.71, medium = 137.72, and small = 1.38; Cumbest = 0.04 x 10-1) were extremely high from both large and medium pipes at the heavily urbanized watershed. Nutrient loads followed the similar trend (e.g., NO3- loading large = 16.04, medium = 4.31, small = 0.05, Cumbest = 0.02 x 10-2). Results of this study suggest that watershed urbanization increased solid and nutrient loads to adjacent surface waters. These results may be helpful for TMDLs development for urbanized coastal watersheds.

The Raritan River has a history of overflowing its banks and causing substantial damage to nearby townships and boroughs. In this study, a hydrological model was developed for the Raritan Basin. The calibrated model was subsequently used to compute the reduction in stream flow as a result of implementing sufficient green infrastructure to reduce runoff depth by one inch throughout a chosen watershed management area. To simulate the runoff reduction, the curve number corresponding to the reduced runoff was back calculated. Changing the curve number also changes the lag time and initial abstraction so these values were adjusted accordingly. In terms of discharge, the peak flow would pass from approximately 30,000 cfs to just under 20,000 cfs. The reduction in the stream was then translated to the reduction in the stream water level using the established rating curve. The types of green infrastructure that can be used to reduce one inch of runoff were also assessed, and their costs were estimated as well.

Over the past 10 years green roof has been considered an effective stormwater management tool to mitigate storm runoff in urban environment. However, the hydrologic and hydraulic processes of the green roof have not been adequately modeled. Existing approaches range from relatively simplistic infiltration models to more complex subsurface and groundwater flow models. None of these models consider the preferential or nonequilibrium flow in the layers of green roof. In this paper we present a green roof model developed based on preferential flow that accounts for the water movement between the matrix and fractures in the growth medium. The model is calibrated and validated using three years of monitoring data from multiple roofs in Seattle, Washington. The simulation results of the peak flow and total volume matched well with the observations.

A controlled water release experiment that took place on the pervious concrete parking lot area in Randolph, Vermont, gave rise to a very interesting and unique data set. The counterintuitive groundwater level response that was observed in the wells located on the pervious concrete area was stronger in close proximity to the water release source. Comparison to groundwater level data observed in the same locations during the time that hurricane Irene reached Vermont shows that the counterintuitive response was unique to the water release event. The strange phenomenon is believed to be the result of the sudden load application caused by the release of water on the soil located below the pervious concrete area leading to deformation of the aquifer and consequently a local change in porosity. The porosity change, which, according to the literature, can be linked to a change in void ratio and finally permeability, would then alter the vertical flow gradient through a release of the very high near-surface pore pressure that could potentially lead to a significant drop in groundwater levels.

Benthic macroinvertebrates, which are sensitive to water pollution, are important indicators in determining health status of stream ecosystems. Wu Gou Shui is located in an area with upwelling water and suitable for studying the relationship between hyporheic zone and stream environmental condition, such as physical, chemical, and biological variables. This research was conducted during the March to May 2012 period at Wu Gou Shui Area, Pingtung County, Taiwan. Benthic macroinvertebrates were collected with kick sampling and Surber sampler methods. Chemical (dissolved oxygen [DO], pH, electric conductivity, turbidity, and chlorophyll a) and physical (flow velocity, water depth, and gravel composition) environmental conditions were also measured to compare with the macroinvertebrate data. Upwelling and downwelling hyporheic waters were determined by using a minipiezometer along Wu Gou Shui and later analyzed for their relationships to environmental variables. The results show that abundance of benthic macroinvertebrates was positively correlated with flow velocity and negatively correlated with water depth. Number of taxa was positively correlated with flow velocity. Abundance of mayflies was negatively correlated with water depth. The vertical hydraulic gradient (VHG) was negatively correlated with water depth and electric conductivity but positively correlated with DO.

The City of Enid collects most of its water for public distribution from groundwater. This groundwater is supplied from five wellfields covering the Enid Terrace Aquifer, the Drummond Confined Aquifer, and the Central Oklahoma Aquifer. The five wellfields include Enid Wellfield, Drummond Wellfield, Cleo Springs Wellfield, Ringwood Wellfield, and Ames Wellfield. This research explores nitrate distribution in the aquifer by analyzing breakthrough curves for the wells and estimating nitrate plumes for the wellfields. The Environmental Protection Agency requires that all public water have a nitrate concentration of less than 10 mg/L as this level causes Blue Baby Syndrome in infants. Information for this study was provided in the form of sampling data compiled by the City of Enid. This raw data was then analyzed and distilled to determine nitrate existence and extent using Environmental Protection Agency standards. This paper presents a methodology to delineate the high nitrate plumes in five wellfields.

Groundwater has been an important source for agriculture irrigation in the High Plains Aquifer Region and caused decreasing stream flow since the 1950s. Irrigation return flow complicates the stream depletion problem, as it partially offsets the flow decrease caused by groundwater pumping. The stream flow recorded at stream gauges is a composite consequence from the dynamic interactions between surface water (SW) and groundwater (GW) systems, which have been aggravated by human activities. This study examines the complexity through a modified version of Soil and Water Assessment Tool (SWAT). An aquifer storage component is modified to the original SWAT, which allows the model to simulate the complicating effects of groundwater pumping and irrigation return flow on natural stream flow. The model is applied to the Frenchman Creek Basin, Nebraska. Results show that intensive pumping reverses the natural seasonal groundwater recharge pattern, from "summer recharge and winter discharge" under natural conditions to "summer discharge and winter recharge" under the human interferences. The irrigation-induced flow becomes a considerable portion of stream flow during the crop-growing season, implying that fluvial ecosystems may rely on return flows and be affected by irrigation practices. Conjunctive surface and ground water management has the potential to balance irrigation requirement and environmental flow conservation.

In regions of the world where growing population and changing climates are threatening water supplies, accurate modeling of potential human impacts on water resources is becoming more important. Stream depletion, the reduction of surface water flow due to the extraction of groundwater from a hydraulically connected aquifer, is a direct way that development can alter water availability. Thus, the accurate modeling of stream depletion is an important step in siting new groundwater wells. Proper estimation of stream depletion requires appropriate parameterization of aquifer and streambed hydraulic properties. Although many studies have conducted numerical investigations to determine stream depletion at specific sites, they typically do not use measured streambed hydraulic conductivity (K3), but rather assume a representative value. These assumptions are inaccurate for natural systems because Kr varies spatially along the stream channel. In this work, we investigate how stream depletion is affected by spatially-variable conductance, given by C = wKr/br, where C is conductance, w is the width of the stream, Kr is the streambed hydraulic conductivity, and br is the thickness of the streambed. The conductance of the model stream channel is varied along the flow axis with regions of relatively high conductance along the straight sections and regions of relatively low conductance along the bent sections. This was done to better represent the conductance patterns in a natural system. It was found that altering the value of conductance along the stream channel can affect stream depletion estimations to a significant degree. For example, if attempting to determine the optimal placement of a pumping well in an aquifer to minimize its effect on the stream, modeling stream depletion with conductance values that vary along the stream channel will alter favorable well locations. The numerical simulations show that in situations such as the one described, accounting for the natural variations of conductance will be necessary to develop an accurate model of a stream-aquifer system.

Remediation of contaminated aquifers is necessary to protect fresh water resources. Because sorbing contaminants remain attached to the soil matrix, they are difficult to remove by pump-and-treat remediation; thus, sorbing contaminants lead to long-term degradation of aquifer water quality and in situ remediation techniques are preferred for the remediation of sorbing groundwater contaminants. In this work, we investigate the use of engineered injection and extraction as a method of enhancing in situ remediation of sorbing groundwater contaminants. With engineered injection and extraction, a treatment solution that reacts with the contaminant is injected into the contaminated aquifer, and a series of injections and extractions of clean water are performed in nearby wells to promote the spreading of the treatment solution throughout the contaminated aquifer. Using numerical simulations, we investigate the appropriate injection and extraction sequences for a range of sorption parameters and reaction kinetics. We show that engineered injection and extraction lead to an increase in the amount of reaction that occurs between the treatment solution and the groundwater contaminant and therefore enhance in situ remediation.

In this paper, MODFLOW was used to investigate the long-term injection and recovery of freshwater in the brackish aquifer of Wadi Ham, United Arab Emirates. The simulations were conducted for six successive cycles of injection and recovery with constant recharge and recovery rates and also constant durations. The simulations were also performed for various rates of injection and recovery and the recovery efficiency of the system was evaluated. The recovery efficiency varied between 32% and 88% and increased significantly during the first three cycles and then slightly in the following runs. The effect of the injection and recovery rates and the duration of the recharge were also investigated.

Groundwater is an important source of water for the agricultural, domestic, and industrial sectors. For proper planning and management of groundwater development in a judicious and socioeconomically equitable manner, quantification of groundwater resources is one of the most important prerequisites. In the present study Visual MODFLOW has been applied to get a better understanding of the groundwater flow system of Banas River basin in Rajasthan state in India. The model attributes like recharge rate, water level in observation wells, extraction values, river stage and flow rates, hydraulic conductivity, and ground surface elevations were available. In the upper (hilly) reaches basin boundaries have assumed no flow boundaries. The grid cell size of 500 m by 500 m was been used in the model. The model output (after validation and calibration) in terms of head, drawdown, flow direction, etc., has resulted in insight into groundwater scenarios in the study area that may be useful for judicious and planned exploitation of the groundwater resources and also for the evaluation of climate change impacts.

This paper investigates the hydrodynamics in a tidally influenced sandy beach polluted by the Deepwater Horizon (DWH) oil spill. The oil was brought to the beach during a storm, and subsequent wave activity buried it under about 0.15 m of clean sand. We obtained field measurements of water table, pore water salinity, and soil moisture at a transect, and we used the two-dimensional finite element model MARUN (Boufadel et al. 1999) to simulate water flow below and above the transient water table while taking into account the effect of salt concentration on water density. The model was calibrated by fitting to the observed data and numerical simulations demonstrated the following: As the water was approximately one meter below ground surface, the physical washout of the buried oil by groundwater flow seems impossible. High salinity was observed in both landward well (~25 g/l) and seaward well (~39 g/l). This was probably because the beach is bounded on the landward side by Pensacola Bay, which has a salinity comparable to that of the Gulf of Mexico. The soil moisture in the oil-contaminated layer of the beach was around 20%~30%, indicating the oiled sediment was unsaturated. This range appears to be sufficient for the biodegradation of oil based on the literature.

Surface microtopography affects infiltration and soil-water flow (both magnitude and direction). The objective of this study is to evaluate the final distribution of wetting front under the influence of surface microtopography. Laboratory-scale infiltration and unsaturated flow experiments were conducted for various microtopographic surfaces and boundary conditions. In addition, two- and three-dimensional numerical modeling was conducted using the HYDRUS software. The simulated wetting front distributions were compared. The results from this combined experimental and modeling study indicated that surface microtopography had strong influences on soil water movement. A uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing to reach the uniform flat wetting front varied, depending on surface microtopography, soil hydraulic properties, and boundary conditions.

Hydrogeological parameters of leaky aquifers are very important in site characterization, so these parameters are necessary information for quantitative and qualitative groundwater studies. In this paper, different methods were used to evaluate and predict the effective factors of leaky aquifer including the storage and transmissivity coefficients and hydraulic conductivity for four aquifer types classified as A, B, C and D. Pumping test was considered to calculate the storage and transmissivity coefficients experimentally and numerically. Also, Constant Head test, Single Well test, Double Well test, and Hazen formula were considered to obtain the hydraulic conductivity. Furthermore, several feed-forward two-layer artificial neural networks were trained to predict the storage coefficient, transmissivity, and hydraulic conductivity using these tests, models, or formulas. Finally, the sensitivity analysis of all these hydrogeological parameters against the change of each parameter such as discharge and the size of the gravel of the soil was done. Results indicated the behavior of the hydrogeological parameters against each parameter.

Although in situ treatment methods exist for groundwater contamination remediation, it is often difficult to increase the efficiency of the reactions under time constraints. During in situ remediation, a treatment solution is injected into the contaminated region of the aquifer to react with and degrade the groundwater contaminant. Ideally, the treatment solution should be spread throughout the contaminated region to increase its contact with the contaminant, leading to more opportunities for degradation reactions. Engineered injection and extraction (EIE) is a promising technique for generating spreading, in which transient flow fields are induced using a sequence of injections and extractions of clean water at wells surrounding the contaminant plumes. While simulations of in situ remediation using a single unique sequence of EIE have shown that spreading due to EIE can enhance reaction, a new approach is needed to design high-quality EIE designs that consider multiple engineering performance objectives. This study uses a multiobjective evolutionary algorithm (MOEA) to determine a set of EIE designs that balance multiple objectives, such as maximizing the amount of reaction while minimizing the amounts of required treatment solution and extracted groundwater contaminant. Such tradeoff surfaces allow stakeholders to determine how EIE designs perform under various degrees of aquifer heterogeneity, types of contaminant (aqueous or sorbed), number of wells, and location of wells.

This paper presents a hydrodynamic and water quality modeling system for Fuzhou Section of the Minjiang River. Historical water quality monitoring and pollution surveys show that lots of water pollution sources were located close to the protection zone of drinking water sources of Fuzhou City. To obtain quantitative knowledge about the water environment in Fuzhou section of the Minjiang River and protect the drinking water source, an integrated modeling system was developed based on environmental fluid dynamics code (EFDC) and water quality analysis simulation program (WASP) modeling framework. The EFDC was used to simulate hydrodynamic in the river, and the resulting flow information was incorporated into the WASP to simulate the balance of dissolved oxygen. Using data in different hydrological conditions, model calibration and model validation were conducted in this paper. Three scenarios of water environmental management were designed in this paper. Scenario analyses were conducted using the developed model system to evaluate the water quality variations influenced by pollution sources. The results indicate that the tide downstream has a distinct influence on the hydrodynamics, there is a weak diffusion condition during the process of pollutants on migration in the tidal reach, and the model will provide an effective tool to ensure drinking water security.

This study proposes a convenient definition of the Forchheimer number for multiphase to derive a generalized Darcy-Forchheimer model. Based on this, a numerical tool using control volume finite difference method has been developed to simulate two-phase inertial immiscible and incompressible flow in nondeformable homogeneous porous media. The numerical tool has been validated by comparing the results to those obtained using a semi-analytical solution to the Buckley-Leverett problem with inertial effects and showing good agreement with the analytical solution. This study also proposes a new method to determine the critical Forchheimer number for the transition between Darcy flow and Forchheimer flow for both single phase and multiple phases and obtains the critical values for both water and CO2 by using the new method and experimental data in the literature. These critical Forchheimer numbers are then incorporated into the multiphase model. A comparison between the classical Darcy flow model and the Darcy-Forchheimer flow is conducted to reveal the importance of non-Darcy effect for high velocity case. This study provides a useful tool for future analysis and comprehension of multiphase Darcy-Forchheimer flow.

We address the performance of an aquifer system where water is extracted at a given baseline pumping rate under the following conditions: 1) catastrophic events such as saltwater intrusion or pollution can interrupt water extraction, 2) recharge is a stochastic process, and 3) the possibility of management to reduce the pumping rate if necessary is limited. We argue that the mathematical framework of stochastic viability theory is relevant for addressing this problem and for complementing the usual performance indicators of reliability, resiliency, and vulnerability (R-R-V), which alone are not adapted to describe situations where the baseline pumping rate cannot be restored. Indeed, viability theory allows for the derivation of the stochastic viability kernel, defined as the set of all the values of the aquifer storage for which the baseline pumping rate can be applied while ensuring continued water extraction with a high probability in a large time horizon. For lower values of aquifer storage, pumping has to be reduced to avoid adverse events, so that the baseline pumping rate cannot be met. Viability theory allows for finding the management actions that minimize the risk of event occurrence. For a given baseline pumping rate and for given limits to management, one can then derive R-R-V indicators to describe the performance of the system. This viability framework provides insights into the connection between the choice of higher baseline extraction rates and a lower system performance. Besides, the values of these indicators increase when management can reduce pumping rates more quickly, thus showing the importance of empowering management instances, both to avoid catastrophes and to have an effective extraction policy. The applicability of the framework to conditions of extreme droughts is also discussed.

More than 20 years after 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, the oil still persists on some of the previously polluted beaches. As part of the investigation for the persistence of oil, we conducted a field study for water flow and solute transport along a clean transect of a tidal beach in Smith Island, Prince William Sound (PWS), Alaska that was heavily polluted by the spill. Field measurements of water table and pore water salinity were obtained, and the results were modeled numerically by the model MARUN (MARUN is a finite element model capable of simulating water flow and solute transport in variably saturated media while taking into account the effect of salt concentration on water density and viscosity). A random-walk particle tracking code was also used to investigate the flow path in the sediment. The simulations reproduced the observed water table and salinity accurately. The results suggested that the beach has two layers of very different hydraulic properties: A high permeability upper layer underlain by a low permeability layer. Particle tracking results indicated that the average pore water velocity in the upper layer and lower layer was 8 m/hour and 5.7×10-3 m/hour, respectively. We believe that due to the high freshwater recharge into this beach, the water table always remained above the interface of the two layers. Therefore, oil could not penetrate into the lower layer and persist there for a long period of time.

Solute exchange between overlying water and the sediment bed of a stream have important effects on the chemical mass balance and biological activities in both the water column and the sediment. Previous studies did not consider the coupled and cumulative contributions of turbulence in the overlying water, water surface waves, and underflow to the solute transport in the Interfacial Exchange Zone (IEZ), although these processes have been studied individually. To investigate the interaction, eight carefully designed experiments of solute exchange in the pore system of a stream gravel bed were conducted. The data analysis showed that the turbulent flow over the bed, the underflow, and the wave-induced advection enhanced the solute exchange and penetration of a conservative solute into a stream gravel bed. The maximum penetration depth under the turbulent current was 15 cm in 3000s; however, the penetration depth reached 20 cm in less than 1000s when surface waves were present. A coupled hydrodynamic and solute transport model was developed to estimate vertical dispersion coefficients for solutes in a porous and permeable streambed. The enhanced dispersion coefficient that combines all three processes is a function of the near-bed coherent motion due to the turbulent current, relative dispersivity (longitudinal dispersivity/wave length), wave steepness, sediment hydraulic conductivity, and sediment porosity, and decreases exponentially with depth; however, the turbulence-enhanced dispersion without the wave effects is smaller and diminishes faster with depth compared with the wave-enhanced dispersion.

Minnehaha Creek is among the most valued natural resources in the Minneapolis, MN metro area. However, frequent drought periods—which have left the creek dry in nine of the last 13 years—impair both the ecological and cultural value of the creek. Rapid rises and falls in streamflow due to stormwater runoff contribute further to flow-related impairments in Minnehaha Creek. We hypothesize that flow in the creek during low-flow periods could be augmented through strategic infiltration and storage of stormwater runoff in the shallow aquifer feeding the creek. Existing hydrogeologic data suggest sustained base flow in Minnehaha Creek is limited due to rapid vertical transmission of recharged groundwater to underlying bedrock aquifers, the vertical travel time of which is on the order of 0.5 years. A streamflow-based systems model applied to infer physical characteristics of the shallow aquifer system indicated that the area of the contributing aquifer system is less than 1% of the creek's watershed area. O-18 and dueterium isotope signatures likewise indicate limited groundwater inputs to the stream system. However, site-level field measurements of groundwater-surface water interactions—including thermal mapping, streambed seepage rate measurements, and monitoring of piezometric heads throughout the creek's riparian area—indicate there may be opportunities to augment base flow if infiltration occurs in select regions. The understanding of surface-groundwater exchanges in Minnehaha Creek gained through field measurements will be used to inform stormwater management efforts as to opportunities to capture stormwater for augmentation of base flow.

Shahrekord aquifer is located in Chahrmah-Va-Bakhtiyari province, Iran, and is a source for drinking water. The main objectives of this study were 1) to examine the seasonal fluctuations of nitrate and phosphate concentrations and patterns in the aquifer and 2) to evaluate the effect of sampling time of nitrate and phosphate on the accuracy of the prediction DRASTIC and SINTACS models. Almost 100 agricultural wells were sampled four times in 2010 and 2011, and nitrate and phosphate concentrations were measured in the samples. Geostatistical methods were used for mapping of nitrate and phosphate concentrations within the aquifer. The results show that the aquifer nitrate concentration varied between nil to 55mg/L and that of phosphate concentration between 0.07 to 0.15 mg/L. Mean concentrations of nitrate and phosphate during three seasons (spring, summer, and fall) significantly changed. In the fall, almost two-thirds of the aquifer (especially in northern parts) had a lower nitrate concentration (between 0 to 20 mg/L). However, the southern part of the aquifer is relatively polluted, and nitrate concentrations exceed the Iran water quality standard limit (45 mg/L). Groundwater vulnerability maps show areas with the relative potential for contamination. Comparison of nitrate or phosphate concentrations with an aquifer vulnerability map during spring, summer, and fall showed that the results of DRASTIC and SINTACS models can be somewhat sampling time dependent for both constituents (nitrate or phosphate). There is a significant difference between the correlation of nitrate or phosphate with SINTACS or DRASTIC maps with sampling time during the year. The largest correlation was seen in the spring and the lowest correlation occurred at the end of summer. Thus, to verify DRASTIC and SINTACS models, the sampling time of pollutant must be considered. Concentration of both nitrate and phosphate increased, i.e., nitrate concentration from 18 to 27 mg /L, and phosphate concentration from 0.05 to 0.15 mg/L during the period 2006 to 2011. Comparison of maps shows that the contamination of both nitrate and phosphate has increased in the area, during the years 2006 to 2011. During this period, the zone of low contamination has shrunk and the zone of high contamination has expanded.

This paper describes a comprehensive set of computational models developed for different phases of emergency management of drinking water distribution system contamination events. These phases include contamination risk assessment, emergency preparedness, and emergency response. Emphasis will be placed on interconnections among management phases to prepare an integrated emergency management system. Risk assessment identifies the most critical contamination events. Emergency preparedness is performed to identify a set of representative scenarios. Optimal emergency response plans are determined for both critical and representative events and are used to support emergency management decisions when an event occurs. Considering the unique characteristics of every contamination event, improvisations are performed during an emergency using adaptive models.

One of the critical public safety roles for water distribution systems is suppression of urban fire events, and fire safety is a major concern for infrastructure and emergency response planners, managers, and regulators. Due to the interdependency of water systems and emergency services, water utility managers should design and manage a water distribution system carefully to mitigate consequences associated with urban fire events, through actions and decisions that may reduce threats to property and public health. One approach to mitigate urban conflagration may be through redesigning water distribution infrastructure to improve fireflows, and potential designs for new pipelines can be selected based on the costs of redesign and the reduction of threats to the water distribution system. A set of important dynamics and interactions between water distribution systems and fire response systems influence the performance of fire suppression strategies and should be considered in planning and management for both systems. Most existing fire spread and suppression models for disaster planning and management consider firefighting demands as static parameters. While a few have modeled the interconnection between water system and fire response, those, however, have not addressed the dynamic linking between the two infrastructures. Additionally, existing fire spread models may oversimplify the realistic fire spread process. A novel framework that dynamically interconnects water distribution and urban fire spread models can aid decision makers in developing disaster management strategies. A cellular automata (CA)-based fire spread model is developed in this research to simulate the gradual spread of fire in large urban areas. The CA-based fire spread model will be coupled with a water distribution system's model to capture the dynamics of urban conflagration, emergency response, and water distribution hydraulics. This framework will be used to generate strategies to improve water distribution systems' fire fighting capabilities through dynamically opening hydrants and enlarging pipe sizes. This methodology will be applied to a hypothetical case study of an urban water distribution system to explore possible fire mitigation strategies.

Sentinel coupon devices may be installed in water distribution systems for decontamination surveillance. They give the possibility to extract samples and perform off-line laboratory analysis. The objective of this research work is to develop a concept for positioning sentinel coupons and sensors at representative and indicative locations in the water distribution system. A new integer linear programming formulation is proposed that is a weighted maximum coverage problem with weights that favor places where contaminant concentration is higher and the shear stress is lower. Extended period simulation models as contamination events are used inside a Monte Carlo simulation to calculate the averaged weights and the coverage matrix. The method was validated in a case study from the literature and applied to larger complex and detailed networks. The solution looks to favor sink nodes with long water paths. Finally, this new optimal placement problem was found to yield solutions that are significantly different from early-warning designs.

It is estimated that 15-40% of water is unaccounted for in urban water systems. This is mostly caused by small leaks, which are difficult to locate. Routinely measured pressure, flow, and water quality data can be used to locate leaks in the water network using an inverse modeling approach. For a known sensor configuration, the leak locations can be found by minimizing the difference between real and simulated measurements. However, when comparing measurement types (pressure, flow, or quality), some may be more sensitive to leak location than others. Furthermore, some measurement types may be more or less sensitive depending on the leak magnitude or the proximity of the leak to the sensors. The measurements types that are more sensitive to location will have a stronger signature and would need to be weighted more in an inverse modeling approach, especially in the presence of noise. Preliminary research suggests that water quality measurements are more sensitive to leak location when a leak is small, and that flow measurements are more sensitive when a leak is large. In this research, a series of sensitivity analyses are conducted on different networks to investigate the sensitivity of these measurements with respect to leak location, magnitude, and proximity of sensors to the leak location.

Water distribution systems are one of the most vulnerable civil infrastructures having crucial consequences on public health and the environment. Degradation of water quality in the distribution system farther away from the treatment plant may occur as a result of intentional or unintentional events, such as microbial growth within the pipes and injection of hazardous contaminants at system's cross-connections. It has been agreed that a key component in contamination warning systems is real-time monitoring of water quality using online sensors, which can provide an earlier indication of a potential contamination incidences. Most work related to placement of such sensors relies on available and well-calibrated hydraulic and water quality models (e.g., EPANET) integrated with optimization techniques (e.g., MIP, GA). In reality, these well-calibrated simulation models are rarely available from water utilities and typically include only partial information such as network topology and representative demand loadings. This work adopts algorithms from graph theory to suggest the location of sensors in a water distribution system given accessible information. The proposed approach can provide a more realistic decision support to water utilities in real application.

The presented model features a decision support system that alerts for contamination events in water distribution systems. The presented model is composed of an inner weighted SVM classifier, recognizing outlier's measurements, and a framework of sequence analysis optimization for the classification of events. The SVM enables a simultaneous analysis of the multivariate data, in a high-dimensional space, differing from the one-dimensional parallel analysis that was conducted so far. A weighted SVM is used for blurring the difference between the two class sizes and dealing with the time factor attribute. The time decay factor gives higher weight to the more recent observations. All of the parameters in the model are data driven determined by enumeration and optimization. The classifier is updated constantly and exploits an increasing database. The model was applied on a real WDS data with randomly simulated events superimposed on the original measurements and showed promising results.

The study of urbanization, and the water distribution networks that supply water to urban areas, has led to new approaches for evaluating the distribution systems that serve residential subdivisions. The present study aims to expand the evaluation method commonly applied by using genetic algorithms to add the actual hydraulic constraints required by Tucson Water in Arizona to an optimization model. Furthermore, an alternative calculation method utilizing a heuristic preoptimization tool coupled with a greedy algorithm is compared with the genetic algorithm results. The improved model is capable of achieving a near optimal solution, one that is comparable to the genetic algorithm results and should minimize the cost of constructing and operating a water distribution network. Preliminary results show that population density has little effect on the total cost and that area is the driving factor in cost. In addition, the slope increases the rate at which these two parameters increase the cost, making high-density areas much more cost effective with respect to the operation of water distribution systems. Finally, the main assumption, which considers residential subdivisions as rectangular networks, is explored by comparing the generated networks against their realistic counterparts. Results showed that the realistic networks cost more than the generated networks.

Achieving an optimal design for a typical water distribution system (WDS) essentially involves determining which combination of pipes and arrangements will produce the most efficient and economical network. Solving the problem is a complex process, one well suited to computationally intensive heuristic methods. Including water quality constraints can pose a special challenge due to the demanding, extended-period simulations involved. Employing artificial neural networks (ANNs) can reduce the amount of computation time needed. ANNs can in fact approximate disinfectant concentrations in a fraction of the time required by a conventional water quality model. This study presents a methodology for improving the accuracy of ANNs applied to the optimal design of a WDS by means of a probabilistic approach based on the fast finding of a network similar to the optimal WDS. This work also presents a methodology to find such a network. ANNs trained with the probabilistic dataset generated using the proposed approach were shown to be more accurate than their counterparts trained with a random dataset.

Recent developments in wireless/wired sensor networks allowed the application of stationary sensors capable of continuously collecting and transmitting hydraulic and water quality measurements at fine temporal resolution. The constantly updating data allows achieving an improved representation of the system state, modeling, and control. The deployment of fixed water quality sensors in water distribution systems has been recognized to be the key component of contamination warning systems for securing public health. This study proposes to explore how the inclusion of mobile sensors monitoring for various water quality parameters (i.e., pH, water hardness, and disinfectant) can enhance water distribution systems security. Mobile sensors equipped with sampling, sensing, data acquisition, wireless transmission, and power generation systems are being designed, fabricated, and tested with prototypes expected to be released in the very near future. Ideally, these mobile sensors will act as mobile agents capable of continuously conducting multivariate measurements and reporting them as they are distributed with water pipe flow. This work initiates the development of a theoretical mathematical framework for modeling mobile sensor movement in the water distribution system, processing and integrating the sensory data collected from stationary and nonstationary sensor nodes to increase system reliability and security through increasing coverage and reducing fault detection time.

Water distribution systems provide water supply to meet the people's demand, and it is an essential part of society. But it is also vulnerable and easy to get contaminated. Widespread contaminant can be introduced in water distribution system through accidental (e.g., rupture of water infrastructure, pipe leakage) or intentional (e.g., terrorist) acts. As a measure of water distribution contamination, the chlorine residual concentration can be used. The chlorine residual will highly decrease when a contamination happens in water distribution system. The objective of this paper is to develop a SRIQ (System Readiness Index for Water Quality) to evaluate and quantify the impact of widespread contamination on a water distribution system. The system is an expansion of a real WDS. It contains two reservoirs, four pumps, 78 pipes, and other needed fixtures. For assessment of system performance in widespread microbial contamination, EPANET software is used and SRIQ is calculated. SRIQ is predicted based on the combined assessment of water quality reliability, resiliency (time it takes to recover from a contamination), and vulnerability (how significantly the contaminant can damage the system) utilizing MATLAB toolbox. The impact of providing redundancy in pipes and reservoirs to increase the systems' reliability is also investigated. The results of this study can be utilized for improvement of water distribution systems performance.

The objective of the least cost design of a water distribution system is to find its minimum cost with discrete diameters as decision variables and hydraulic controls as constraints. The goal of a robust least cost design is to find solutions that guarantee its feasibility independent of the data, i.e., under model uncertainty. Typically the uncertainty of the model is assumed to be in the consumers' demands, as opposed to its reliability being computed based on violation of hydraulic heads, resulting in an implicit inclusion of the uncertainty in the optimization model. In this work, uncertainty in the demand is accounted for through explicit formulation of the demands in the mass, head-loos, and minimum head constraints. A robust equivalent (Ben-Tal and Nemirovski, 1998, 1999) incorporating the uncertainty is formulated and solved to optimize the design or rehabilitation of water distribution systems. Explicit uncertainty formulation and tractability of the problem is accomplished through linearization of the head-loss equations for the description of the robust equivalent approach. The uncertain data is described by deterministic ellipsoidal uncertainty sets with a predefined size determined by the decision maker reflecting risk aversion and providing a trade-off between robustness and performance. This work demonstrates the structure, tractability, and flexibility of robust optimization to water distribution systems least cost design.

As water infrastructure ages and repair costs increase, optimization techniques are increasingly used for the design and operation of water networks. A key challenge for optimization of water systems is the fast and accurate simulation of hydraulic equations. Conventional simulation tools such as Epanet are fast but cannot perform optimization alone and so must be coupled to an optimization engine, typically a meta-heuristic such as a genetic algorithm. In contrast, mathematical optimization methods take into account hydraulic equations as constraints. The energy equation for pipe flow is a challenging constraint because it is non-linear and given by an explicit function with a rational exponent (Hazen-Williams) or an implicit function (Colebrook-White). This paper uses a quadratic approximation for pipe head loss that provides very good accuracy. The approximation is applied to pose and solve a mixed integer non-linear program (MINLP) for placing and setting pressure-reducing valves. The problem is addressed using both local and global solvers. Computational results show accuracy comparable to Epanet and significant potential to reduce nonrevenue water by deploying optimal solutions.

The city of Kingston, Ontario, is currently experiencing elevated costs to repair its aging buried water main assets. The application of a predictive water main break model allows for the estimation of pipe condition and likelihood of failure. The objective of this paper is to develop a generalized linear model (GLM) and artificial neural network (ANN) model to forecast pipe breaks in the Kingston water distribution network. Data supplied by Utilities Kingston was used to develop the predictive water main break models, incorporating multiple variables, data history, calibration, and data prioritization. The goal of these models is to provide a practical means to assist in the management and development of Kingston's pipe rehabilitation program and to enable Utilities Kingston to reduce water main repair costs and to improve water quality at the customer's tap. Models with acceptable precision will produce a reliable decision tool for future planning and budgeting.

This paper presents a generalized methodology and implementation aimed at surrogating the extended period hydraulic simulation with Artificial Neural Networks (ANNs) for a large water distribution system. Each snapshot of the hydraulic simulation is modeled as a set of input-output relationships, replicated by a collection of ANNs trained on the commodity graphics processing unit (GPU). Previous research by the authors on a particular demand-monitoring zone (DMZ) system with the limited hydraulic properties is generalized to include a comprehensive account of state variables, and their dependencies are captured by a systematic sensitivity analysis that guides the modular assembly of multi-ANN meta model. The trained networks are validated for successive calls over extended periods of time (as long as a week), and tremendous improvements in terms of accuracy and reliability are obtained and compared with the results in previous publications. The improved meta model manifests as a powerful tool for fast and accurate hydraulic response prediction for operation optimization.

The Water Sector Research and Development Working Group has stated that water utilities would benefit from a clearer and more consistent understanding of their system flow dynamics. Understanding flow dynamics is important to interpreting water quality measurements and to inform basic operational decision making regarding the distribution system. Because these models will be used in decisions that involve significant investment and potential impact to the community, it is important that the model be an accurate representation of the actual conditions in the system. However, creating a hydraulic model of a water distribution system of any size comes with many difficulties, as many engineers can attest. Modeling smaller systems, such as the one in this study, is simpler from an engineering perspective but the challenge comes from the amount and quality of the information necessary to produce accurate results. For this model calibration we overcame issues such as collection of boundary condition data without a SCADA system, a 40% water loss due to system leaks and lack of system geometry data such as tank stage/storage curves, hydrant elevations, and valve closures. This study examines the use of data from hydraulic testing, especially C-factor and fire flow tests, and other collection methods to gather information about the system and calibrate a model for a small utility. Calibration was performed using the PIPE2010 program by KYPIPE, LLC.

Hydraulic modeling is now commonly used to help engineers to design pump stations and water transmission/distribution systems. In this paper, a case study of a Somerset water system elaborates how to modeling programs and tools to size pumps and distribution networks. The Somerset water system is proposed to provide drinking water from the to-be-upgraded Somerset pump station to its serving areas including three different pressure zones: 830, 730, and 790. This project is a part of the San Antonio Water System's (SAWS) district special projects and upgrades to the facility are necessary to support integration of the pump station into the SAWS network. This system includes, but is not limited to, the Somerset pump station and water distribution network including ground and elevated storage tanks. The system has a design capacity of 5.441 million gallons per day (MGD) representing the maximum hourly demand of the system. Five steady state scenarios are evaluated to develop system head curves and hydraulic modeling data needed for sizing the new Somerset pump station: (1) 2017 maximum hour demand (MH); (2) 2017 maximum hour demand + fire flow (MH+FF); (3) 2017 maximum daily demand (MD); (4) 2017 MD with the lowest water level at the Somerset Pump Station Ground Storage Tanks (GST) and the highest water level at the highest elevated storage tanks (high end of the system head curve); and (5) 2017 MH+FF with the highest water level at the Somerset Pump Station ground storage tanks (GST) and the lowest water level at the highest elevated storage tanks (low end of the system head curve). In addition to meet year 2017 flow requirements, other constraints were listed below per the SAWS Water System Modeling Standards and Practices: (a) for 2017 MH scenario, the minimum pressure should be 35 psi, and (b) for 2017 MH+FF scenario, the minimum pressure should be 25 psi. Based on the hydraulic modeling results and generated system head curves, the recommended design duty point for the four new Somerset Pump Station pumps is 1.813 mgd = 1259 gpm, 270 ft. The 2017 MH scenario minimum pressure will be 37.376 psi (>35 psi as required by SAWS standards) and the MH+FF scenario minimum pressure is 26.255 psi (> 25 psi as required by SAWS standards).

Often, parameter estimation is not the only focus of a calibration process. The final aim of the calibration process is to use the estimated parameters for accurate model predictions. It is understood that the estimated parameters with higher uncertainty will poorly predict the system. For a nonlinear high-dimensional system like a water distribution system, point estimation of the model parameter is not adequate. It is important to identify the confidence intervals of the estimated parameters for such a system. A parameter may be estimated but it may not be identifiable for the set of data collected. The profile likelihood based confidence interval can be used to analyze the identifiability of the parameters. Confidence intervals for three-wall decay parameters in the water distribution systems were calculated from profile likelihood using chi-squared distribution in this paper. Results show that additional field data may be required for a parameter to be completely identifiable.

A burst in a water distribution system (WDS) results from the pipe rupture resulting in loss of water and disruptions to customer service. Rapid burst detection increases resilience by reducing the time to identify that a break has occurred to isolate the failed pipes and to recover service. This study compares three univariate and three multivariate Statistical Process Control (SPC) methods with respect to their detectability. The univariate SPC methods are the Western Electric Company (WEC) rules, the Cumulative Sum method (CUSUM), and the Exponentially Weighted Moving Average (EWMA) method, while three multivariate methods are Hotelling T2 method and the multivariate versions of CUSUM and EWMA. A method's detectability is determined by detection efficiency and effectiveness. To test the methods, nodal pressures and pipe flow rates were generated from a real hydraulic model and detectability is computed for flow and pressure meters in alternative configurations.

In the present work is the simulation tool by EPANET, the flow in a water distribution network of São Lourenço-MG, Brazil and after the simulation was performed to calibrate the distribution network. Was used to calibrate the library Galib. Some initial results of this research are presented in this paper. The results showed good fits between simulated and measured pressure and flow. The calibration results in the case of roughness on the network led to more reliable simulation.

A utility manager may become aware of a threat of contamination to a water distribution network through water quality sensor information, which may indicate that a biological pathogen or chemical contaminant was introduced to the network. In response, a utility manager can select a set of hydrants to flush contaminant from the network. As an event unfolds, a decision maker may not be able to ascertain source characteristics, creating additional difficulties in determining the set of hydrants that should be opened. The research presented here develops a Genetic Programming (GP)-based approach to identify a set of response actions that are based on sensor information, instead of source characteristics, for guiding selection of hydrants. GP is a method within the class of evolutionary computation, and a solution is represented as a combination of values and symbols to represent a computer program for executing computations, such as a mathematical equation. GP is developed in this research to program a list of rules for opening and closing hydrants that will effectively protect public health for an ensemble of contamination events. An ensemble of contamination events is developed based on a set of similar activated sensors. As the public health effects of a contamination event are influenced by a set of complex interactions among consumers, utility operators, and the pipe network, an agent-based modeling framework is used to predict the dynamic location of a contaminant plume during a contamination event and the number of exposed consumers. To identify optimal hydrant strategies to flush a contaminant while considering the complexity of interactions in the system, a simulation-optimization model couples agent-based modeling with GP. Multiple contamination scenarios are modeled to evaluate potential solutions, and the simulation-optimization framework is demonstrated for a virtual mid-sized municipality, Mesopolis.

Modeling and SCADA (Supervisory Control and Data Acquisition) systems can work together to provide better insights into water systems performance than either can alone. This paper describes the benefits and associated impediments to such a relationship as these two types of systems were not created to work together. Considerable progress has been made in bidirectional sharing of data between SCADA systems and models as data can be imported into models, models can be run from within a SCADA Human Machine Interface (HMI), and results can be viewed in either the HMI or model.

Security is an important concern for the water industry nowadays. It is particularly important to have tools that are able to determine the source of contamination once an alarm is raised by the sensor detection system. The objective of this paper is the development of such a model to locate potential sources of contamination. The model solution uses a two-step method. First, a linear source-response transport equation is built based on a backtracking algorithm applied to sensor binary answers. It is followed by a minimum relative entropy method or a least squares method coupled with a Tikhonov regularization that yields the probability density function of the different potential sources found at the first step. The model has been validated on small networks and applied to a large network under single and multiple contamination scenarios. This research is part of the European project on water network security named SecurEau.

Leak detection and management is an important problem in water distribution systems because it has been documented that up to 40% of the water may be lost to leaks in many aging systems. Small gradual leaks, which represent more than half of all leaks, are difficult to locate. Routinely measured pressure, flow, and water quality data in combination with a simulation-optimization inverse modeling approach could be used to characterize leakage. In this approach, the leak locations are found by minimizing the difference between real and simulated measurements for a known sensor configuration. Simulation-optimization approaches are computationally demanding because millions of simulations of a network simulator (e.g., EPANET) may be required to achieve a satisfactory solution. This problem is alleviated using a high-performance computing (HPC) framework that enables many parallel simulations of the water system using EPANET. This research is modifying an existing global search algorithm, called the Dividing Rectangles (DIRECT) Search that is traditionally used for continuous functions to enable parallel simulations and a mix of discrete variables (for leak locations) and continuous variables (for leak magnitudes). The modified algorithm is being tested with traditional continuous test functions, discrete test functions, and test water distribution networks.

The field of optimal water system operation is well explored. Minimal cost system operation depends upon several factors, mainly the following: consumer water balance constraints, minimal or maximum water head constraints at system nodes, and minimizing leakage and pump station energy consumption, which is dependent on the pump stations varying total head. The above factors have a nonlinear relation to the flow variable and are commonly solved using timely nonlinear techniques such as MIP, NLP, or heuristics. This study utilizes an iterative linearization technique to iteratively linearize the problem and solve each step using linear programming. The methodology is demonstrated on an illustrative example.

Water distribution piping has a useful life on the order of a century while pipe-sizing decisions are usually based on a planning horizon on the order of 20 years. Because of the substantial economy of scale in pipe sizing and the long useful life, there may be benefits to installing piping with some excess capacity in the short term depending on expected long-term growth. The analysis presented in this paper shows the value in considering long-term growth in demand even if the planning horizon for the study is much shorter. While the only decision that needs to be made in the current year is the size of the initial pipe, it is important that the pipe fits into a long-term plan for the distribution system but the exact diameter doesn't make much difference.

The presented study features a multiobjective optimization model that aims to achieve the best tradeoff between low cost and high reliability of a water distribution system design. The algorithm is novel in merging the use of Genetic Algorithm (GA); features an effective exploration of the search space, with the so-called "split pipes" method; and enables the use of more than one diameter for each pipe section. This was achieved by a new formulation that takes advantage of a theoretical old finding that multidiameter pipes, if they exist in a solution, comprise at most two adjacent discrete pipe diameters. The method was applied on the well studied problems of the two-looped and Hanoi network and achieved the best known least-cost design solutions. In addition the study presents an interesting insight regarding the resilience measurement. Analysis of the system response to diverse failure cases (involving demand increase and pipe breakage) showed that an improvement in resiliency does not necessarily imply a reliability improvement.

This paper presents an approach that combines concepts of energy use and the ILP to find near-optimal solutions for the optimal design of pipes in series systems in a reduced amount of time. The proposed methodology predefines the head in each node based on known criteria developed by past research on optimal design of looped demand-driven networks. Once the heads are available, the demands are calculated with the demand-pressure function and then the problem is solved as demand-driven with ILP. Taking into account that the resulting design can be unfeasible because of the probable changes in the nodes' heads and therefore in the demand flows, there are needed various iterations of the methodology that explore the head assignation space in an intelligent way. The methodology is tested for different scenarios showing the advantages of this approach.

This paper describes a new approach given to the Optimal Power Use Surface (OPUS) methodology, which consists of the decomposition of a water distribution system (WDS) into an open tree-like structure (a spanning tree). Once the sumps in the model are identified, integer linear programming (ILP) is used to accelerate the design process, calculating the diameter of every node in the tree. This is achieved by focusing on setting up efficient ways to dissipate energy and distribute flow. The tree structure is built starting from the water sources. Then, the rest of the tree is assembled adding adjacent pipe-node pairs, one at a time. The methodology is tested on three benchmark problems (Hanoi, Balerma, and Taichung). When compared with results obtained through other methodologies, this new approach stands out for allowing designs with construction costs very similar to those obtained in previous works but requiring a number of iterations several orders of magnitude below. The methodology proves that following hydraulic principles and applying ILP is an excellent choice to obtain low-cost WDS designs, with very little effort, and provides an alternative path to the tiresome search process undertaken by metaheuristics.

Coal tar and bitumen have been historically used to coat the insides of cast iron drinking water mains. Polycyclic aromatic hydrocarbons (PAHs) may leach from these coatings into the drinking water and form a potential health risk for humans. In a Dutch nationwide study we took drinking water samples at 120 locations over a period of 17 days under various operational conditions, such as undisturbed operation, during flushing, and after a mains repair, and analysed these samples for PAHs. During flushing, PAH levels frequently exceeded drinking water quality standards. After flushing, these levels dropped rapidly. After the cut and repair of cast iron mains, PAH levels exceeded the drinking water standards for up to 40 days after the repair. We estimated the health risk associated with an exposure scenario over a lifetime period. The margin of exposures of PAHs through drinking water are well above 10,000 for all 120 measurement locations under the cautious assumption of relatively long exposure times. This indicates that PAH exposure through drinking water is of only low concern for consumer health.

This paper presents the development and performance testing of the parallelization scheme for executing water distribution system analysis solvers. Using multithread computing techniques, hydraulic and water quality simulations are parallelized in two separate threads. One thread noted as H-thread is assigned to perform hydraulic simulation while the other thread noted as Q-thread is to undertake water quality analysis. Q-thread proceeds once H-thread completes the hydraulic simulation for one time step. To ensure that Q-thread consumes the correct hydraulic results for water quality analysis, both threads are synchronized such that H-thread is always ahead of Q-thread over the simulation period. The hydraulic simulation results within a dynamic time window are stored in memory, instead of writing to a temporary file, thus the parallelization scheme further streamlines the water quality analysis by eliminating the retrieval of the hydraulic results from the temporary file. The implemented parallel simulation solvers have been tested on a number of large water distribution models, the results show that consistent speedup has been achieved.

The optimal design of a water distribution system under worst-case transient loadings is formulated as a two-step optimization problem. In the first step, particle swarm optimization is used to identify the set of critical nodes that will result in the worst case transient loading condition. In the second step, dual-objective optimization is used to determine the optimal pipe sizes that simultaneously minimize cost and the likelihood of damaging transient events, measured by a parameter called the surge damage potential factor. Nondominated sorting genetic algorithms are combined with transient analysis to produce a set of Pareto-optimal solutions in the search space of pipe cost and surge damage potential factor. The case study tested on the New York tunnel system confirmed that pipe size is a significant factor in controlling transient response. It is concluded that transient consideration in the design phase, in conjunction with conventional least-cost pipe size optimization, will help water utilities achieve a high degree of hydraulic integrity and reliability and extend the life of their distribution systems. Enhancement of water distribution system planning and management is a principal benefit of the proposed methodology.

This study attempts to develop a resilience-based recovery model of water supply system against earthquake events. Our objective is to sequence repairs to maximize system restoration through water delivery to critical locations or to maximize the number of served customers in the shortest time period given multiple failures. For these purposes, a computer simulation model can be helpful in examining restoration strategies in a risk-free and virtual environment under a range of possible emergency scenarios. Therefore, the goal of this study is to examine the effectiveness of key restoration strategies for emergency preparedness plans. Furthermore, it is envisioned that this simulation model can be used in conjunction with other pre-event and/or post-event loss reduction strategies for the design of robust and resilient water supply infrastructure and optimization of restoration strategies. The proposed methodology depicts the real-life restoration process that can be used by planners, engineers, and decision makers to better serve the community.

The impact on household level water demand is evaluated in four California cities while undergoing a transition from uniform to tiered rates. Price elasticities for the time periods under uniform and tiered rates are determined individually using panel data regression methods. Price elasticities in Bear Gulch, Palos Verdes, South San Francisco, and East Los Angeles ranged from -0.09 to -0.22 under uniform rates and -0.12 to -0.532 under tiered rates. Theoretically, tiered rates maintain affordability for all users while compelling high users to reduce through increasing marginal prices for higher quantities of water. Evaluating the effects separately on low-income users, water patterns of eligible customers who took advantage of a rate assistance program were compared. Low-income discounts did not have a significant effect on water consumption patterns and only had a small difference in price elasticities compared with nonparticipants.

Mounting a fast and effective response if contamination enters a drinking water distribution system is important. A significant part of any response is identifying the source of contamination. In previous work adjoint methods have been successfully employed for this task. Adjoint methods use system sensor data as inputs into adjoints of forward transport equations to backtrack information through a water distribution system to probabilistically determine the source of contamination. Previous work has assumed complete mixing at pipe junctions. This is not the case in a real-world distribution system leading to discrepancies between the modeled system and the true system. A bulk advective mixing algorithm (EPANET-BAM) has been developed to introduce more realistic mixing at pipe junctions. We develop adjoint theory incorporating incomplete mixing at the pipe junctions and test it using EPANET-BAM.

A panel data regression model was developed to evaluate the impacts of metering on household water consumption. Three California cities were evaluated after undergoing metering for the first time, while concurrently being switched from flat to tiered rates. Metering is generally recognized to reduce water use, but the actual usage depends on various factors. Those factors were additionally investigated and effects were compared with households that were previously metered. Covering a two-to-three-year period, monthly household water use reduced after metering and facing a price rate change by 54 gpd in Bakersfield, 36.5 gpd in Chico, and 12.9 gpd in Visalia.

Resilience is defined as the ability of a system to limit the impact of a disturbance and to return to its full functionality after a disturbance. Resilience is becoming a distinct topic in several different fields of research, but it has yet to be implemented in water resources and in particular to regional water supply systems (RWSS). According to Bruneau et al. (2003), resilience is a function of the loss of system functionality and the duration of a failure event. The loss of functionality is related to the redundancy and robustness of the system while the recovery time is a function of system resourcefulness in developing and the rapidity of responses. As failure likelihoods and recovery times in RWSS are difficult to assess, this paper focuses on redundancy and robustness and the internal dynamics of the underlying RWSS while it is impaired. To that end, a linear programming (LP) flow allocation model is employed. The model represents a portion of the Tucson metropolitan area and was designed to be adaptable so that it can be applied to a general RWSS. The model determines the optimal flow allocation within a RWSS that minimizes cost. Greenhouse gas production and energy consumption are computed as secondary outputs. Various infrastructures were modeled by adding satellite waste water treatment plants (decentralization) in different locations to compare with a centralized system. RWSS resilience is measured as the volume of water that is not delivered to users (shortages) for several infrastructure failure scenarios. Results were compared between various system configurations to identify the most resilient system structure and critical infrastructure components that affect system resilience.

This study develops a system-robustness assessment model of water supply infrastructures against earthquakes. For this purpose, repetitive probabilistic simulations are performed to examine relative importance of system components under possible seismic scenarios. Monte Carlo simulation (MCS) is used for the probabilistic seismic simulations. Seismic damages are quantified using several robustness indices such as system serviceability, nodal serviceability, and water availability. The proposed methodology is applied to a real network in South Korea using historical seismic information. The proposed model can be used in earthquake-resistant system design to strengthen system durability and minimize potential damages.

Most urban distribution water mains are located under paved streets or roads. Despite an obvious interdependence between pipe and pavement deterioration, this interdependence has not yet been considered in frameworks that would optimize both simultaneously, which is the issue addressed in this paper. The deterioration processes of both pipe and pavement are considered to be deterministic, and some assumptions are made about the interactions between pipe breakage frequency and pavement condition. Total life cycle costs of both pipe and pavement are computed as the discounted costs of an infinite series of perpetual renewal cycles. Genetic Algorithm (GA) is used to find the (near) least cost strategy for scheduling multiple pipes and pavements in a network.

It is important to identify the source of contamination in a drinking water distribution system to discontinue the event and determine ways to prevent future contamination from entering the system. Previous work has demonstrated the effectiveness of an adjoint method using contaminant concentration measurements from system sensors to probabilistically determine the source of contamination in a drinking water system. The method can be applied in systems with either steady-state or transient hydraulics. The method uses publicly available software (EPANET) coupled with a particle backtracking model (BTX) and a conditioning method to probabilistically identify the contamination source and release time. Prior work assumed perfect sensors capable of measuring the exact concentration of contamination. In this work the method is enhanced to account for measurements from more realistic, nonideal sensors that identify the range of contamination at the sensor (e.g., high, medium, low), rather than the precise concentration. In addition, the method is augmented to use nondetectable measurements, i.e., sensor measurements for which the measured contamination is below the limit of detection.

The distribution networks of water supply are fundamental structures in the urban environment; however, it is necessary studies on water losses that are significant in many countries. For this it is necessary to study a system with an initial diagnosis, representing data collection among the sanitation companies and field inspection. The monitoring is performed mainly on information flow and pressure, to leave for the application of mathematical models and simulation. However field campaigns are expensive and need to optimize the points to be measured. In this work we applied an algorithm based on entropy theory to determine optimal points. The application was made in São Lourenço, Minas Gerais, Brazil. The results were considered good because it works for calibration.

Public health protection and the provision of potable water are main priorities for all drinking water utilities. Over the last 10 years, the threat of contamination of the nation's drinking water infrastructure has heightened utility awareness of distribution system security. Drinking water systems face enormous challenges in meeting these goals, and in particular, small water systems, which comprise 94% of the nation's public water systems, face additional economic and operational hurdles. The CANARY event detection software was developed to enhance the detection of contamination in water distribution systems. Working in conjunction with a network of water quality sensors placed strategically throughout the distribution system, CANARY increases the likelihood and speed of detection by interpreting sensor data in near real time, identifying anomalies and alerting the operator when a contaminant might be present. Through pilot studies, CANARY has demonstrated its ability to detect unexpected "normal" events, such as sensor malfunctions or pipe breaks. This study systematically investigates how CANARY could be used to provide multiple benefits to water utilities by improving water system operations, treatment, and security. The probable causes of standard distribution system water quality issues (e.g., maintenance of an acceptable disinfectant residual, biofilm control, customer concerns) are presented and the associated changes in water quality parameters that could be detected by CANARY. The range of conditions under which CANARY could detect each of these water quality issues is evaluated. For water utilities of all sizes, the value of using this type of detection software to enhance detection and response to a wide range of water quality events is discussed.

Water distribution modeling for hydraulics and water quality is an important tool for managing system performance of water utilities. Numerical models of water distribution systems have limitations in modeling real systems. A water distribution system was constructed at the University of Kentucky hydraulics lab for the purpose of investigating the performance of water distribution models. The model contains numerous hydraulic (pressure, flows) and water quality sensors for measuring travel time of a conservative tracer and can be run with unlimited configurations. This report presents a case study illustrating the results of a hydraulic calibration using both hydraulic data in terms of pressure head, water quality data in terms of travel time estimates from electrical conductivity sensors, and combinations of both. It also presents, in a case study form, an example of a small experimental system where velocity data as a basis for a calibration effort and pressure-based data as a basis for calibration effort do not converge to the same solution. Thus some engineering judgment, above purely quantitative basis, was required for optimal system calibration.

Event detection is currently one of the most challenging topics in water distribution systems analysis. The problem is related to how regular on-line hydraulic (e.g., pressure, flow) and water quality (e.g., pH, free chlorine, conductivity, oxidation reduction potential, temperature) measurements can be efficiently utilized to designate a contamination occurrence. To date all experiments on testing event detection models are based on generating arbitrary manipulations of water quality parameters (e.g., through utilization of Gaussian probability density functions). Employment of such an approach is on the one hand generic, but on the other has no physical connection to the water distribution system's physical behavior. In fact, all event detection models to date for water distribution systems do not take advantage of the hydraulic/water quality understanding of the system in the decision process of event detection. This study describes some initial steps of utilizing EPANET-MSX for generating test contamination scenarios aimed at more realistically validate event detection models through complex contamination events simulation modelling.

Contamination warning systems involve a network of sensors that can assess the water quality in a water distribution system and alert an operator of a potential contamination event. Utilities developing these water quality monitoring systems are faced with the decision of what locations are best suited for deployment of these sensors to maximize their ability to detect contamination events. TEVA-SPOT is a sensor placement software tool that uses an optimization algorithm to evaluate the hydraulic model of a system and recommend optimal locations for water quality sensor deployment. This paper presents a study in which several systems were investigated using the TEVA-SPOT software. A database of distribution system models of small utilities was first created to support this research. Models were then used in the TEVA-SPOT software and input data such as contamination scenario, number of sensors to be deployed, and sensor design objective were then assigned. The locations recommended by the software as optimal sensor locations were evaluated and investigated for patterns as compared with other systems. Each sensor placement recommendation was analyzed to determine the proximity of the sensor locations relative to one another and evaluated in terms of the need for additional sensors. Results of the sensor placement evaluation were grouped by system configuration, and trends were examined based on loop, grid, or branch configuration. The results of this study indicated that 50 to 75 percent of sensor designs had the two sensor locations placed close together for the loop and grid systems, respectively. However, no sensor designs had two sensor locations placed close together in the branch systems. These same trends were reflected in the need for additional sensors.

PWN strives for as few water quality complaints as possible. There is a strong interest in understanding the fouling mechanisms and finding a more long-term solution to reduce the brown water complaints. Therefore PWN records the turbidity of all their flushing actions. In this paper 30 turbidity datasets of low-flow flushing actions over a period of 18 months were analyzed in two ways. First, the sediment accumulation rate of the total network was analyzed and second, the locally accumulated material per pipe was studied. The hypothesis is that the location and amount of sediment accumulation may be related to temperature, the location of branches and appurtenances, and the maximum flow velocity. The results show that temperature is an important factor for sediment build-up in the study area; accumulation rate increased with higher water temperature. The location of branches in mains may or may not play a role. It seems that more sediment is accumulated around the branches (both before and after the branches). The influence could not be quantified as the branches are relatively close to each other. The influence of maximum flow velocity could not be determined in this relatively small study area.

Climate change, a result of the accumulation of greenhouse gases in the atmosphere primarily from the combustion of fossil fuels, may influence public health in innumerable ways including a risk of increased frequency and intensity of heat waves; reduction in cold-related deaths; increase in extreme weather events; changes in the distribution of water-, food-, and vector-borne diseases; and a risk of malnutrition, especially in the poor. These combined effects negatively affect public health (Haines, Kovats, Campbell-Lendrum, & Corvalan, 2006). In contrast, an improvement in public health requires much input of natural and human-built resources, which should raise the emissions of CO2 even more and thus result in an increase in global temperature. Based on this interaction between climate change and public health, a semi-empirical model was built. After that, the model was calibrated with data collected between 1901 and 1960. During the calibration, climate change was represented by global average temperature while public health was represented by life expectancy at birth. Finally, the calibrated model was validated with data from 1961 to 2005. Agreement between the results and the observation data is remarkable, with almost all relative errors less than 6%. The model of climate change and public health can be used to predict trends in climate change and public health and also provide insights into strategies for controlling the rise in temperature and improving public health.

This paper proposes a statistical downscaling (SD) technique to link large-scale climate variables and annual maximum daily rainfalls (AMDR) at a local site. In particular, the proposed SD technique relates the AMDR to the standardized principal components (SPC) of the global climate variables, which are calculated using the robust and efficient technique of singular value decomposition (SVD). The proposal has been developed with two popular general circulation models (GCMs; HadCM3 and CGCM3) and available 41-year (1961 - 2001) AMDR data at six sites in the Chi and Mul River Basins (Thailand). Results have indicated that the SD method is advantageous over an accepted practice (SDSM) because its probability distributions of AMDR scenarios (HadCM3A2 and CGCM3A2) are accurate without making any correction.

Different studies around the world have proved that the mean sea level is rising globally in the last century. The flood plains are mapped to determine the extent of flood hazard and zoning for construction, coastal protection, and evacuation if needed. In this study, the mean high high and extreme water level in New York City is analyzed to determine how the current flood plain developed by FEMA and NOAA could represent the current hazard of 100-year floods. For this purpose the sea level rise data since 1920 up to 2012 are considered including the water level data during Irene and Sandy hurricanes. The results are employed to adjust the 100-year in New York City. The flood plain boundaries are determined, and the evacuation zones are developed and compared with the current 100-year flood plain map. Moreover, an aerial map was used in this study for better assessment of current and future vulnerabilities of coastal cities including New York City. The vulnerable stations and major financial and residential regions are identified, and some suggestions are provided to reduce their vulnerabilities. Some recommendations are provided for best management practices (BMPs) application to reduce flood risks and damages. This study shows that rising sea level and high storm surges, especially following hurricane Sandy, have caused the floodplain to shift inland and more efficient flood control measures are needed.

Internal modes of climate variability defined as teleconnections have known to have an effect on precipitation extremes relating to magnitude and frequency. Evaluation of influences of climate variability on storm event characteristics, especially the interevent time definition (IETD) defined by minimum dry period between storm events is the main focus of the study. Storm event totals, duration of the events, and interevent time (gap between any two events) are evaluated in this study for different values of IETD. Historical precipitation data available in the form of gridded spatially interpolation data is utilized for this study. Time slices associated with climatic multi-decadal Atlantic Multi-Decadal Oscillation (AMO) cycles or phases are used for the assessment of the variability of storm event characteristics. Gridded bias correction and spatial disaggregation (BCSD) precipitation data set from 1950-1999 at 1/8° spatial resolution for the state of Florida is used for the analysis. Preliminary analysis reported in this paper suggests interevent durations and precipitation depths (storm totals) are higher in AMO warm phase compared with those from cool phase when IETD is more than equal to three days. The mean value of duration between any two events decreased in the recent two decades. Spatial variability of storm totals is evident when these totals are compared from two phases.

Several statistical downscaling models have been developed in the past couple of decades to assess the hydrologic impacts of climate change by projecting the station-scale hydrological variables from large-scale atmospheric variables simulated by general circulation models (GCMs). GCMs have a good chance to capture the large-scale circulation patterns and correctly model smoothly varying fields such as surface pressure, but it is extremely unlikely that these models properly reproduce nonsmooth fields such as precipitation. This study compares five statistically downscaling models: multiple linear regression (MLR), positive coefficient regression (PCR), stepwise regression (SWR), support vector machine (SVM), and bias-correction spatial disaggregation (BCSD) for estimation of rainfall in the state of Florida, USA. The performance of the models is evaluated using various performance measures, and it was found that the SVM model performed better than all the other models in reproducing most monthly rainfall statistics at 18 locations. Output from the third-generation Canadian Global Climate Model (CGCM3) GCM for A1B scenario was used for future precipitation projections.

Survivability of aquatic organisms has been linked to stream temperature regimes. Climate change is anticipated to alter the current thermal patterns in riparian ecosystems and will have implications for these organisms. A water temperature change of 1 or 2 °C may have severe consequences for aquatic species, specifically coldwater fishes. Monitoring and modeling of stream temperature regimes is critical to assessing the vulnerability of coldwater species under the impacts of climate change in the Northeast United States. This research reviews the literature on existing stream temperature models for applicability over varying spatial and temporal scales. Collection of existing stream temperature data in the Northeast into one consistent format for analysis in stream temperature models is in progress. Other ongoing efforts include the evaluation of three models for effectiveness across a large spatial scale, the deployment of temperature loggers based on previous spatial stream network coverage with the purpose of coarse and fine-grain monitoring, and the application of models to basins in the Northeast to study climate change impacts on stream temperature and identify watershed characteristics that lead to resilient stream temperatures.

Understanding climate change impacts on hydrologic regime is important to evaluate water resources systems vulnerability and develop adaptation strategies. Traditional studies are complex and expensive. A recent and simple methodology, based upon Budyko's hypothesis and climate elasticity concept, allows estimation of sensitivity of long-term streamflow to changes in climate variables. This methodology was applied to the Upper Jaguaribe River basin, Brazil, wherein a traditional climate change impact study has been carried out. Results for the sensitivity analysis suggest that a 1% increase in precipitation results in a 2.75% increase on runoff, while a 10% increase in potential evapotranspiration results in a decrease of 17.3% in runoff. Comparison of these results with those obtained from a more traditional approach (statistical downscaling followed by hydrologic modeling) showed that estimates of relative changes in runoff are very similar, with errors within 0.06 and correlation of 0.99, suggesting that the methodology could be used in preliminary studies to identify the most sensitive basins that need more detailed studies.

The present study proposes a statistical downscaling approach to the assessment of the climate change impacts on the estimation of design storms and the resulting runoff characteristics for a given urban watershed. The proposed approach is based on a combination of a spatial downscaling method to link large-scale climate variables given by general circulation model (GCM) simulations with daily extreme precipitations at a site and a temporal downscaling procedure to describe the relationships between daily and sub-daily extreme precipitations based on the scaling general extreme value (GEV) distribution. The proposed method was tested using simulations from two GCMs under the A2 scenario (HadCM3A2 and CGCM2A2) and annual maximum (AM) precipitation data available at the Dorval Airport raingauge in Quebec (Canada). It was found that AM precipitations and design storm rainfall intensities downscaled from the HadCM3A2 displayed small decreasing trends in the future, while those values estimated from the CGCM2A2 indicated large increasing trends. Similar variations were found for the estimated runoff characteristics for several selected urban watersheds of different shapes, area sizes, and imperviousness levels. Results of this illustrative application have indicated the feasibility of the proposed downscaling method.

Under the umbrella of the IWA/IAHR Joint Committee on Urban Drainage, the International Working Group on Urban Rainfall (IGUR) has reviewed existing methodologies for the analysis of long-term historical and future trends in urban rainfall extremes and their effects on urban drainage systems, due to anthropogenic climate change. Current practices have several limitations and pitfalls, which are important to be considered by trend or climate change impact modellers and users of trend or impact results. The review (Willems et al., 2012) considers the following aspects: analysis of long-term historical trends due to anthropogenic climate change, analysis of long-term future trends due to anthropogenic climate change, and implications for urban drainage infrastructure design and management. A summary is provided in this paper.

A coupled flow and wave model, the Coastal Modeling System (CMS), was developed to simulate synthetic tropical storms with the consideration of future sea level rise (SLR) scenarios and to evaluate the potential coastal inundation at Naval Station Norfolk, Virginia. The CMS capability for surge and inundation calculations was validated with Hurricane Isabel, a devastating hurricane that landed on the Norfolk area in 2003. The CMS calculated water surface elevation and storm-induced inundation for combined influence of tide, surge, waves, wind, and SLR. Associated with the storm surge and SLR, extensive inundation occurs at the Naval Station Norfolk. For the 100-year storm, the surge levels could inundate approximately 60-80% of the Naval Station Norfolk under the present sea level and different SLR scenarios.

Engineering hydrology is primarily conducted using rainfall frequency atlases and return period design storms. Recent anecdotal experience has suggested that this method may result in extreme event estimates that are underestimates of actual events. In this research, 332 rain gauges covering the southeastern United States were analyzed for trends in the 100-year quantile estimate, using annual maxima values derived from daily precipitation data covering the past 79+ years. A nonparametric trend test was applied by use of a moving cumulative 100-year storm estimate calculated using the GEV distribution and confidence intervals generated by a Monte Carlo simulation. The results show about 40% of the stations exhibited some form of nonstationarity, although any upward or downward trends were difficult to ascertain, as were geographic trends. The cumulative sample aggregation method resulted in large fluctuations in quantile estimates. Furthermore, empirical confidence intervals for the extreme quantiles were very wide for much of the moving cumulative range, because of the inherently small sample sizes.

Climate indices were examined in the Midwest region by considering 60 years of daily rainfall data. One hundred and fifty rain gauge stations located in Illinois, Indiana, Missouri, Kentucky, and Ohio states were considered in this analysis. The daily rainfall measurements were obtained from the NOAA. Climate indices of maximum one-day precipitation, maximum five-day precipitation, number of days when recorded rainfall is more than 10 mm, number of days when recorded rainfall exceeds 20 mm, consecutive dry days, consecutive wet days, and very wet days were considered in this analysis. By dividing the time line to equal 30 years, the changes in the system were examined. The results of consecutive dry days and consecutive wet days were compared with the SPI index to understand the hydrologic droughts.

In this study, the precipitation was dynamically downscaled from two GCM outputs (CCSM3 and ECHAM5) to a finer grid scale (9 km) at hourly intervals and then was spatially evaluated against observations (PRISM precipitation) over the Northern California region. Six precipitation projections (A1B1, A2, B1, A1FI, Ensemble1, and Ensemble2) were used for this study. In general, the case of Ensemble2 shows the most realistic precipitation simulations against PRISM precipitation based on the comparisons of recent 11-year average precipitation fields. However, it is important to note that the case of A1FI also shows realistic trends in mountainous watersheds. This means that precipitation under the A1FI scenario is also important for future climate change impact studies.

Recently, few Lake Michigan watersheds in Northwest Indiana are showing increased trends in high flows. This study examines the influence of different factors over high flows. Low- and high-flow regimes can affect the watershed ecosystem and its sustainability, as well as flooding issues and flood mitigation. For planning purposes, it is important to understand and segregate the influence of land use changes and climate variables such as precipitation and temperature. This research work examines the data quantitatively and qualitatively in the high-flow regime of the northwest Indiana region. Further, the research investigates the use of an artificial neural network model (ANN) in identifying the influences of climate parameters and land-use changes over the high-flow regime. This research includes three watersheds in the northwest Indiana region: Hart Ditch, Little Calumet East Arm, and Deep River. High-flow trends in these watersheds were examined initially using qualitative and quantitative analyses using the Mann Kendall Test. Using 15 years of land-use data, monthly rainfall, and mean monthly temperature data, artificial neural network models were trained to predict the number of high-flow days having flow more than 15% probability of exceedance. An index, called relative strength effect, was calculated for each input after the successful training of the ANN model. This index, which is defined as the rate of change of output to that of a considered input, indicates the influence of each input. Based on this index, the effect of different land use categories, temperature, and precipitation over high-flow events was computed and documented. For the high-flow regime, this study indicates almost equal influence of climate variables and the land-use factors.

There is significant evidence that altering river flows downstream of reservoirs harms native aquatic ecosystems and decreases the ability of native species to strive and survive. Additionally, climate change has been shown to affect streamflow in regions throughout the world and threatens the same in the northeast. The Connecticut River is the largest river basin in New England, draining over 11,000 square miles and encompassing various land types including mountains, lakes, lowlands, and urban areas. As one of the most impounded rivers in the United States, the basin is highly developed in areas with a number of large dams for hydropower, flood control, water supply, and recreation located on the Connecticut mainstem and its tributaries. Innovative, climate-informed water management is needed to improve the health of native aquatic species and their surrounding ecosystems while maintaining the benefits from historic operating policies at these facilities. This research uses the Connecticut River Variable Infiltration Capacity (CRVIC) hydrologic simulation model to generate climate-impacted streamflows from downscaled GCM meteorological output. The climate-impacted streamflows are used as inflows into a large LINGO optimization model of reservoir operations in the Connecticut River Basin. A total of 54 reservoirs of varying purposes are modeled to examine the impacts of climate change on hydropower production, flood control, water supply, recreation metrics, and ecological targets. Impacts of climate change on low-head hydropower production are examined closely as the majority of hydropower dams within the basin fall into this category. A comparison is drawn between the baseline and climate-impacted operations for the reservoirs within the system. The use of optimization models in reservoir operations is explored with the goal of addressing objectives related to emerging environmental concerns in the hydrologic regime with the consideration of historical operating objectives for management of hydropower reservoirs in the Connecticut River.

Statistical downscaling modeling-based results often depict biases and are incapable of reproducing the variances and approximating the distributions of the predictands. This paper proposes a multi-objective optimization framework to reduce biases resulting from the limitations of the transfer function methods adopted under statistical downscaling procedures. The proposed formulations use a combination of several error measures including Linear Error in Probability Space (LEPS) to reduce any systematic biases. Also, different optimization algorithms both linear and nonlinear are evaluated for this purpose. The optimization formulations are applied and tested at 18 different locations for Support Vector Machine (SVM)-based statistical downscaling model results obtained from CGCM3 simulations for precipitation. Results indicate that the multi-objective optimization framework helps in reducing the biases of the statistically downscaled model results.

A 72-hour precipitation in a storm event over the American River Watershed (ARW) in California is maximized using a physically-based numerical model for a regional atmosphere. A storm event over ARW is caused by a high-moisture atmosphere coming from the Pacific Ocean, called "atmospheric river." Moreover, the path of an atmospheric river affects the amount of precipitation over the ARW. Therefore, the contribution of an atmospheric river to 72-hour precipitation over ARW is maximized by spatially shifting the atmospheric conditions for the numerical atmospheric model. In this study, this methodology is applied to the 1997 January storm event, one of the severest storm events over the ARW. Consequently, the 72-hour precipitation is maximized by shifting the atmospheric conditions southward by 6.0 degrees and westward by 1.0 degree, and the maximized value results in 568 mm. The results show that a historical storm event had the capability to cause higher precipitation, and the presented methodology is effective for the estimation of maximum precipitation over the ARW.

This study assesses the impacts of projected climate changes on reservoir sedimentation. Much attention has been paid to the impact of climate change on water supply (e.g., timing and magnitude of flows); however, little is known about the effects of climate change on reservoir sedimentation. Elephant Butte Reservoir on the Rio Grande in New Mexico was selected for this purpose. To predict the effects of climate change on reservoir sedimentation, several steps are involved. First, all of the 112 downscaled climate projections were divided into five categories, which provide average and extreme scenarios for reservoir sediment management and water operations. Second, hydrologic responses were simulated using the Variable Infiltration Capacity (VIC) hydrologic model to obtain the unimpaired flows at various gauging stations, which are then used to calculate regulated flows into the reservoir with the Upper Rio Grande Water Operations Model (URGWOM). Third, the total sediment load into the reservoir was calculated using the Bureau of Reclamation Automated Modified Einstein Procedure (BORAMEP), based on each sample's hydraulic properties, measured suspended load, and bed material gradation. Finally, sediment loads under the historical and climate change scenarios were calculated based on the adjusted rating curves.

Standard practice for designing hydraulic structures generally assumes that extreme events are stationary. However, it has been shown that in some cases hydrologic records exhibit some nonstationarity features, such as trends and shifts. Human intervention in river basins, the effect of low frequency climatic variability, and climate change due to increased greenhouse gases in the atmosphere have been suggested to be the leading causes of changes in the hydrologic cycle of river basins, which may also influence changes in the magnitude and frequency of extreme floods and sea levels that have been observed in certain parts of the globe. Various approaches have been used to analyze nonstationarity in hydrologic extremes, for example by application of frequency analysis where the parameters of a model vary with time. Basic methods used in designing flood-related hydraulic structures, such as return period (T) and risk (R), assuming a stationary world, can be extended into a nonstationary framework using the geometric distribution and changing exceedance probabilities over time. Building on previous developments suggested in literature, we present a simple and unified framework for estimating T and R for nonstationary hydrologic events along with an illustrative example.

We have proposed a new methodology to reduce uncertainties in regional climate hindcasts and projections. The fundamental premise of this work is observed regional climate trends, i.e., temperature trend is a combination of two major components: (1) natural climate variability signal and (2) global climate change signal in the region concerned. The new methodology combines regional natural (low frequency) climate variability with the global change signal from Coupled Model Inter-comparison projects phase 5 (CMIP5) climate models. While most parts of the world have shown a warming trend during the 20th century, the eastern United States has shown a cooling trend or lack of warming trend particularly after the 1930s. Using this anomalous temperature trends' example, we have first identified the relevant natural climate variability signal. We found that the North Atlantic-Multi-decadal oscillation (AMO) explains approximately 80% variance in observed trend variability in the Eastern United States. We employed AMO as natural climate variability signal and CMIP5 median trend as global climate change signal in the study. We found the proposed methodology provides a better model than all individual CMIP5 models, and the natural climate variability only model for the 20th century temperature trends hindcasts in the Eastern United States. For 21st century projections, we developed a statistical model for AMO variability (65-to-70 year oscillation cycle) using the past 155 years of observations. We relied on the AMO statistical model because (1) CMIP5 models have limited AMO simulation skill, and (2) it is rather difficult to extract AMO signal from CMIP5 simulations. We combined AMO simulations with the CMIP5 median trend for the 21st century temperature trends projections in the Eastern United States. The proposed new methodology shows significant potential in reducing uncertainties in the Eastern United States temperature trends' projections.

Geophysical processes could be self-similar under certain similarity transformations at certain time and space dimensions. In this study, the conditions under which the Saint Venant equations system for unsteady open channel flow through rectangular channels of varying width becomes self-similar under various time and space scales are investigated by utilizing one-parameter Lie group of point-scaling transformations.

The present paper highlights a combined research project among three universities, Universiti Sains Malaysia (USM), Universiti Teknologi MARA (UiTM), and Universiti Tenaga Nasional (UNITEN), in dealing with the water quality aspect of water security in Malaysia. Five subprojects were created to enhance the sustainability issue of water demand and supply. It is expected that the project as a whole will innovate new approaches and issues in urban water management in Malaysia.

The selection of a future energy source for Fairbanks, Alaska, is a multi-criteria, multi-decision maker (MCMDM) problem as it involves a range of stakeholders who must consider economic, sociopolitical, and environmental criteria in deciding the best project. The primary motivation for the new energy project is to provide an additional affordable heating and electric source to local residents. Proposed projects range from liquid-natural gas pipelines to hydropower and differ greatly in development costs, environmental impacts, and political support. Stakeholder interests vary from local and state government officials, to local and international business developers, and to residents and environmentalists. Traditionally, water and resource MCMDM problems have been simplified to analyze a single decision maker (DM) for multiple criteria; this work defines model criteria at different levels based on input from stakeholder representatives through a collaborative process. Model inputs can be ordinal when cardinal information is unavailable, thereby increasing the model's flexibility for a wide range of source data. The model employs a range of social choice, fall back bargaining, and MCDM to solve the problem. Uncertainty in the model is characterized by a Monte Carlo analysis, which measures sensitivity of the solution from the range of inputs provided by stakeholder data. Given the economic and social components included in this MCMDM analysis, characterizing the uncertainty associated with each outcome is crucial for policy interpretation. This work provides a new application for MCMDM problems combining a range of social choice and game theoretic methods with a rigorous sensitivity analysis to inform decision makers about the most feasible and stable alternatives.

The design of software for hydro operations and planning will affect many people within the hydro business enterprise, from duty schedulers to executives. The needs of these people have a common thread - the effectiveness of decision making in achieving the goals of the enterprise. It is a fundamental truth that this requires "decision support" software that serves the needs of the enterprise, especially the operators, not the goals of the programmers. So the starting point for software design is to find out exactly what is needed, the options that are available to explore, and how they must be presented in suggesting decisions.

Operation of reservoir systems represents a sequential stochastic decision problem. Stochastic dynamic programming (SDP) is a natural formulation of the problem for developing optimal decision rules, or the information needed to make optimal decisions. Pete Loucks was a pioneer in this area (Loucks 1968, Gablinger and Loucks 1970, and Loucks and Falkson 1970). The curse of dimensionality plagues dynamic programming models. Early efforts used composite representations of hydropower systems. More recent efforts use higher order approximations of the future value function and better use of hydrologic information. A better description of the joint distribution of flows and forecasts is provided by Sampling SDP (Kelman, et al. 1990; Faber and Stedinger 2001; Kim, et al. 2007; Eu, et al. 2011; Côté, et al. 2011). Ongoing work is described that uses Sampling SDP with a state-space corridor approximation of the future value function and radial-basis-functions for interpolation among nonequally spaced points.

This paper discusses the main benefits, feasibility, and challenges of implementing environmental flows in the lower reach of São Francisco River (SFR), Brazil, in the context of river basin revitalization, based on the experiences of a developed research project. The 631,133 km2 N basin of SFR covers 7.4% of the Brazilian territory, with enormous differences in its climatic and bio-physical characteristics. Rainfall ranges from 350 to 1,900mm over its area in normal years, the mean annual "natural" flow should be 2,850 m3/s, and flows at the mouth of SFR used to be greater than or equal to 854 m3/s in 95% of the time. SRF has been fragmented by dams planned to generate electricity mostly and also for flood control, irrigation, and water supply. Although some undeniable benefits exist, considerable environmental degradation and ecological losses have resulted from damming and water abstraction. The hydrological dynamics in its lower reach were extremely altered. Artificial dikes and river embankments prevent river-floodplain interactions, resulting in significant consequences on organic matter and nutrient fluxes and reproduction of the aquatic fauna as well. Navigation is now particularly restricted. Formation and immobilization of sandbanks have been noticed. The sediment budget at its mouth is now totally unbalanced, transforming the river-ocean relationship. Traditional fishery activities have been limited by stock depletion, resulting in impoverishment of local populations with consequent social ruptures. Even after all this, inter-basin diversion works are under way to export additional flows. The SFR Basin Management Plan refers to the benefits of "artificial flooding" in its lower reach, this way expecting to recuperate some ecological functions and to improve fishery. This exposes the need of implementing "environmental flows," what still may sound as an "unnecessary luxury" to some people, because land and water use conflicts and lack of access to water still remain. However, "environmental flows" must be addressed as a vital approach, given the imperative need of pursuing sustainability in the use of natural resources, indeed resolving those mentioned problems. A multidisciplinary research team dealt with the challenge of analyzing and proposing first steps for an eco-hydrological approach for SFR. First understandings about the possibilities of prescribing environmental flows for the lower reach of SFR were delineated. However, enormous obstacles still have to be faced: (a) prescription of more ecologically based environmental flows; (b) technical issues related to hydraulic structures of the dams; (c) the strong and unbalanced influence of the hydropower sector over other stakeholders; (d) political issues concerned to water managers, including problem understanding; (e) difficulties for agreement on trade-offs and compromises among stakeholders; (f) and uncertainties about water availability to meet the requirements of environmental flows due to current and potential water uses, besides the perspectives related to climate change.

The Mekong/Lancang River Basin is undergoing a period of rapid hydropower development. Construction of more than 20 dams is currently underway just in the lower Mekong Basin, with at least an additional 42 dams planned for construction in the next 20 years. The resulting alteration of the basin's natural flow and sediment regimes, geomorphologic makeup, and fish migration patterns could significantly affect the exceptional biodiversity and food production characteristics of the basin's ecosystems. This study is devoted to assessing the improvement in sediment passage (compared with current and expected conditions) that could be achieved at various locations in the basin by implementing reservoir sediment management practices such as sediment bypasses, drawdown flushing, seasonal drawdown routing, and sluicing. Specific sediment management options are discussed for selected reservoirs in the Sre Pok, Se San, and Se Kong sub-basins (called the "3S" basins). These sub-basins are particularly important with respect to biodiversity and ecological productivity and serve as an important source of flow, sediment and nutrients to the mainstream Mekong River. Simulations are performed with the Sediment Simulation Screening (3S) Model. Using a daily time step, this model simulates the mass-balance of flow and sediment to predict in relative terms the spatial and temporal accumulation and depletion of sediment in river reaches and in reservoirs under different sediment management policies. It also identifies the relative tradeoffs between hydropower output and reliability and sediment regime alteration for these sediment management options.

SIGA (Information System for Water Management and Allocation) is a generalized water resources system developed to help the planning and operation of water resources systems. Based on a node-link water resource network, SIGA has simulation, optimization, hydrologic, and water quality models to simulate the impacts of management and allocation rules in a water resources system. This paper presents the formulation and components of SIGA and its application to water allocation in the Upper Jaguaribe river basin, in the Ceara state of Brazil. The water allocation in Ceara is based on a negotiable process that relies on technical information (reservoir storages, water demand, and availability scenarios) and participatory involvement of stakeholders. This paper presents the scenarios built in SIGA using two different methods of water system simulation showing possible improvements on the decisions by revealing the risks related to each allocation alternative.

To address severe water stress in the Zayandeh-Rud River Basin in central Iran, a number of inter-basin water transfer projects have been implemented that have more than doubled the natural flow of the river. This study aims to evaluate the reliability of inter-basin water transfer as a long-term solution to meet the growing water demand in this basin. A system dynamics model is developed to capture the interrelationships between different sub-systems of the river basin, namely the hydrologic, socioeconomic, and agricultural sub-systems. Results indicate that supplying more water will lead to watershed development and consequently increased water demand, when the interrelated dynamics of the problems are ignored. It is demonstrated that the "fixes that backfire" archetype dominates the Zayandeh-Rud River Basin management system. This archetype hypothesizes that the water shortage problem will diminish by water transfer projects, for a short while and then more severe water stress returns to the basin in the long run. Therefore, inter-basin water transfer alone is an inadequate water management solution, with a potential to cause significant unintended consequences and secondary negative effects over time.

ASCE Policy Statement 465, Academic Prerequisites for Licensure and Professional Practice, seeks to advance the educational requirements for licensure as a professional engineer and would require 30 upper division or graduate level credits beyond the bachelor's degree. The policy specifically alludes to the need for further specialization in the statement "These changes1 have created a need for civil engineers to have simultaneously greater breadth of capability and specialized technical competence than that required of previous generations." At the same time several opportunities for specialty certification in civil engineering and more specifically water resources and environmental engineering are now available and the linkages between advanced education and admission to such academies are readily apparent.

After teaching hydrology classes for 40 years, the first author requested students access the following websites and complete the exercises useful in hydrology applications: 1. (http://www.noaa.nws.gov) Access National Weather Service rainfall data for gauges in city or region (such as the Houston/Galveston region). 2. (http://www.harriscountyfws.org) Access flood warning system, plot rainfall total for county (Harris County). For heavy rainfall totals, draw 15.0, 10.0, 5.0 rainfall contours/isohyets or smaller increments for lesser rains. Also see:http://www.hcoem.gov 3. (http://www.waterdata.usgs.gov) Access U.S. Geological Survey Water Resources Data for streamflow for a local basin (such as the San Jacinto River). 4. Selected Texas flood videos are available from the Texas Natural Resources Information System: goo.gl/maps/qE9w meta data. Texas historical high water marks updated monthly are useful hydrologic data readily available through google.com/fusiontables/DataSource?d ocid=1gT3F42twZSi5TCc2Q5GSF0enntCC2rPW404n-J4. 5. (http://www.hec.usace.army.mil) Download HEC- HMS computer program and complete homework assignment: HEC-HMS modeling problems 5-3 to 5-6 from Bedient, Huber and Vieux, Hydrology and Floodplain Analysis, Prentice-Hall, 2008, 2013. 6. (http://www.noaa.nhc.gov) Download national hurricane center data for plotting Caribbean/ Gulf of Mexico. Daily: plot hurricane coordinates until 24 hours from U.S. landfall, forecast landfall location. Compare actual hurricane path (as Hurricane Issac). 7. To apply reservoir routing techniques such as the Modified Puls or Storage Indication methods, flood streamflows and reservoir storage elevation-discharge data or curves need to be available or compiled and utilized for a reservoir case such as Lake Houston. The second author has worked for a state water and information service agency and uses hydrology websites regularly. An exercise is presented that allows students to compare what actually happened vs. results of theoretical rainfall and regulation models. Students (learning to access the websites for regional, state, and federal rainfall and streamflow) can compile storm information reports (for jobs or research). A survey on accessing hydrologic websites from selected past students in the workforce will be compiled and presented.

Water supply for Shimla, a popular hill station in the northern part of India, was initially planned and executed by the Britishers in the year 1875 for a meager population of 16,000. Over the years, the city has grown both geographically and demographically, and water demand increased manyfold. From 1875 to date, the Shimla water supply system has expanded into seven independent water supply schemes originating from Dhalli Catchment, Cherot Nallah, Chair Nallah, Nauti Khad-I, Ashwani Khad, Nauti khad-II, and Giri River. Total water demand (2012) is 64.66 million liters per day (MLD) against source supply of 54.54 MLD. The gap between demand and supply further increases with system inefficiencies, as a result there are consumers who are getting water supply only for about 45 minutes in a day. The present deficit of 10.12 MLD (2012) will further amplify to 21.27 MLD in 2021and 42.61 MLD in 2031. Domestic water demand (2012) is 35.17 MLD (12.84 billion liters per annum) whereas if 30% of the rainfall is harvested in built-up areas (1475.76 hectares), 19.12 MLD (6.98 billion liters) of rainfall can be harvested annually, equivalent to 54% of domestic water demand. The capacity of six existingsewage treatment plants is 35.63 MLD, and effluent can partly be reused after treatment for nonpotable consumption. To fulfill the growing water demand of Shimla, the available options are (i) gravitating water from upper reach of River Pabbar, (ii) lifting water from River Satluj, and (iii) rainwater harvesting and reuse of waste water coupled with balance additional water from River Satluj or Pabbar. In this study issues and challenges of water supply in Shimla, reasons for water deficit, and in-depth analysis of future demand and supply are discussed. Further, feasible augmentation strategies, role of rainwater harvesting, and reuse of waste water for mitigating the water scarcity have been critically examined for the sustainable water supply to Shimla city.

The Rio Ojo de Agua Flood Control Project was authorized to reduce flood damages to the historic municipal area of Aguadilla in Puerto Rico. Storms frequently impact the city of Aguadilla with significant flooding and sediment loads, which include large rocks and debris. The impacted area is highly urbanized with several significant historical sites that were preserved. The project has a concrete crib dam that was constructed at the upstream portion of the project to reduce the amount of debris and rock that flows into the city. The downstream portion was constructed with a high-velocity channel and culvert for supercritical flow that was cut relatively deep into a Karst formation, which contained an artesian well that was extremely close the newly constructed channel. That well is pristine with a major historical significance to the Commonwealth of Puerto Rico and the City of Aguadilla. This paper will describe the successful design and construction of the project features. It will also focus on the method of construction and the required onsite monitoring techniques that were performed to preserve the historic sites including the well during the construction of the project. This paper will spotlight the water resource engineering aspects of the project, such as how the construction features were built in a flash flood environment and how the project preserved the maintenance of flow through the project area. Other key technical water resource engineering aspects of the project such as the installation of gauges and on-site monitoring and testing to prevent any groundwater impacts during the construction and post-construction phases to the historical well will be demonstrated.

In this research, membrane vibration was examined as a new way to control the phenomena of concentration polarization (CP) in forward osmosis (FO) processes. A batch reactor was developed for dynamic studies on FO's flux behavior. The performance of "fresh water" production and reverse diffusion in the FO process were evaluated by vibrating the FO membrane under different experimental conditions. Results indicate that, with a NaCl solution (concentration = 1.0M) as the draw solution, the flux was 20-50 L/m2-h for the membrane vibration, which is much higher than that generated by the magnetic stirring method (1-6 L/m2-h). The energy consumption of the method was relatively high, but was lower than that of a RO process. It is concluded that membrane vibration could increase the flux of fresh water production and thus may be used to control the CP better than the methods being used currently.

In the present study, GPS, GIS, and remote sensing techniques were employed for identifying the suitable locations to set up micro hydropower stations on the major distributory (D-83) of Kakatiya main canal on Godavari river, Andhra Pradesh, India. The study deals with evolving the geomatic approach to identify suitable locations. Canal plan and profile have been identified by using toposheets and contours of canal area with one kilometer buffer on both sides are generated in GIS environment. Identification of suitable locations for setting up hydropower stations is done by integrating multisource datasets in GIS platform. Twenty-six locations of suitable sites along the total length of the D-83 canal are identified as suitable to set up small power plants. Heads of 1.219 m, 1.829 m, 2.438 m, 3.048 m, and 3.657 m along the total length of the D-83 canal have been identified as suitable to set up small power plants.

A WDN capable of sustaining failure of any one pipe without causing disruption in services either in full or part is considered as the level-1 redundant network. Unknown future water demands are treated as fuzzy parameters using fuzzy logic technique. Fuzzy optimization model is formulated for design of level 1 redundant WDN considering fuzzy demands. Fuzzy nodal demands are characterized by triangular membership functions. For each node, membership function for the available nodal heads is also considered to be approximately represented by triangular membership function. Furthermore, desirable nodal heads are also considered fuzzy. Relationship between fuzzy available nodal heads and fuzzy desirable nodal heads is used to convert fuzzy constraints to crisp constraints. Genetic algorithm that can easily consider multiple demand scenarios for various pipe failure conditions is used for determining the optimal design cost. The proposed methodology has been illustrated with an example network.

The proliferation of wireless sensors in everyday consumer products presents new opportunities to monitor the environment at unprecedented space and time scales. This study explores the utility of pervasive sensors for improving the resolution of areal precipitation estimates through fusion with weather radar observations. While these sensors are not specifically designed to measure rainfall intensities, the data they collect can be repurposed to provide quantitative measurements of environmental variables at the location of the sensor. Due to different measurement accuracies (which may be time dependent), types of spatial and/or temporal measurement support, and measurement frequencies of the component sensors, it is unclear how best to combine measurements from pervasive sensors with those from traditional sensors. The method developed in this study employs Markov random field models to compute the likelihood of rainfall at sub-grid pixels. These likelihoods are used to "unmix" the block-averaged rainfall rate measured by the radar. The statistical nature of the model permits the data evidence to drive the fusion of the sensors' measurements. The performance of these methods will be illustrated using case studies exploring synthetic and real-world data.

Climate change has highly affected the natural water system as well as the ocean-atmosphere relationship over the world. Recent investigations show that increasing sea levels in different regions is a result of climate-change impacts. Sea-level rise increases the risk of coastal floods. Coastal areas are projected to be more frequently flooded every year resulting in significant economic losses. Partially, it is attributed to monthly variations due to tidal effect or gradual increase in sea level rise due to climate change. Therefore, in management of coastal areas, the projection of changes in sea level is important. This paper aims to provide a scheme for simulation of gradual increase in the sea level in New York City. Based on the recent studies, a significant relationship exists between sea level changes and climatic variables such as sea-level temperature and pressure. Therefore these variables are used for sea-level simulation through a statistical model. Regarding the large number of climatic variables in different points that can affect the sea-level changes in New York City, factor analysis is used to determine the most effective variables in sea-level change predictions and combine them into new variables to be used in sea-level prediction relationship. The projected climatic variables by General Circulation Models (GCMs) under climate change scenarios are used for realization of future sea-level changes.

Pressure surge, also known as water hammer or hydraulic transient, is a time-varying momentary phenomenon. It happens when the equilibrium of a flow system is disturbed by a status change over a relatively short time period. Caused by either immediate startup or shut-down of pumps, or rapid opening or closing of valves, surge events can introduce large pressure forces and rapid fluid accelerations into a water distribution system, which may result in pump and device failures, system fatigue or pipe ruptures, and even dirty water backflow/intrusion. Therefore, surge protections are extremely important for the design of hydraulic systems. This paper reviews the commonly used surge control strategies that include redesign of the plan and profile of the pumping station and pipeline system; selection of pipes and fittings to withstand the anticipated pressures; identification of proper start-up, operation, and shut-down procedures for the system; and selection and location of the proper control devices to mitigate the adverse effects of surge events. The pros and cons of the control devices, such as hydropneumatic tanks, air valves, surge valves, and pump control valves, are also discussed. A pump station and its transmission/distribution system in Somerset, Texas, is proposed to provide drinking water from the to-be-upgraded Somerset pump station to its serving areas including three different pressure zones: 830, 730, and 790. This project is a part of the San Antonio Water System's (SAWS) district special projects and upgrades to the facility are necessary to support integration of the pump station into the SAWS network. This system includes, but is not limited to, the Somerset pump station and the water distribution network including ground and elevated storage tanks. The system has a design capacity of 5.441 million gallons per day (MGD) representing the maximum hourly demand of the system. Without surge protections, the surge analysis results indicate that the pump and distribution system can have serious downsurge (low negative surge pressure) problems. The goal of the surge analysis is to provide a cost-effective surge protection system to mitigate the potential surge damages. Specifically, downsurge pressures need to be checked and reduced to the minimum impact. Based on the surge modeling results, hydropneumatic tanks and other devices and strategies are proposed to mitigate the downsurge impact. The final simulation results indicate that the surge control strategies will provide reliable surge protections to the pumping and pipe systems.

Local governments and utilities across the nation are starting to address the needs for implementing more sustainable stormwater and watershed management strategies. These needs are driven by the necessity to reduce stormwater contributions to combined sewer overflows (CSO), water quality and designated use issues, total maximum daily load (TMDL) requirements, numeric nutrient criteria, and flood risk reductions. The U.S. Environmental Protection Agency (USEPA) has recognized the value of more "green" stormwater management approaches and has encouraged CSO programs, municipal separate storm sewer system (MS4) National Pollutant Discharge Elimination System (NPDES) permittees, and wastewater NPDES permittees to more actively implement sustainable programs including green infrastructure (GI) and low impact development (LID). Many stormwater management engineers have been skeptical of the real benefits of GI and LID for stormwater management compared with traditional best management practices. However, stormwater programs including GI and LID have been successful in communities across the country, showing that sustainable solutions have a place in the stormwater management toolbox. The Municipal Sewer District of Greater Cincinnati (MSDGC) is leading a major program that is taking a holistic approach to stormwater management as part of its overall CSO management strategy. Project Groundwork, MSDGC's wet weather implementation program, is focused on meeting federal mandates for CSO and sanitary sewer overflow (SSO) management as well as on improving overall water quality and public health. Simultaneously, the program has been designed to consider enhanced social, economic, and environmental outcomes of implementing a combination of green and traditional grey stormwater and CSO management alternatives. Watershed planning efforts have been guided by a sustainable watershed evaluation process to help identify the most affordable, socially responsible, and environmentally effective plans for each watershed in the MSDGC service area. This process, the Sustainable Watershed Evaluation and Planning Process (SWEPP), has been revised and enhanced to provide guidance for future watershed planning efforts to ensure that sustainable strategies are efficiently developed and evaluated. In the Upper South Branch Mill Creek watershed, the SWEPP is being applied to identify alternatives for meeting CSO and SSO issues in this highly urbanized watershed. Sustainability of the suite of green and grey alternatives is being evaluated using a combination of water quantity and quality modeling, business case evaluations (BCEs), and web-based tools. Community involvement and interagency collaboration have been incorporated throughout the process to ensure local community needs and goals are addressed in the evaluation.

This research is motivated by the need to develop low cost, wireless, environmental sensor networks for monitoring hydraulic and water quality variables in streams and watersheds. Salamander is the Serial Amphibious Linear Arrays of Micro and Nano Devices for Environmental Research, and the tool provides a versatile instrumentation platform for deploying hydraulics and water quality sensors within stream networks. The Salamander is designed to collect and transmit a variety of hydraulics and water quality data using inexpensive sensors and wireless technologies. We outfit Salamander for estimating sediment flux at cross-sections in a stream using inexpensive velocity bend sensors, light attenuation sediment sensors, and temperature and pressure sensors. The field site chosen for testing the sensor network is at the confluence of 1st, 2nd, and 3rd streams to gain a better understanding of the effect of spatial scales on sediment transport within the watershed. Downstream of the confluences the hydrograph and sedigraph are approximately the linear addition of the upstream tributaries. Wireless data transmission from the Salamanders to the data storage location was successful, and ongoing research is underway to model the data within the cyberinfrastructure created by the Virtual Observatory and Ecological Information System. The results of this work show that the inexpensive Salamander network can be quickly deployed in the field to monitor hydrologic events of interest to the researcher. Intelligent features are currently being designed and implemented to approximate the velocity and sediment distribution and thereafter compute sediment flux for the cross-section while performing calculations on parameter gradients to check for erroneous data.

The developing world is littered with failed projects. There are countless examples where overly sophisticated equipment has been introduced into developing communities only to break down and sit idle because the communities were not educated in operation and maintenance and did not have the finances or materials for repairs, or simply because they did not understand the importance of "development." Despite the good intentions of well-meaning individuals, these projects have not been sustained and often cause more problems than they solve because project planners, engineers, social scientists, and the target communities frequently misunderstand or disrespect each other's perspectives. To try and take a more holistic approach to development, this case study reviews a community-based participatory approach that elicits emic perspectives through photography and participant interviews to try and determine the most pressing health needs of a small, peri-urban community in eastern Guatemala.

Yemen is ranked 154th out of 187 countries in the Human Development Index, a ranking that has generally held steady since 1990. The violence and political upheaval of the past year in Yemen have resulted in large-scale displacement of Yemeni people and deterioration of the Yemeni civil infrastructure. Yemen continues to grapple with the decline of its water resources. In terms of per capita water availability, Yemen is the most water-stressed country in the world and one of the 10 poorest in terms of all available resources. The typical paradigm for international aid tends to divide funds and efforts into three categories: relief, recovery, and development. The international community tends to respond to natural or political disasters with large sums of financial and material aid, which result in no meaningful reduction in vulnerability to the next (and often imminent) crisis. This paper suggests (based upon a case study of a World Food Program food-for-work initiative in Hajja and Hodeidah, Yemen) that investments of labor, materials, and funds in food or financial relief (emergency response) should be coupled with innovative and uncompromising commitment to improvements in Water, Sanitation, and Health (WASH)-related policies, practices (e.g., hand-washing, community-led total sanitation) and infrastructure (e.g., watershed improvements, cisterns, water filters, wells, rainwater harvesting systems, hillside terraces, latrines, toilets, etc.) that result directly in local ownership of greater food security, health, and control of water resources (including invulnerability to and resilience in the recovery from floods and droughts).

The Hope College Student Chapter of EWB-USA, in partnership with the Life and Water Development Group - Cameroon, recently completed a community scale water resources program with a rural farming community in Northwest Cameroon. The program included the following components: a gravity-based water distribution system consisting of a diversion dam, 10,000 L storage tank, 27 tap stands, and more than 9 km of conduction and distribution pipeline; household scale water filtration that included on-site construction of 180 concrete Manz biosand filters; and health/hygiene education for women's groups and other community stakeholders. This paper describes the organization, planning, and implementation of the system components while also examining some of the broader impacts related to community development within the host community. Emphasis is placed on the overall project timeline and the identification of appropriate technologies based on feedback from the community. The paper will also discuss challenges that were encountered in the early phases of the program due to a lack of participatory planning.

Engineers without Borders - USA has been implementing water supply projects in partnership with communities in developing nations for the last 10 years. During these 10 years the organization has grown from one project in one country to hundreds of active water supply projects in dozens of countries. The organization has used the lessons learned from these 10 years of projects to create principles that guide the way that we carry out the assessment, design, implementation, and monitoring of infrastructure projects in partner communities throughout the world. The principles are used by the organization to help identify communities that need and are able to accept the engineering assistance of EWB-USA. They help us work with the partner community to identify and assess the problem with their water supply and develop an engineering solution that can be constructed using locally available materials, labor, and equipment. Most important, they allow the organization to work with communities to develop solutions that can be sustained or maintained by the community using its own financial, technical, and manpower resources. EWB-USA has found that water supply project failures stem often not from specific technical design flaws, but rather from nonengineering issues related to the project. Therefore the EWB-USA development principles concern not only the engineering aspects of the water supply projects but also the essential nonengineering aspects of the projects. The development principles that are described in this paper relate to the EWB-USA relationship with the partner community, community education requirements for a water supply project, in-country partnerships, the appropriateness of technology for a given situation, and the sustainability of water supply projects. Though they were developed by EWB-USA, these principles are applicable for water supply development projects carried out by other organizations.

This paper describes a conceptual modular sustainable water supply (SWS). The system can be assembled at relatively low cost and shipped to remote locations, where it can be installed using mostly local labor in preexisting, or new groundwater wells. The system is powered by solar energy during the day and could be designed to accommodate a village of any size; the base case solution being presented here would be capable of supplying water to a population of 800 to 1,000 people. Furthermore, the system will store excess energy and will also produce additional energy during water consumption that can be used as additional power for a small but socially important electrical grid. The system incorporates a modular control unit that may include a UV water disinfection unit as needed. The introduction of a SWS system in an at-risk community would have several positive impacts. It would increase the water availability to the community with the consequent benefit of reducing the potential for disease and mortality, especially among children. It would provide electrical power for essential community needs, thus increasing the potential for educational activities. It would relieve the population from the need to collect and transport water and the wood or fuel necessary for cooking and other activities. Finally, it would require the participation of local labor, both at the production location and in the target community with the added benefit from training and skill development. Once in operation, the system should be able to be maintained by the community itself.

Construction of international sustainable engineering projects in developing communities by student organizations such as Engineers Without Borders involves a minimum of four basic stages: (1) project acquisition based on the communication of the need for the project; (2) travel to the project for site assessment; (3) project design, logistics, and communication of the design with the communities involved; and (4) travel to construct the project. In general, when construction projects are completed locally, there is an ease of communication and travel that shortens all four stages and inevitably the entire process. By comparison, distant locations, language and cultural differences, and exotic politics lengthen these processes, at times creating barriers that prevent the completion of much needed initiatives. An excellent counter to this situation is to utilize a native in-country coordinator who is privy to the local language and dialects and the cultural norms that stupefy outsiders and is available for site visits to assess progress and answer any design questions the foreign engineers may have. The in-country coordinator predicts the needs of the projects based on his or her background knowledge gained from being native to the area, thus preventing the engineering group from many misunderstandings and perhaps poor design constraints. The fundraising that is required to pay in-country coordinators to ease these processes poses a threat to the ability of student organizations to hire them; however, without their expertise and inherent ability to communicate easily with the community receiving the project, the completed construction and sustainability of the venture is put at risk.

The potable water system in Tingo Pucará serves an indigenous community of approximately 100 people living in the Ecuadorean Andes and is unique in both the daunting scale of its design and its extensive collaboration with in-country partners. As a result, the tri-chapter efforts of the Pittsburgh Professional, Carnegie Mellon University, and University of Pittsburgh Engineers Without Borders chapters that helped design the system were recognized with a 2012 EWB-USA Premier Project Award. At first, however, the sheer scope of building a single-stage pumping system powered by grid energy over 900 m of steep (< 37 ° slope), sandy mountain almost caused the project to be abandoned. Instead, the strong in-country support, including the nongovernmental organization HCJB, a local Peace Corps volunteer, funding from the local municipality and electrical utility, and prodigious effort from the community of Tingo Pucará, supported the project to completion. Construction was not the only part of implementation; the chapter also had to navigate cultural expectations, develop an appropriate price point for household customers, and foster a water board that could care for the system throughout its lifetime. With the installation of the water system, the EWB team aims to improve the community's quality of life by reducing time spent gathering water and decreasing incidence of waterborne illness. Finally, the community water board will provide project sustainability as the water system moves forward.

The white rot fungus Pleurotus ostreatus was analyzed as a potential biocontrol agent used to reduce the amount of coliform bacteria in simulated wastewater and storm water runoff. On water agar plates, Pleurotus ostreatus was seen to prey on bacterial colonies and completely consume them within 72 hours. Based on this principle, biocell reactors (BCR) were used to determine the effectiveness of spent mushroom compost (SMC) containing P. ostreatus to reduce the concentration of E.coli in simulated wastewater and stormwater runoff. After the first 12 hours, the overall concentrations in the live reactors began to decrease while the concentration in the dead control began to increase. After a subsequent uncontaminated rain event, the E.coli concentration in the dead controls increased exponentially while the overall concentrations in the live reactors decreased. The simulated wastewater effluent treatments, while having the lowest total concentration of E.coli, did not decrease over time. This suggests that the presence of the live fungus kills the adsorbed E.coli and that nutrient concentrations may play a significant role in the level of predation observed.

Aqua Clara International (ACI) is a nonprofit organization that uses biological sand filters (BSFs) to provide economical, clean water to families in developing countries. ACI often recommends loading 20 L/d in BSFs in which a brass alloy is included as a disinfectant. A bench-scale study was conducted to investigate the effectiveness of using copper as the disinfectant. Five filters were constructed to compare different arrangements and amounts of copper shavings to a control, column 1. The control was modeled after ACI design specifications but no metallic disinfectant was included. Columns 2 - 5 were also scaled according to ACI recommendations. Columns 2 and 3 each contained 4.7 g of copper, and Columns 4 and 5 each contained 2.35 g. In columns 2 and 4, copper was placed in a single layer; while in columns 3 and 5, the copper was dispersed throughout the fine sand. After 31 days of testing, the average removal efficiency for total coliforms in columns 1 - 5 was 96.5%, 93.9%, 97.4%, 95.4%, and 97.5% respectively. A single, 20 L/d BSF was constructed with 94 g of copper dispersed throughout the fine sand layer. The average removal efficiency for fecal coliforms and turbidity was 97.3% and 65.7%, respectively.

We aimed to determine the scale of stressor impacts on phytoplankton in the Laurentian Great Lakes. Algal abundance of 72 pelagic locations was summarized for the seven main phytoplankton classes. The nearest shorepoint to each pelagic location was used to generate reaches of various lengths. Watersheds intersecting each reach were quantified for the six stressors: agriculture, urban area, population, point sources, roads, and a composite stressor. Phytoplankton data were modeled with the stressors using regressions at the various shoreline reach sizes. Model fits were compared among phytoplankton classes, indicators, stressors, shoreline sizes, and seasons. Cryptophytes and diatoms had the strongest relationships to stress; cell density had a stronger model fit than biovolume; agriculture and population were the most important determinants of phytoplankton abundance; phytoplankton were better related to stress quantified from larger reaches; and spring assemblages were more strongly associated with stress than summer assemblages.

This paper presents data from three years of monitoring of Mecoprop on landfill sites and potential rivers and streams in North West England from the clean headwaters to polluted rivers just above the tidal reach and covers six landfill sites including their potential receptors where the runoff drains. Across the basins that include areas of rural, urban, and industrial typologies, data is presented for one of the priority substances in the Water Framework Directive, i.e., Mecoprop. Average concentrations are low and well below the drinking water Quality Standards values for Mecoprop with occasional concentration above the DWS in groundwater and surface water, ranging between 0.005 μgl-1 to 7.96 μgl-1. Mecoprop appears in concentrations in the leachate quality for landfill sites studied, values ranging between 0.06 μgl-1 to 3560- μgl-1 in cells. High concentration of Mecoprop in the leachate quality suggests that there is a possible source term from the waste deposited on sites. Migration of Mecoprop is simulated using the Landsim (Landfill Performance Simulation) modelling program to predict Mecoprop concentration in groundwater and potential aquifer. Mecoprop were found to exceed the European Union and US-EPA drinking water standards at the unsaturated zone /aquifer. The findings demonstrate the pollution potential arising from Mecoprop presented in leachate quality from landfill site, a nonagricultural source point.

The Brazilian hydrothermal system consists of a completely linked network of 143 medium and large hydropower plants, 888 small hydropower plants, and 1,602 thermal and 82 wind power plants, with a total installed capacity of 128,570 MW. The hydropower plants produce, on average, 91% of the total electricity consumed in the country, while the complementary thermal system is dispatched mainly during periods of drought. In our previous studies, we developed a nonlinear programming model, HIDROTERM, to optimize the management and operation of the hydrothermal system, considering individual hydropower plants, thermal generation and exchange, multiple uses of the water, and system expansion. The model is deterministic. In this paper, we develop a new version of HIDROTERM to incorporate the stochasticity of the inflows in the formulation. Additionally, hourly load variation is represented by three levels: peak, base, and low. The proposed approach is based on two-stage stochastic programming with recourse. In the first stage (first time period) the system passes from its initial state to the final state based on deterministic inflow forecasts. From the second time period on (the second stage), the state of the system branches out according to inflow scenarios. The branching can be scaled up gradually until the end of the planning horizon. New developments are made in the formulation, interface, database, and the underlying simulation model. The newly developed integrated decision support system is being tested on the entire Brazilian hydrothermal system.

This research evaluates the quality and value of forecasts generated from the Climate Forecast System version 2 (CFSv2) using the Jackson Hydropower Project on the Sultan River in Washington State as a case study. Streamflow reforecasts are generated and used to evaluate the predictive skill of the CFSv2 in the context of decision making and reservoir operations. An analog method is used to downscale and bias correct the CFSv2 reforecast data by selecting scenarios from the observed record that are similar to the current CFSv2 precipitation conditions. These constructed analog data serve as input to a watershed model (SAC-SMA) that generates streamflow values. Finally, the streamflows produced from the analog reforecast data, climatology, and the observed record are run through an optimization model of each system. Metrics of system performance are compared for the reforecast, climatology, and observed scenarios to evaluate the potential benefits of using CFSv2 seasonal forecasts in systems decision making.

Current water management practices are mostly targeted toward quantitative uses, while water quality is usually addressed separately as an independent problem. In this work, a novel reinforcement learning approach is proposed for designing Pareto-optimal operating policies for reservoirs equipped with selective withdrawal systems (SWSs). This approach exploits the feedback between the selection of outlet locations for water quantity demands and the water quality patterns within the reservoir, making it possible to satisfy downstream objectives and, simultaneously, affect in-reservoir water quality. Dealing with many water interests, a novel method is presented for reducing the number of objectives via Non-negative Sparse Principal Component Analysis (NSPCA). The approach is demonstrated on the real-world case study of Tono Dam (Japan). Results indicate that potential control over water quantity and quality can be gained by effectively exploiting SWS's flexibility, taking advantage of the NSPCA-based reduction of the operating objectives.

Stream flow records and irrigation delivery and return flows are typically estimated with the use of stage-discharge ratings. These ratings may be for channel control or for measurement structures. The conventional rating method relates stage to discharge; however, at sites prone to flow reversals, changes in stream bed roughness, backwater, or tidal effects, the relation between stage and discharge is not unique and a velocity-index rating is often developed. A velocity-index rating relates the mean velocity in the cross-section to an index-velocity determined from velocity measurements at defined locations in the cross-section. Application of velocity index ratings assumes that the relation between the measured index velocity and the mean velocity in a cross-section is constant. This assumption is not valid if the channel experiences significant flow disturbances. This paper presents a virtual flow meter developed to evaluate the effect of hydraulic factors such as vegetation growth, obstacles, variable backwater, etc. on the stability of velocity-index ratings for different instrument and measurement configurations. A three-dimensional computational fluid dynamics (CFD) model was used to simulate velocity distributions that would result from various flow and channel conditions modeled. The virtual flow meter allowed for different instrument configurations (i.e., number of acoustic beams, angle between beams, orientation of instrument, location of instrument, etc.) by specifying an instrument configuration and then sampling the simulated velocity field at locations based on the specified configuration. The index velocities sampled by the virtual flow meter and the mean velocity at the cross-section were used to develop velocity-index ratings and examine the effect of changing hydraulic factors on the uncertainty in the discharges determined from the rating. The analytical tool described in this paper provides insight to both the effect of changes in flow and channel conditions, as well as changes in instrument configuration, on velocity-index ratings.

In a water distribution system it is very important to study the influence of the variation of the rotation pump flow in piping systems with respect to forced flow and pressure, because the use of pumps is an increasingly common sanitation system. At the Federal University of Itajubá, UNIFEI, there is a reduced model system that mimics a water distribution system containing hydraulic elements such as pipes, suction pumps, valves, and reservoir supply. In this study we evaluated these parameters on a series of conditions of rotation. In this system there is one inverter frequency ranging from 1750 rpm to 3500 rpm rotation. The results were consistent with existing theories leading to hydraulic correlations.

The erosion rate of cohesive soils is typically computed using an excess shear stress model based on the applied fluvial shear stress. However, no mechanistic approaches are available for incorporating additional forces such as localized groundwater seepage forces into the excess shear stress model parameters. Seepage forces are known to be significant contributors to streambank erosion and failure. The objective of this research was to incorporate seepage forces into a mechanistic fundamental detachment rate model to improve predictions of the erosion rate of cohesive soils. The new detachment model, which is referred to as the "Modified Wilson Model," was based on two modified dimensional soil parameters (b0 and b1) that included seepage forces due to localized groundwater flow gradients. The proposed model provided a general framework for studying the impact of soil properties, fluid characteristics, and seepage forces on cohesive soil erodibility. The proposed model will be described and methods of analysis will be presented for deriving the material parameters from flume tests and jet erosion tests (JETs). To investigate the influence of seepage on erodibility, innovative submerged JETs and larger-scale flume experiments were conducted including cases with and without seepage. Seepage forces influenced the erodibility parameters (b0 and b1) and the corresponding predicted erosion rates. As expected, increased seepage gradients or forces decreased b1 and increased b0 for both flume tests and JETs. The influence of seepage on erosion can be predicted using the "Modified Wilson Model" parameters with a priori flume and/or JET experiments without seepage. Erodibility parameters with or without seepage from flume experiments were statistically equivalent to those derived using JETs. The "Modified Wilson Model" is advantageous in being a more mechanistic, fundamentally based erosion equation that can replace the more commonly used empirical detachment models such as the excess shear stress model.

A two-dimensional numerical model is developed to simulate turbulent shallow-water flow. The model is based on two-dimensional depth-averaged Navier-Stokes equations. A second-order Godunov-type upwind finite volume scheme with augmented HLLC Riemann solver is implemented. The conservative variables near the edges of cells are linearly reconstructed by the MUSCL scheme. The reconstructions are based on the primitive variables. The time marching scheme is a second-order TVD Runge-Kutta scheme, which can prevent the occurrence of oscillation in every intermediate stage. The model uses first-order approximations for the wet-dry fronts and boundaries, which make the solution as robust as possible. An additional flux is calculated to keep the scheme well balanced. To provide body-fitted mesh, the Cartesian cut-cell method is adopted. The κ - ɛ turbulence model is implemented as the turbulence model closure. The model is tested against several laboratory experiments and field measurements. In all test cases, the simulated results agree well with the observations.

The shallow water equations (SWE) are a popular choice in gravity current (GC) models because of the good balance between accuracy and computational effort. This work presents a two-layer SWE model developed for high Reynolds number GC that accounts for ambient crossflows often encountered in the environment. The mathematical model is written in conservative and divergent format to account for the possibility of naturally occurring discontinuities and is solved with the nonlinear HLL scheme using a finite-volume framework. The depth profile and front trajectory for a constant-volume release compare well to a similar model proposed by Hallworth et al. (1998). The proposed model is also tested with density intrusion experiments, and the front velocity results compare well for both coflow and counterflow currents.

When stormwater storage tunnels undergo rapid filling during intense rain events, many different mechanisms can lead to the entrapment of air pockets within these tunnels (Vasconcelos and Wright, 2006). Entrapped air pockets have been linked to operational issues like damaging surges, loss of storage capacity, and severe geysering upon release through water-filled ventilation shafts. Tracking of entrapped air pockets and their celerity is thus important in the context of numerical simulation to assess the risk of these operational issues. Previous studies focused on quantifying the magnitude of surges associated with air pocket compression or in obtaining the minimum flow velocities required to expel these entrapped pockets in water mains. However, the mechanisms behind the motion of these finite volume pockets following entrapment require further investigation. While a balance between drag and buoyancy is expected to control the motion of discrete air pockets in closed conduits, there have been limited studies in terms of how factors such as varying slopes, background flows, and air pocket volumes affect the air pocket motion. Past research by the authors presented at the 2012 ASCE-EWRI Congress indicated that for adverse conduit slopes, entrapped air pocket celerities can be approximated as the summation of the celerity measured in quiescent conditions and the ambient flow velocity. The present work aims to advance this research by including a wider range of experimental conditions, particularly horizontal and favourable slope conditions. Results of pocket celerities and trajectories are systematically compared for various tested slopes, flow rates, and pocket volumes. These experimental results will be useful to the future development of numerical models that can include the motion of entrapped air pockets in tunnels.

This paper presents a new analytical approach for the solutions of suspended sediment transport in channels using generalized integral transform technique (GITT). Compared with previous work, this new analytical solution approach takes into account the arbitrary distribution of turbulence eddy viscosity and the boundary conditions at the free surface and the bed. After developing the solution using GITT technique, we also present a library of analytical solutions for suspended sediment concentration considering the effects of different eddy viscosity distributions, vertical variations of mean flow distribution, bottom boundary conditions, etc. Finally, the results from this analytical solution are compared with numerical simulations.

Now there are many pipelines to deliver liquid-like water diversions in the world. Optimal route for pipeline transportation is a major concern for engineers, economists, and decision makers. Pipeline route selection is governed by many factors such as the shortest distance between supply and demand points, constructability, affordability, environmental impacts, and approachability. There are many methods developed for the pipeline route selection like Gestalt method, land suitability mapping techniques, geographic information systems (GIS), imaging technologies for pipeline mapping with the use of airborne lidar, etc. But these methods, though robust in translating physical constraints into feasible alternatives for route location, have their own pros and cons for applications, which are weak in incorporating the decision maker's preferences. This paper presents an easy approach to route selection with the goal of saving energy and having the shortest distance. The method in this paper makes an attempt to establish a method for the route with minimum energy required with the aid of mathematics computing and GIS or the data coming from Google Earth. This method is demonstrated here through two different case studies of pipe route selection, the Los Angeles aquaduct, the second Los Angeles aquaduct in USA, and water diversion from Palmer to Millbrook Reservoir in Australia. The calculated results are shown and analyzed.

The ARKStorm II Emergency Planning and Response Exercise was a joint effort of Ventura County Public Works Agency (VCPWA), Federal Emergency Management Agency (FEMA), and United States Geological Survey (USGS). It is a FEMA RiskMAP pilot project designed to showcase how scientifically based watershed modeling of a large and plausible storm event can enhance disaster response and mitigation planning and foster public awareness. The inundation mapping for this project was developed using hydrological and hydraulic modeling based on data from two severe and rare storms on record for the Santa Clara River (SCR) watershed, namely the 1969 and 1986 extreme precipitation events. The rainfall data was provided by the USGS; these data represent the last two catastrophic flooding events that occurred in Ventura County, California. Using the rainfall data, hydrologic time series of flow (hydrographs) for each of the major tributaries of SCR were developed and used for hydraulic modeling. Real-time storm progression results from the hydraulic modeling were developed to mimic realistic expectations of where flooding is most likely to occur, the resulting flood depth, and what critical community facilities and public and private infrastructure along the Santa Clara River are projected to be adversely impacted at specific time intervals during the storm event. For example, which transportation evacuation routes, bridges and underpasses, and designated community gathering places could become inaccessible due to flooding and flood-induced landslides at a predicted time interval (e.g., 30 hours into the storm). With such information in hand, alternate routes and public gathering locations would need to be identified through coordinated emergency planning and response exercises by the participating responsible officials of the County of Ventura and Cities along the SCR, FEMA, and USGS. Flood plain maps showing the extent of inundated areas with simulated water depth, critical facilities and utilities flooded, and real photographs of the destroyed areas along the SCR in the 1969 and 1983 floods were prepared to dramatize the events and make it as realistic as possible during the course of the workshop exercise. The main objective of this exercise was to determine which course of actions the county and city emergency planners and engineers would need to take to be better prepared for responding to such a disastrous event. This paper will focus on the hydraulic modeling, flood plain mapping, and the day-long emergency planning and response exercise for this joint effort.

In study was conducted simulation by CFD tool, flowing in a pipe of a hydraulic network side water supply by issuing a free jet through an orifice in a nozzle installed in the outer cylindrical pipe. Analyzed with the tools of computational fluid pressure field occurred with hydraulic fluid. The results demonstrated consistent up according to the expected physically.

The Dalles Dam consists of a powerhouse, a concrete spillway, a navigation lock, concrete nonoverflow sections, an earth-fill embankment on the Washington shore, a rock-fill embankment on the Oregon shore, and fish passage and appurtenant facilities. This dam is one of the largest navigation dams in the United States; it is approximately 8,735 feet in length and more than 200 feet high. This paper will discuss the hydrologic and hydraulic approaches for the dam failure analysis. It will also focus on the breach characteristics and type of failure and nonfailure simulations that were used in the model analysis. This paper will also spotlight the water resource engineering assumptions and techniques that were used in the HECRAS and HECGeoRAS models.

The present work focuses on estimating suspended sediment concentration in rivers using sediment transport modeling coupled with wireless sensors. The vertical attenuation of light intensity within the water column of open channels with suspended sediment closely fallows the exponential Beer-Lambert Law but varies considerably due to sediment physical characteristics. Dimensional analysis is performed using principles of optical physics in a liquid and dimensionless arrangement of controlling variables to formulate a light attenuation number that includes sediment density, particle size, concentration, and attributes of the incident light. The light attenuation number is used to predict a dimensionless light attenuation coefficient that parameterizes the Beer-Lambert Law. Dimensional analysis results are tested for a range of laboratory and field data of light attenuation by sediment in rivers and lakes reported in the literature and laboratory data collected in this study. We used our recently developed light attenuation sediment sensors for stream sediments in the lab to collect data results for natural and engineered sediments. Results show that the light attenuation number predicts well data across a range of sediment characteristics. And, implications are that knowledge of sediment properties allows the light attenuation number combined with sensor measurements and transport models to predict suspended sediment concentration in rivers. We also highlight that the low-cost wireless light attenuation sediment sensors are well suited for sediment measurements within watershed sensor networks that can be coupled to more traditional sediment transport modeling approaches.

It is essential to know accurately characteristics of the flow over stepped spillways such as turbulent dissipation and flow regime. This study was concerned with application of FVM-ANN technique for investigation of the flow regime over broad-crested stepped spillways. For this purpose, finite volume method (FVM) was employed for numerical modeling of stepped spillways using laboratory data belonging to a previous research study. The perfect conformity of numerical and laboratory results is clearly observed according to a statistical test. Then, for development of the numerical model, different geometries of spillways were investigated and flow regimes over these spillways were obtained. Furthermore, it has been attempted to train an Artificial Neural Network (ANN) that includes two layers and entails one neuron on output layer using numerical results in addition to investigating the number of neurons at the first layer. As a result of using ANN, the flow regime can be evaluated by having the discharge per unit width over the spillway, the steps' height, and the channel slope's angle. Finally, the sensitivity analysis of the flow regime against the change of each parameter of geometry of the spillways was done. Results indicated the behavior of the flow regime against investigated parameters well.

Circulation and thermal regime in Green Bay have important consequences for water quality, contributing to hypoxic conditions during the summer. Currents and temperatures in the Great Lakes exhibit a wide range of time and spatial scales, in response to atmospheric forcing, Earth's rotation, and geometry. Because of the interaction of drivers, water exchange between Green Bay and Lake Michigan has effects on water quality that are at least as important as those of watershed discharges. We are using field methods, hydrodynamic modeling, and frequency domain analysis to investigate the different drivers. Field methods showed that currents simultaneously flow in and out of the bay at different depths, and changes in temperature can be explained by oscillating influx of cold lake water at lower depths. We calculated spectra of temperature measured in summer 2011 in southern Green Bay, and of water currents across the mouth between the bay and the lake, simulated during the same period. Both sets of spectra showed numerous significant oscillations at frequencies higher and lower than the inertial frequency of about (17.5 h)-1. The higher frequencies include several of first few surface modes of Green Bay and Lake Michigan. A low frequency was also observed, with a period of 8-10 days, which previous studies explained as the first internal mode of Green Bay. Hydrodynamic model simulations showed that water exchange is significantly higher for winds blowing from the west than it is for winds blowing from the east.

This study examines the influences of curvature-driven and topography-driven secondary currents on the shifting or redistribution of primary flow in sine-generated meandering channels by using CCHE2D - a depth-averaged two-dimensional hydrodynamic and sediment transport model. Calculated results are compared to data measured in two sets of published laboratory experiments that investigated the characteristics of curved flow under well-controlled boundary conditions including steady flow and uniform-size bed material. The two sets of experiments, i.e., da Silva (1995) and Termini (2009), are selected as the representatives of immobile and mobile bed cases, respectively. Calculated results indicated that the shifting of primary flow from inner to outer banks in the curved channels is dominated by topography-induced current rather than the secondary flow driven by curvature. This understanding of the relative impacts of curvature and topographic-driven secondary currents will improve the understanding of flow structure in meanders and stable channel design.

Turbidity currents occur often at Shihmen reservoir in Taiwan, which has experienced increased sediment delivery over the last two decades. Due to limited sluicing capability, a major portion of the fine sediments have deposited in the reservoir causing a significant loss of the storage capacity. Further, extreme events have produced such high sediment concentrations that water supply has been interrupted causing unexpected economic and political turmoil. Various projects have been proposed and/or started to extend the reservoir life and maintain water supply. In this study, a two-dimensional (2D) layer-averaged turbidity current model is developed; the calibration and application of the numerical model to Shihmen reservoir is reported. The study finds that the developed turbidity current model, with appropriate calibration, predicts well the turbidity current movement and the sediment deposition pattern.

Chosui River in Taiwan has been subject to a large amount of yearly vertical and lateral geomorphic changes. Costly efforts have been made over the years for river maintenance, water delivery, and flood prevention. In the last decade or so, extensive studies have been initiated to seek whether numerical models may be used to predict river morphological changes so that potential risk areas may be identified, project alternatives may be evaluated, and project benefits may be assessed. In this study, the two-dimensional (2D) mobile-bed model SRH-2D, with its bank erosion capability, is used to simulate a 16.7-kilometer reach on the Chosui River. This reach is relatively complex and has experienced large lateral changes. There are measured data available for comparisons so that the numerical model may be evaluated. After a combined calibration and verification model over a seven-year period, the study shows that the coupled river channel and bank erosion modeling correctly captured major erosion and deposition locations and trends. It demonstrates that SRH-2D may be used for identifying potential erosion sites and providing information for river maintenance planning. Also, the bank erosion module is capable of predicting the bank retreat rate reasonably with only one major calibration parameter: bank erodibility.

In this paper the results of a numerical analysis on the effectiveness of slit-check dams in mountain rivers are reported. The temporal evolution of the sediment-related processes occurring upstream of slit-check dams was investigated by means of a numerical model based on the solution of the one-dimensional De Saint Venant-Exner equations. A comparison with literature data from laboratory experiments has shown the model to accurately reproduce the sediment transport processes as well as the evolution of the deposit upstream of the slit-check dam. Then, model simulations were performed to derive indications for the slit design as a function of the required check effectiveness of the dam structure.

To investigate the nonlinear behavior of fluid flow in the fracture, a set of numerical single rock fracture models with different JRC values and one with real rock fracture profile were built. Numerical simulations of single-phase water flow through these models under varying inlet pressure were carried out using COMSOL Multiphysics numerical simulator. Three kinds of joints roughness coefficient (JRC) values were applied to build these fracture models and to study the effect of the roughness of the fracture on the flow behavior. The numerical simulation results and the comparison test results show that the models could simulate the nonlinear behavior of fluid flow in single rock fracture effectively. Fracture roughness has significant effect on the nonlinear flow behavior in the fracture.

Applications of computational fluid dynamics (CFD) analysis are strongly limited by computing efficiency particularly for large-scaled and long-term problems. To alleviate the efficiency problem, parallel computing, decomposing a large problem into multiple small problems, and solving them concurrently or simultaneously (in parallel), is increasingly adopted. In recent years, graphics processing units, GPU, and particularly general-purpose computation on graphics processing units, GPGPU, have been successfully used for parallel computing in the areas of medical imaging, environmental science, and CFD, etc. The availability of a large number of processors greatly speeds up the efficiency of parallel computing. This study is aimed at parallelizing the implicit CCHE2D model (Jia et al., 2002). CCHE2D is a general depth integrated hydrodynamic model with sediment transport, water quality evaluation, chemical spill, and flood modeling capabilities. The flow model of CCHE2D is paralleled on GPU with CUDA Fortran programming techniques to improve its computational efficiency in personal computers (PC). Comparisons of numerical results and computing efficiency between the original sequential model and the parallelized model have shown that the parallelized CCHE2D model is consistent with the original model in producing reasonable results with significantly higher efficiency.

This paper presents real-time predictions of wind, waves, and coastal flows by using an integrated meteorological, coastal, and ocean processes model. The highly efficient computational performance of this model enables wind and storm surge forecasting in the northern Gulf coasts including the Louisiana/Mississippi/Alabama coastal regions and the major river systems such as the Mississippi and Atchafalaya Rivers. Simulations were done on a personal computer. In the prediction of wind fields, a newly developed tropical cyclonic wind and atmospheric pressure model is used to reconstruct wind field by taking account into the hurricane decay effect after hurricane makes its landfall. The predictions for four advisory tracks of ISAAC were started before the landfall of this hurricane on Aug. 29, 2012, by using NOAA's advisory track data and the H*wind data fields. The tracks used in the study are Advisory #27, 29a, 30a, and 39. The predicted wind and storm surge are compared with the real-time observations by NOAA gauges in the area. The real-time predictions of storm surges in Isaac caught the timing of the flood peak in the Gulf coasts. The model gives more accurate water levels when the hurricane was approaching the land and the track data become more accurate. It demonstrates that this model has a good feature both in computational efficiency and accuracy to be an operational forecasting tool.

Hydraulic study of a selective withdrawal relief gate is presented. A comparison study between a computational fluid dynamics model, Flow3D, and a 3D hydrodynamic model, EFDC, has been performed. Flow3D is applied to simulate behavior of the flow by using limited compressible flow approximations and RNG turbulence model. EFDC is used to analyze the flow through the inlet using a shallow water solver configured equivalent to 2D Reynolds-Average Navier-Stokes (RANS) equations in vertical plane and Mellor-Yamada Turbulence Closure Scheme. Pressure heads and vertical opening velocity results from both models are compared. Computational fluid dynamic models provide us great insight to determine the hydraulic behavior and flow properties in these complex geometries.

To develop an effective remediation and containment strategy for river oil spills, it is important to understand the fate and transport of the oil-contaminated sediment in the river. This paper presents an application of hydrodynamic and sediment transport model as an aid in planning, design, implementation, monitoring, and evaluation of future management method in case of an oil spill. The hydrodynamic and sediment transport characteristics of a 40-mile reach of the Kalamazoo River affected by the July 2010 oil spill were modeled using the numerical modeling program Environmental Fluid Dynamic Code (EFDC). The simulations provided a basis for evaluating the potential for sediment and associated submerged oil transport and subsequent deposition with flow events. The sediment transport model was used to assess the efficiency of the sediment trap structures under varied flow conditions and to select their best location and configuration.

The temporary belowground storage of stormwater is useful in urban areas to prevent flooding. During intense rain events the conduits can fill rapidly and completely undergo a transition from open channel flow to pressurized flow. This transition can create large discrete pockets of trapped air as the interface advances into the free-surface portions of the system. These pockets pressurize in the horizontal reaches of the system and then are released through vertical vents, potentially creating a geyser condition. There have been some experimental and numerical investigations of the geyser effect, but the complex nature of the physics and geometry make this a challenging problem. Numerical studies have treated the geyser as a lumped mass or rigid column, with no consideration to the multiphase flow dynamics. This work presents a preliminary finding of a multiphase flow numerical model to capture both the liquid and gas dynamics, as well as the necessary interaction to create the geyser.

Circular dropshafts, commonly used in urban storm water systems for energy dissipation and flow control, are characterized by significant flow aeration. In the laboratory, a series of experiments were performed in a circular dropshaft having two identical horizontal inflow and outflow circular channels having diameters of d=0.12 m, and a circular drop chamber having diameter of D=0.358 m for observing flow patterns and measuring air bubble entrainment flow parameters. Experimental observations showed distinct flow regimes associated with nappe impact in the shaft pool, in the outflow channel, or in the opposite shaft wall. New detailed air-water flow measurements were conducted in a circular dropshaft with using double-tip fiber optical probe. Measurements of void fractions, bubble frequencies, and bubble sizes were conducted for different flow conditions of the circular inflow channel. In the shaft pool, the results obtained from measurements demonstrated the complexity of different air entrainment mechanisms.

The term "sloshing effects" describes the impact of a seismic event on a container and its liquid contents. To prevent the accidental release of the contents of a container, container design must simultaneously accommodate the impulsive force of an earthquake on the rigid components of the container and forces generated by the resulting convective wave confined inside the container. California Accidental Release Prevention (CalARP) has issued guidance regarding minimum design parameters for this situation. CalARP's primary solution is to completely confine the convective wave within the container's freeboard, the space between the maximum static surface of the liquid and the roof of the container. In the case of potable water, this solution has undesirable side effects on water quality, system capacity, and corrosion prevention. CalARP's secondary solution is to accommodate the uplifting forces of the convective wave on the roof and the combined lateral impulsive and convective forces on the structure in the design of the tank. The objective of this paper is to develop an approach for explicit calculation of the lateral and uplifting forces of the convective wave and their superposition with respect to impulsive seismic forces. This approach is currently being employed in the design of a cylindrical steel potable water tank in California. The approach has been tentatively approved by the California Department of Public Health pending final design, and the eventual owner of the tank desires to incorporate the approach into the agency's design standards. Successful application will meet CalARP requirements, reduce construction materials, improve water quality, maximize system capacity, and reduce corrosion. In addition, application to seismic retrofit of similar water tanks may result in similar benefits and extend the infrastructure life cycle.

This paper investigates reduction in degradation downstream of broken-back culverts by forming a hydraulic jump. A model was built in the laboratory focusing on a drop between inlet and outlet of 18 feet. Three flow conditions simulated included 0.8, 1.0, and 1.2 times the culvert depth. The hydraulic jump created in the culvert is classified as an "oscillating jump." To locate the jump near the toe, different sill and friction block arrangements were tested. The length of the culvert was 150 feet. In the broken-back culvert, a slope of 1 (vertical) to 2 (horizontal) was used for ease of construction, with the flat part at a 1% slope. The best option to maximize energy dissipation is to use one 5 foot sill located 43 feet from the outlet. The length of the culvert can be reduced by 40 feet. The calculated energy dissipation of the culvert was 66 percent.

Stepped spillways can enhance dissolved air flow, which increases the rate of energy dissipation and reduces the size of the energy dissipater at the downstream of the spillway. This paper was concerned with the application of a feedforward two-layer artificial neural network (ANN) to evaluate the aeration efficiency over broad-crested stepped spillways corresponding to different types of the flow regime. After the training of different networks, the best network, which includes two layers and one neuron at output layer, was selected. According to obtained results, the aeration efficiency at 20° C can be evaluated by having the discharge per unit width over the spillway, the chute slope angle, the step height, and the total number of all the steps. The obtained network was validated using laboratory data, and the proper conformity was clearly observed statistically. Furthermore, ANN results were compared with the Adaptive Network Based Fuzzy Inference System (ANFIS) results. Finally, the sensitivity analysis of the aeration efficiency against the change of each parameter of geometry of the spillways was done. Results indicated the behavior of the aeration efficiency against investigated parameters well.

This article presents an artificial intelligence approach for predicting hydraulic properties of circular buoyant jet entering in the static ambient flow by coupling artificial neural networks and ANFIS. In many cases due to high concentrations of pollutants, or critical toxicity, or even very high temperature wastewaters from nuclear reactors, dilution of wastewater to reach the limit concentration should be done in the shortest time. One way to make quick dilution is using submerged jets in rivers or seas that can relatively quickly dilute large amounts of pollution and due to its mixture of high turbulence conditions, the destructive effects will rapidly reduce. Jet behaviors are very important in the environmental field and real ambient flow. Characteristics of jet diffusion, mixing length, distribution of concentration, jet core velocity, and trajectory of jet are variables that should be considered in the buoyant jets. The flow of jet is heavily dependent on the velocity and on the geometry of the diffuser and the physical properties of ambient flow. In this study, drawdown trajectory of jet has been investigated. To achieve goals of this research program, four input variables have been chosen, including relative length of jet trajectory, X/dp, in which X is length of positive buoyancy and dp is port diameter; jet convergence angle θc; geometry number of jet, Di/dp; and Densimetric Froude Number, Frd. In addition, relative height of jet trajectory, Z/dp was selected as output variable. In this article, a series of experiments (from the physical model in the hydraulic laboratory of Shahid Chamran University, Ahwaz, Iran) were used as the learning data for artificial neural networks and ANFIS. The best-trained network of ANN was compared with results of ANFIS. It should be noted that different topologies have been undertaken by using ANN and ANFIS for upper and lower boundaries of jet flux. Thus, two values for Z were predicted. Findings show that ANFIS can predict upper and lower boundaries values of jet trajectory better than ANN. By considering the results, the values of RMSE for the best-selected topology are equal to 0.0051, 0.0076, and 0.0076 in training, validating, and testing mood respectively for upper boundary, moreover 0.0047, 0.009, 0.0058 in training, validating, and testing mood respectively for lower boundary.

Recent experience has shown that relatively minor interaction between regions of flow separation can have a significant impact on water level oscillations in pump intake structures. Intake structures that appear to follow established design guidance have exhibited periodic water level oscillations of up to 1 meter or more. This can have a negative impact not only on the approach flow to the pumps but also on the operating conditions such as submergence and NPSH. This paper presents the results of several recent physical model studies that identified large-scale water level oscillations. A sensitivity analysis has been conducted, and common features between intakes that appear to contribute to the oscillations are presented along with relatively simple remedial measures. Recommendations on how to avoid oscillating water levels are presented and discussed.

Studding of contamination and water mixing is important for rivers management. Beds form as dunes and vegetation affect the advection process. The main objective of this research was investigation of transverse mixing coefficient (TMC) and dominant factors on the coefficient simulated in a river containing vegetated walls. Experimental measurements were made over 5-10 dunes in a series of 10 of two-dimensional asymmetric gravel dunes. Experiments were carried out in a flume with a 20 m long, 0.6 m wide, and 0.6 m deep. The dunes had an angle of lee slope of 28°, a mean wave length of 1 m, and mean height of 0.08 m. Three flow depths of 280, 330, and 360 mm were used for evaluation of aspect ratio. The result shows that interaction of vegetation and dunes can increase mixing of contaminant and TMC 3.19 times on flatbed. Investigation of flow structure shows that influencing factors on TMC in this case are intensity of turbulence, shear velocity, and secondary flows.

Wastewater pump stations are an integral part of our nation's critical but aging infrastructure, and many of these stations are approaching the end of their originally planned design life. As with many critical infrastructure components, budget-strapped communities are looking to not only extend the life of these systems but to also increase the capacity. In many cases the systems are being asked to operate in conditions that were not anticipated during the original design. For example, significant development may be resulting in significantly larger than anticipated grease and grit loads, which results in increased maintenance and operational down time. Stations that may have been designed for slow-moving approach flow to allow for entrained gases to rise to the surface may be providing the ideal environment for grease and sediment accumulation. Municipalities are continually faced with the need for additional capacity and with limited budgets, many are choosing to rehabilitate and increase the capacity of existing stations.

Risk-informed approaches require loading curves for hazards including seismic and hydrologic loading. Current design standards for dam safety are based on the Probable Maximum Precipitation (PMP) and Probable Maximum Flood (PMF). Numerous studies have been completed attempting to place an annual chance exceedance (ACE) on the PMF. The results of these efforts range from about 2x10-4 to 1X10-9, with the second frequency being well beyond what is thought credible in the current literature. This raises the question: We can mathematically extend frequency curves out to 10-9, but should we? This paper will discuss the uncertainty associated with these estimates, the variation in these estimates, and why estimating the ACE for the PMF may not be a prudent effort.

Management of sediment within watersheds disturbed by human activates is vital for the biological protection of our nation's waterways. Excessive fine sediment in rivers and streams is the most cited cause for water quality impairment in most states, leading to the development of total maximum daily loads (TMDLs) for 303d listed waterbodies. Understanding the potential sources of fine sediment generated by erosion processes that change from headwater areas to lower river reaches is important in the development of effective watershed management strategies. These strategies need to regulate sediment transport within natural ranges that support native lotic biota. Reviews of the erosion processes from field-scale overland (sheet) flow, shallow concentrated flow, first-order gully and headcuts, and stream channel bed and bank were examined, and differences defined. Recognizing the process differences and the potential sediment yields per watershed location provides a mean to assess whether restoration efforts are best implemented. Overall, this paper summarizes different erosional processes along a river continuum, describes how scale can skew sediment yield estimation, and elaborates on how scale can alter which best management practices are used.

Prediction of total sediment load has been a challenge to river engineers for decades. Two approaches are typically used: One is to directly calculate the total sediment load from measured flow and sediment properties, and the other is to separate total sediment load into bed load and suspended load and calculate them independently. Because the criteria that separate bed load and suspended load is still a debatable subject, practical engineers prefer to use the total load equation for estimating sediment load. However, there are more than 31 equations for calculating total sediment load, and the discrepancies of those equations are in the orders of magnitude. To obtain a general equation, this study analyzed more than 4,000 sets of laboratory experimental and 3,000 sets of field measurements of total sediment load. Based on the dimensional analysis, eight new dimensionless parameters are formulated to quantify total sediment load. Correlations of dimensionless total sediment load with those new and other conventional parameters are calculated using the observed data. The highest correlation, 0.94, was found between the dimensionless total sediment load and a new dimensionless parameter, τ* (u* - u*c) / ω , in which u* is shear velocity, ω is settling velocity, and τ* is dimensionless shear stress. A simplified power-law relation is formulated from fitting the measured data. This new relation is compared with the commonly used total sediment load relation, such as Engelund-Hansen (1967), Ackers-White (1972), Yang (1973, 1979). Results showed the new simplified equation yielded the best matches of this set of total sediment load data.

Lost Creek is a tributary of the Wabash River and runs directly through the campus of Rose-Hulman Institute of Technology (RHIT) in Terre Haute, Indiana. Students have been collecting survey and water quality data along Lost Creek for the past three years as a part of a pre-restoration monitoring program. We expanded the database of pre-restoration conditions by characterizing transient storage and nitrate uptake under current conditions. In doing so, we have a baseline to compare any increases or decreases in storage and uptake due to possible future implementation of restoration techniques. In the summer of 2011, students conducted several nutrient injection tracer studies of sodium chloride and potassium nitrate on a study reach of Lost Creek that runs through campus. We continued this study by modeling solute transport of the 2011 tracer injection data collected at two different discharges with the One-Dimensional Transport with Inflow and Storage model (OTIS). The resulting modeled parameter estimates showed greater transient storage along the reach at the lower of the two discharges that were modeled. Because we only have data from two injections, we can only compare the results of these two particular studies and cannot extrapolate beyond our collected data to make inferences on general trends at this point. By collecting more data through future injections, we can establish more conclusive baseline conditions to inform pre-restoration monitoring efforts.

Bed load transport rate can be calculated by using the particle velocity of transport sediment. However, few experiments have been conducted to directly measure bed sediment velocity. This paper presented a series of experiments conducted at an open channel flume to study bed load particle velocity at different stages of transport intensity. The flume is 13.5 m long and 0.6 m wide with a fixed bottom slope of 0.001. Four groups of uniformly sized sediments with mean sizes ranging from 0.45 mm to 4.75 mm are used. Flow discharge is measured at the end of flume using a rectangular weir ranging from 0.015 to 0.055 m3/s. The vertical distribution of flow velocity is measured using the Vectrino Velocity Profiler with a sampling frequency of 70 Hz. Bed load particle velocities are determined by particle tracking analysis of a series of images captured using a high-speed camera. The spatial and temporal averaged particle velocities and the statistical distribution of velocities are calculated and compared with empirical relations. Results showed that the spatial averaged particle velocity is much smaller than the saltation velocity of a single particle. A new linear relation for particle velocity is formulated based on the experimental data. Additionally, both measured particle velocities and transport directions nearly satisfy the normal distribution. Those experimental data for particle velocity provide opportunity to improve prediction of sediment transport.

Knickpoints are geomorphic bed features characterized by the formation of a sharp change (i.e., knick) in the channel slope leading to the creation of a wide crest staircase. Knickpoints migrate upstream and cause bank instability, exposure of bridge-crossing foundations, and the deterioration of fish habitat. They are a common geomorphic hazard in many streams of the Midwestern United States that is partly due to prevailing management practices, including stream channelization, which mostly occurred during the first half of the 20th century. Over the last 40 years, local governmental agencies have attempted to halt knickpoint migration by constructing different types of grade control structures (GCS). Despite these attempts, the problem still persists. Understanding of the mechanisms triggering the onset of knickpoint migration is at a primitive stage. In this study, a field evaluation of a representative channel reach containing a knickpoint in the Deep Loess Region of western Iowa was used to test current theoretical and numerical models of knickpoint migration. Continuous stage and periodic flow measurements were recorded for almost two years and included an extreme event, which occurred during the catastrophic 2008 Midwestern United States floods. In addition, soil samples from the river bed and banks were collected and the bathymetry was measured to fully characterize the stream reach. The data were used to estimate the parameters of various models to quantify the knickpoint migration rate and evolution during various hydrological events. The final goal of this research is to identify the most suitable approach to model the knickpoints found in Midwestern streams. The results of the study can then be used by federal or state agencies to define better plans for the future control of bed degradation using more adequate GCS.

Stream restoration for water quality and nutrient management relies on effective assessment methods that measure the before-and-after improvement of water quality, or lack thereof, from implementation. We present a water quality and nutrient modeling tool for potential use in such applications. The model is applicable to low-gradient streams and watersheds with agricultural and urban land use such as those found in the Ohio River Basin, which tend to have relatively high DIN inputs to the stream channel and a need for water quality restoration. The model is unique in that it makes use of nitrogen stable isotopes for constraining the nutrient budget; and we model rates of nutrient removal by the streambed associated with restorative measures. A mass balance nutrient model that simulates the nitrogen cycle, e.g. uptake rates, nitrification, denitrification, and ammonification, is coupled with a nitrogen isotope mass balance model, and associated Rayleigh fractionations, for transported sediments and streamwater DIN. We formulate and then apply the model for the South Elkhorn Creek, a stream in Kentucky, USA, affected by both urban and agricultural land uses, which has undergone restoration in recent years. The stable nitrogen isotopic signature of sediment (δ15NSed) was measured to verify the model. Preliminary results of the study highlight that the fate of the benthic sediments dominate the isotopic signature with δ15NSed being highly dependent on the streamwater DIN isotopic signature (δ15NDIN) and fractionation associated with uptake and denitrification processes. Preliminary sensitivity analysis shows that the isotopic signature is extremely sensitive to uptake and denitrification rates highlighting its effectiveness to assess if nitrogen is being fully removed from the stream system. Model estimates show that the system efficiently removed ammonium from the streamwater during all seasons. The model advancement of coupling the isotope fate model with the unmixing model provides a potentially powerful tool to constrain the nitrogen budget for watersheds with comparable characteristics. However, testing is needed in restoration projects, which are part of our ongoing research.

This study simulates flow hydraulics, sediment transport, and bed deformation in a large-amplitude meandering flume using CCHE2D, a depth-averaged two-dimensional hydrodynamic and sediment transport model. The planform of the flume is a sine-generated channel with a deflection angle 110° in terms of experiments by Termini (2009). The bed material in the flume is treated as uniform grain-sized sediment and simulated by Wu (2001)'s sediment transport module. Changes in bed elevation are calculated by solving the sediment mass conservation equation. The model is calibrated by comparing the computed results with the observed bed deformation after 150 min. In the numerical experiment, the most pronounced erosion and deposition areas initially occur right above the apex and gradually extend downstream with time. Most sediment is removed from the outer bank deposits at the next bend, but the front crosses the centerline around the apex to complement the scouring.

Post-construction data following streambank restoration and stabilization projects are currently lacking relative to the resistance of cohesive streambanks to geotechnical failure and fluvial erosion. This research sought to quantify differences in erodibility and geotechnical properties of natural and restored banks after construction. The streambank environments varied with respect to the presence or type of construction and resulting bank slopes. Streambank conditions included modified fill bank plots, modified cut bank plots, and nonmodified control bank plots. Geotechnical resistance to failure was quantified using the Iowa borehole shear test (BST) to measure the in-situ drained shear strength of soils. Fluvial resistance to erosion was measured using an in-situ "mini" jet erosion test ("mini" JET) to estimate the erodibility coefficient and critical shear stress. Bulk densities were affected by construction activities with a general trend toward higher bulk densities with greater construction modification. Geotechnical strength, in terms of the soil's effective cohesion for the modified fill bank plots, differed between the modified cut bank plots and the nonmodified control plots but additional samples are needed for statistical relevance. Surprisingly, fluvial resistance to erosion may not be influenced by streambank modification based on "mini" JETs conducted to date. Variability in fluvial resistance parameters within each treatment was as large as differences between treatments. These modifications to the streambank fluvial and geotechnical resistance properties should be considered when modeling the impact of stabilization practices on streambanks.

River meandering could endanger transportation infrastructures by lateral expansion and down-valley translation of meander bend. In this study, we used the RVR Meander package for four bridge crossings in Texas where the meanders have moved considerably over the past several decades. These bridge crossings are over the Brazos River, the Nueces River, the Sabine River, and the Trinity River in Texas. Widely used meander migration model developed from Ikeda et al. (1981) was adopted, which relates migration rate (M) to vertically averaged near-bank velocity (ub') through the use of a coefficient of bank erosion (E). This study attempts to calculate E values for eroded banks from measured long-term migration rates and computed near bank velocities. The calculated erosion coefficients were then used for the prediction of the future location of meandering streams. The advantages and limitations of the approach are discussed focusing on the capability of predicting the planform evolution of natural rivers.

The Sheboygan River discharges into Lake Michigan at the City of Sheboygan, Wisconsin. In 1985, the lower Sheboygan River and Harbor was designated an Area of Concern (AOC) by the U.S. Environmental Protection Agency. The City of Sheboygan, Sheboygan County, and the Wisconsin Department of Natural Resources are implementing the Sheboygan River AOC Habitat Restoration Projects to address habitat-related beneficial use impairments (BUIs). The overall objective of these projects is to transform degraded areas and restore the natural habitat functions of the river corridor using various bioengineering techniques. The projects will stabilize eroded stream banks and improve shoreline habitat for fish, herptiles, birds, and wildlife. Invasive species management is also a major component of the restoration plan. Three sites were targeted for restoration including: (1) the Taylor Drive/Indiana Avenue Site, (2) the Wildwood Island Site, and (3) the Kiwanis Park Site.

The Des Moines River caused excessive bank erosion at two different sites in Van Buren County, IA USA. At the first site, the observed bank loss occurred along a 600 ft. straight stretch at the left bank and was induced by a recent channel enlargement. In the second site, a 1,800 ft. stretch along the right bank was destabilized by the higher velocity downstream of a river bend. To mitigate this problem, the alternation of stream barbs and spurs was proposed at both sites. The combination of barbs and spurs has been already proven to be an effective approach in controlling streambank erosion at different locations along other large rivers in Iowa with similar geomorphic features. However, their design is site specific and each application needs to be carefully evaluated. A commercially available two-dimensional depth-averaged model (FESWMS) was used to evaluate the efficiency of various scenarios and to determine the optimal number of structures. Field surveys together with laboratory experiments were used to calibrate and validate the numerical model. The effect of the structures on the local flow field was taken in account adjusting the value of the eddy viscosity. Sensitivity analysis of eddy viscosity and Manning's roughness coefficient was performed to establish the uncertainty in the output of the numerical model. The strategy followed in this case study will help county engineers to identify an optimal design, which is at the same time efficient and cost-effective, to reduce bank erosion.

A primary mission of the U.S. Army Corps of Engineers (USACE, Corps) is to manage the nation's water resources. The Corps performs this mission across multiple purposes at the direction of the United States Congress. To satisfactorily meet these sometimes conflicting purposes, both now and in the future, it is critical that the nation's water resources are studied and managed in a holistic and comprehensive approach. Several tools have been developed to study and manage our nation's water resources both from a planning and a real-time water management perspective. The suite of water management tools is the Corps Water Management System (CWMS) and the overarching tool to perform alternative analyses is the Hydrologic Engineering Center's (HEC) Watershed Analysis Tool (HEC-WAT). While these tools exist, unfortunately the Corps has not consistently applied these state-of-the-art tools across the nation. Even though the technical capabilities exist, the resources did not. This paper introduces both tools and describes new efforts that are attempting to implement these tools and why it is critical that these tools be applied consistently. In addition, a new multi-agency effort that will bring the technical resources of three Federal agencies closer together to address real-time and planning-related water resources issues will also be discussed.

Climate change implications and the associated risk and uncertainty in the design and evaluation of infrastructure is an increasing concern facing system owners and engineering design professionals. This paper provides a discussion of a project-level adaptation design process that provides a context for inclusion of climate change uncertainty. The adaptive design process proposed is for the analysis of infrastructure affected by precipitation, runoff, and flooding, but the basic framework can also be used to evaluate other climate hazards such as sea level rise, urban heat islands, etc. The process in this paper focuses on the flooding of transportation infrastructure, in particular a bridge crossing. However, the process can also be readily modified to analyze other forms of infrastructure including sewage treatment facilities, levees, dams, etc. The adaptive design process is a site-specific, detailed evaluation that relies upon the testing of different project alternatives. Multiple alternatives are to be developed and tested for a range of peak discharges associated with future climate projections and/or error margins in historic precipitation data. The process analyzes each project alternative using hydrologic damage curves that relate asset failure thresholds (and their costs) to specific discharge levels. The damage curves are to be developed by planners, economists, and design professionals based upon sound engineering judgment and an analysis of the implications of failure. The adaptive design process can be utilized as a tool to evaluate the uncertainty in system hydrology due to projected climate changes and/or the error margins in the historic climate record. The adaptive design process concludes with a cost-benefit economic analysis. The economic analysis provides the basis for cross-comparison among the adaptation alternatives. The project alternative with the highest benefit/cost ratios across the range of climate scenarios tested should receive strongest consideration for final design.

A GIS-based fully distributed rainfall-runoff model has been developed on the basis of SCS-CN method for computing daily runoff at grid level. Grid map preparation for the study area with a square grid size of 1 km x 1 km has been carried out in GIS environment. The study area has been divided into 2,785 grids. The average yearly runoff was estimated for the period from 1996 to 2006 as 40.12% of rainfall for the study area. Maps pertaining to runoff, geomorphology, soils, groundwater potential, slope, and land use/land cover spatial maps have been integrated in GIS environment and the composite land unit map has been derived. It provides an effective summary of the characteristics or attributes related to topography, hydro geomorphology, soil, drainage, and land use. By careful examination, decision rules were applied through the model on each grid element of the integrated coverage taking into account the existing land-use practices, the suitability of soils, and the availability of surface and ground water potential to create the action plan suggesting alternate land use practices of the study area. The alternate land use practices such as agro-horticulture, horticulture, intense agriculture, silvipasture, and forest gap plantations have been suggested at grid level. These recommendations will result in better information and coordination activities essential for successful implementation of sustainable water resources development and management activities.

Public water suppliers across Florida have historically depended upon on inexpensive, fresh groundwater from the Floridan aquifer as their primary drinking water source. Based on major surface watershed boundaries, the state is divided into five Water Management Districts (WMDs) that regulate activities that affect the waters of the state and issue water use (or consumptive use) permits to water users. The Central Florida area is divided among three WMDs: the St. Johns River Water Management District (SJRWMD), the South Florida Water Management District (SFWMD), and the Southwest Florida Water Management District (SWFWMD). In 2006, during a period of very rapid population growth, these three WMDs concluded that the increased use of the desirable groundwater sources would not be sustainable (WMDs, 2006). Therefore, they embarked on a multi-year, multi-phase process to develop alternative water supplies (AWSs) and modify water resource management tools and regulations for the region.

New Castle County operates a separate sanitary sewer collection and transmission system in Delaware consisting of approximately 1,600 miles of gravity sewers, 200 miles of force mains, and 165 pump stations. Much of the modern interceptor system was built through the Construction Grants Program in the 1970s and 1980s. Some of this system, particularly in the Brandywine Hundred Watershed, has now failed due to hydrogen sulfide corrosion and other issues, while some has exceeded its design capacity. After extensive sewer rehabilitation, some interceptors would still have insufficient capacity for the design wet weather event and therefore need to be replaced. A Secretary's Order from Delaware's Dept. of Natural Resources and Environmental Control (DNREC) requires that these issues be resolved. This presentation describes the planning and design of a dual interceptor system to replace a failed and undersized interceptor. The smaller pipe carries the dry weather flows and the parallel larger pipe carries the design wet weather flows. The system is designed with ease of operation and maintenance as a high priority.

Across the country, many public agencies, including state DOT highway divisions, which own and operate municipal separate storm sewer system (MS4), are facing increasing pressure in meeting the EPA's TMDL or Waste Load Allocation (WLA) requirements. TMDL/WLA implementation is creating additional work load and financial burden for many highway agencies as they try to meet conditions of their existing NPDES/MS4 permits with limited resources. EPA enforcement of TMDL compliance varies from region to region; some were expressed in TMDL implementation plans, while others impose numeric WLAs to the MS4 permit holders. The regional variation of the TMDL requirements influences the strategies and approaches the MS4 permittees choose in TMDL implementation. This paper highlights the TMDL compliance strategies of four different agencies; located miles apart, each have their own unique features yet all utilize a multi-set tool box to achieve compliance.

There is significant evidence that altering river flows downstream of reservoirs harms native aquatic ecosystems and decreases the ability of native species to strive and survive. Innovative water management is needed to improve the health of native aquatic species and their surrounding ecosystems while maintaining the benefits from historic operating policies at these facilities. The Connecticut River is the largest river basin in New England and one of the most impounded rivers in the United States. Five hydropower facilities along the Connecticut River are undergoing Federal Energy Regulatory Commission (FERC) relicensing. These facilities respond to both seasonal and hourly power demands. This relicensing process provides an opportunity to explore and alter the operations of these facilities utilizing coordinated reservoir management practices that investigate different operating objectives. This study presents an optimization model that investigates the value of coordinated reservoir management practices for ecological benefits at the major reservoirs undergoing relicensing. Optimization models have a long history of application in reservoir operation studies. One important use of optimization models on large-scale water management projects is to trade off different operational objectives of hydropower facilities. This research explores the use of optimization models in reservoir operations to address objectives related to emerging environmental concerns in the hydrologic regime while addressing historical operating objectives for management of hydropower reservoirs in the Connecticut River. Results suggest that coordinated operational changes to current hydropower reservoirs can restore some aspects of the natural hydrologic regime necessary for ecosystem persistence without considerable losses to current economic benefits.

In the past, Central Arizona Project (CAP) has implemented different planning applications such as long-range forecasts to determine water storage needs, financial planning, and drought preparedness. Currently, CAP is incorporating a holistic water resources planning program that includes Integrated Resource Planning (IRP), Scenario Planning (SP), and the utilization of Decision Support System (DSS) modeling tools, etc. Within the DSS framework, CAP is using the RiverWare-platform-based Colorado River Simulation System (CRSS) and System Dynamics (SD) modeling environments to assist in CAP's water resources planning activities. This analysis focuses on presenting the implementation of two DSS models to create and simulate a variety of plausible scenarios under the context of CAP's water resources management objectives. These tools will be instrumental in providing decision-making support, and will provide information that can be used to define the optimal solutions that address the issues that CAP manages. Water resources DSS modeling tools will continue to be of great importance for areas in the Southwestern United States that are prone to climate variability, including droughts.

Watershed degradation caused by human development has become an increasing concern in certain areas of the country where clean water is important not only for the economy, but also for maintaining a high standard of living. As a result of environmental degradation in the Chesapeake Bay watershed, local, state, and federal agencies have developed regulations aimed to address poor water quality and restore the Chesapeake Bay ecosystem. In 2011, the Chesapeake Bay Program (CBP) assigned nutrient and sediment load reductions to individual states and ultimately local jurisdictions to achieve environmental restoration in the Chesapeake Bay. As a result, local jurisdictions must develop a plan to meet nutrient and sediment load reductions in a number of different watersheds, which vary in size, population, and physical characteristics. Baltimore County, Maryland, consists of 14 major watersheds covering more than 680 square miles. Containing a variety of land uses ranging from highly urban to agricultural, Baltimore County has chosen to focus on Small Watershed Action Plans (SWAPs) to address the watershed restoration. A SWAP identifies strategies including a combination of government capital projects, actions in partnership with local watershed associations, citizen awareness campaigns, and volunteer activities for bringing a small watershed into compliance with water quality criteria. This paper will discuss how the restoration planning process is conducted to address Total Maximum Daily Load (TMDL) criteria for pollutants of concern in watersheds while also addressing local environmental concerns through the use of field assessments, GIS analysis, and pollutant load reduction planning. Parsons Brinckerhoff has worked with Baltimore County to develop a number of SWAPs, including one completed in 2012 for the Middle River and Tidal Gunpowder (MRTG) watershed. As a case study, this paper will specifically discuss the process for the development of the Middle River and Tidal Gunpowder SWAP, addressing a 19-square-mile watershed surrounding Essex, MD. The planning process includes a characterization of the unique natural and modified characteristics of the watershed, identification and calculation of existing pollutant loadings from uplands areas, and identification of potential projects to reduce pollution from runoff. Potential restoration actions are assigned an implementation schedule that provides cost estimates, sets measurable milestones, and distinguishes watershed partners responsible for completing restoration tasks, serving as a roadmap to restoration. Through focusing on a small, unique watershed, the Middle River and Tidal Gunpowder SWAP outlined 11 major goals with input from the community that defines a local vision for a healthy ecosystem. Highlighted by 71 specific restoration actions with an estimated cost of $18,460,000, Baltimore County can begin implementation of the SWAP to meet mandated pollution reduction milestones by 2017 and 2025.

The rural highlands of Guatemala is a popular destination for American tourists who visit the area for both recreation and for the opportunity to participate in social works programs. One of the challenges associated with studying in the region is the need to maintain a fraternalistic mind-set as opposed to the sometimes more prevalent paternalistic approach. Safe drinking water is in relatively short supply in the highlands, and students and faculty from the Missouri University of Science and Technology have been conducting drinking water studies in the area for more than a decade. The majority of the students have been engineering students, and while women typically make up less than 25 percent of engineering enrollment, the majority of the S&T publications about Guatemala water have been authored by female students.

As one of the most important renewable resources, small hydropower is also an emphasized project of the Clean Development Mechanism (CDM), which has been greatly developed and of great importance to alleviate the energy crisis resulting from the rapid economic growth of China in the past few decades. The impact on power grid is more and more obvious as most small hydropower plants operate on a river run-off system and generation output variation is very large between wet period and dry period. In the meanwhile, the operation and management of small hydropower in China have many outstanding problems due to the history and other reasons. Taking Yunnan power grid as the background, in this paper attempt has been made to explain the influence on safety and stability of power grid after large-scale small hydropower in operation. First, detailed description of the situation of small hydropower in Yunnan power grid. Second, combined with the actual circumstances, analysis of the problems and challenges that the power grid faces is presented. Finally the corresponding solution measures are put forward.

In China, about 70% of hydro resources are concentrated in the southwestern regions, and single provincial hydropower system is mainly constituted by several large-scale mainstream cascaded hydropower plants. The share of hydropower installed capacity in these rivers is about 77% of total hydropower installed capacity and 63% of total installed capacity in provincial power grid. These mainstream cascaded hydropower plants are characterized by large capacity, huge units, and dynamic operation control, etc. It will take a long time to be fully put into operation for all units. The hydropower plants with huge capacity have a significant impact on the long-term operation of large-scale hydropower systems and provincial power grids. In this paper, long-term scheduling methods for large-scale hydropower systems are presented and tested for dynamic operation control of Jinshajiang River and Lancangjiang River in Yunnan Power Grid (YNPG). It mainly consists of a unified evaluation method for all reservoirs to determine natural runoff process with same probability and a long-term scheduling method for large-scale hydrothermal system with different total installed capacity in different years. The method has been applied in long-term hydropower simulation scheduling analysis in YNPG from 2012 to 2015. The results show that the proposed methods can solve long-term scheduling for large-scale hydropower system. The proposed methods and ideas can provide a reference for large-scale hydropower system operations.

International experiences have been promoted to better prepare students for the global and rapidly changing society in which we live, to help them realize the impacts of engineering solutions, and to help them develop a deeper empathy for their project stakeholders, often those living in developing countries. If the international experience incorporates serving others through a project of need, it is commonly believed that the students learn on a much deeper level than through the conventional learning approach of classroom lectures, homework problems, and tests. At Michigan Technological University, international community engagement (ICE) programs founded in engineering include an international senior (capstone) design program, a student chapter of Engineers Without Borders-USA, two Peace Corps Master's International programs, community-based participatory research programs, several social enterprises, an international sustainable development certificate, and many supportive classes. More than 500 students have participated in one or more of these programs in the last 15 years, and the vast majority of those surveyed have reported greater satisfaction with their education and a deeper learning experience compared to traditional on-campus learning. A more rigorous assessment program has more recently been adopted, permitting the examination of institutional, program, and student learning outcomes, among others.

It has been suggested that the absence of residual protection against recontamination is a potential weakness of ceramic pot filters (CPFs). As a result, and against CPF manufacturers' recommendations, users may routinely apply bleach to CPFs as a way to prevent recontamination. Concerns regarding the potential repercussions on the CPFs' ability to disinfect water and/or their lifespan due to an interaction between chlorine and silver, as well as the health risks associated with chlorine poisoning and chlorination disinfection by-products (DBPs) exist. This preliminary study evaluated the effects of chlorination on silver-coated CPFs, manufactured and used in Guatemala, in terms of disinfection effectiveness and performance. Three scenarios including no chlorine dosing and high and low frequency chlorine dosing were used during the laboratory and field experimentation phases. Additionally, an assessment of CPF users' application of bleach was performed by interviewing rural families in Guatemala. The limited laboratory and field experimentation showed that the disinfection effectiveness of silver-coated CPFs will not be affected by bleach application to the untreated water. CPFs used during both phases of this study remained effective in removing bacteria at logarithmic reduction values (LRVs) ranging from 0.3 to 2.6 for E. coli and 0.7 to 3.0 for total coliforms. However, the lifespan of the CPFs might be negatively affected by this practice as there appears to be a relationship between bleach application, silver concentration, and flow rate performance. Additionally, high residual chlorine concentrations in the filtered water could potentially have adverse health effects on CPF users.

It is necessary to figure out the flood indicators and recognize the flood intensity clustering for understanding the flood from management perspective. In particular, flood events are indicated by their peak discharge, peak level, the maximum 24-hours volume, the maximum 72-hours volume, and the total flood volume. In this paper, to avoid the defects of single indicator in describing flood intensity, all these five indicators are calculated and their temporal variations are analyzed with the 53 year's flood records from 1955 to 2007 in Wujiang River. The fuzzy C-means algorithm (FCM) is used for flood intensity clustering to exhibit high internal (within-cluster) homogeneity of the flood and to detect the similar groups among observed floods. Trend analysis for the yearly maximum flood events from 1955 to 2007 shows that the peak flood discharge, total flood volume, and the maximum 72-hours volume have a continuous weak increase tendency that is marginally statistically significant. The flood peak level does not show a statistically significant trend at the 95% significant level. The maximum 24-hours volume exhibits an increasing trend at the 90% significant level. The clustering results show that the number of floods type I and type II varies from the 1950s to the 21st century and exhibits an overall increase trend. The chances of encountering floods type I and type II is greater than encountering flood type III. Floods are found to be getting more serious in Wujiang River after the 1990s.

With the rapid development of hydropower in China during the last two decades, inter-basin and large-scale hydropower systems have appeared. A variety of methods and techniques are needed to deal with these systems of complex scheduling relations. Therefore, it is vital to construct a decision-support system that is scientific, efficient, convenient, and available. A spatio-temporal resolution is presented to solve the optimal operation problem of complex inter-basin hydropower systems by analyzing existing optimal operation technologies and using computer science and artificial intelligence. The resolution includes directed-graph technology to describe the topology of cascade hydropower stations, smart memory and script control technology to set the restrictions automatically, interface programming, and the same model in MVC to handle the linkage between table and chart in multi-reservoir operation. By adopting these technologies, the mid-long term runoff prediction system, long-term, mid-term, and short-term optimal operation system and real-time operation system have been developed and applied successfully in provincial power grids of Fujian, Yunnan, and Guizhou of China.

A long-term optimal operation model for peak load regulating of typical days by hydropower systems is proposed. A successive load shaving algorithm is used for daily power scheduling of hydropower plants. The long-term operation and typical daily loads scheduling is integrated into one model by taking the minimization of the maximum residual load of typical days as objective. Aggregated function is used to objective transformation, and the model is solved by a successive searching algorithm. Case study shows that the proposed model can describe the long-term peak load regulating demands and yield better results than the models in which only the average power load are considered. The long-term operation plan and power schedule of typical days can be obtained synchronously. The proposed model is applicable for long-term hydropower operation in hydrothermal scheduling environment.

With the rapid increase of number and capacity of hydropower plants operated by single dispatching departments in China, more attention should focus on seeking more robust methods for reducing dimension curse, improving effectiveness and practicability of optimization results, and enhancing computational efficiency of large-scale complex hydropower system operations. In this paper, a general solution framework for large-scale complex hydropower system operations is presented from the real hydropower systems in China. The framework consists of intelligent strategies to reduce problem size during modeling, integrated optimization methods and search methods to vanquish dimensionality difficulties effectively and cope with complicated spatial-temporal constraints, as well as interactive interfaces to adjust optimal results. Two case studies are presented.

The water, sanitation, and hygiene situation in the community of Independencia, Peru is examined as a benchmark of progress toward the accomplishment of UN development goals. The objectives of this work are to assess the water supply and sanitation practices, model the existing water distribution system, and make recommendations for future expansion of the distribution system to provide a recommended level of service. Results of a community survey reveal that water use is currently half of that recommended, and in spite of water treatment and a high rate of sanitary water handling practices, water quality testing reveals that the water intended for consumption in the houses surveyed is below standards. It is found by hydraulic modeling of the existing drinking water distribution system that to provide a continuous supply of 50 liters per person per day, the diameter of the main water line would need to be increased, and sections may need to be lowered in elevation. Water system improvements could reduce the morbidity and mortality from diarrheal diseases by maintaining continuous pressure in the distribution system to prevent infiltration of contaminated groundwater, as well as by decreasing the recontamination of the water due to transport and household storage. Hydraulic modeling is helpful, therefore, in evaluating and improving water distribution systems in developing countries to attain development goals.

Transfer canals convey the water from source to destination for further use downstream. Canal runs in partial or complete cutting, filling or combination of both when the natural slope and canal slope are not same. If the canal runs only in excavation it leads to construction-related problems. Similarly if the canal is in-filling then huge quantity of borrow earth is required from borrow area near the canal. To eliminate these practical problems this paper presents the analytical solution of the balancing depths for canal section as well as canal length. The optimal cutting and filling depth is calculated from the earth-balancing section as well as for the whole length of those canals other than contour canals. For this analysis the parabolic section is considered for a given flow. The solution will eliminate the practical problem of dumping of huge quantity of earth generated from canal construction or borrowing a huge quantity of earth for canal construction.

Water bodies are often surrounded by plants and trees. Presence of these around the water bodies may influence the flow field and thus the evaporation from water body. To understand the role of these obstructions or roughness elements, an experimental investigation was carried out for evaporation rates of water under forced convective air flow in a wind tunnel. The effect of obstruction in the form of creation of additional turbulence caused by artificial roughness of small height on the evaporation rates and hence on the convective mass transfer coefficient has been investigated under varying conditions of air velocities and vapor pressure differential for circular pan of 0.93 m diameter fitted at the bottom of the test section. The respective ranges of flow velocity and pan water temperature for this study were 4 m/s to 18 m/s and 30° C to 50° C, respectively, at relative roughness height of 0.011. It has been found that there is a significant effect of the presence of roughness elements and this effect is a strong function of flow velocity and the vapor pressure differential.

In this paper, the adaptive-network-based fuzzy inference system (ANFIS) is adopted to forecast the freeze up water temperature of the Yellow River, which is the foundation for ice condition forecast. With its hybrid learning scheme, ANFIS is convenient for modelling the nonlinear multivariable process, for instance, in the case of modelling the hydrological information variety. Through analysing the limited hydrological field data, which is collected from the hydrometric stations in Inner Mongolia reach of the Yellow River, the forecast factors are determined as the model inputs. The related member functions and the predicted period are set up according to determination coefficient of forecast results. And the forecast results of water temperature are compared with the measured records in Shizuishan Hydrometric Station. Through such comparisons, it is discovered that the water temperature forecast results approximately agree with those of the field records. The ANFIS model is acceptable for simulating the freeze up water temperature forecast process and satisfactory results have been obtained.

Channel pattern and habitat features in a 32-km stretch of the West Branch of the Susquehanna River in north-central Pennsylvania were mapped to characterize existing features and to assess the geomorphic history of the river. River bed features on the horizontal scale of five meters or greater were mapped using a high resolution 455 kHz Lowrance StructureScan side-scan sonar imager and 83kHz HDS-10 Gen2 depth finder, as well as a Sontek River Surveyor ADCP and DGPS unit to collect more than 100,000 depth/location readings. The river was longitudinally traversed in a zig-zag fashion with an average cross-sectional spacing of 40 m. The data readings were processed using ArcGIS to produce both sonar image maps (SIMs) and digital bathymetry maps (DBMs) by contouring and gridding the sonar readings and combining them with one-meter terrestrial LiDAR data of the adjacent floodplain areas. The DBMs revealed a variety of bedforms in the channel that are interpreted as larger glacial outwash bedforms with smaller-scale modern flood bedforms superimposed upon them. Bedrock exposed on the channel bed were mapped and surveyed with respect to mid-channel islands. At various locations along the transect, pebble counts were made to characterize the size and nature of the riverbed sediments. Upstream of the Great Bend at Muncy, PA, the suspected location of a Pleistocene glacial ice dam, a five-meter deep channel is incised into the bedrock. The channel morphology data were used with hydraulic modeling to analyze the ability of a range of discharges to move the channel bed sediment and to hypothesize glacial dam-break events that may have shaped the current features of the West Branch of the Susquehanna River in north-central Pennsylvania.

Regionalization approaches are widely used in hydrology to identify homogeneous groups (regions) of watersheds to facilitate prediction of hydro-meteorological extreme events in ungauged basins for various applications. This paper evaluates statistical homogeneity of watersheds in each of the regions of Ohio that were delineated in the past studies (Koltun, 2003; Koltun and Roberts, 1990) to arrive at regression relationships for estimating flood-peak discharges at rural and unregulated streams. Results based on L-moment homogeneity tests indicated that all the Ohio regions are heterogeneous. Consequently a new set of homogeneous regions are proposed in Ohio based on conventional and global fuzzy cluster analysis procedures. Regional growth curves are developed for each of the newly formed regions and it is shown that their use results in effective quantile estimates at ungauged sites in watersheds of Ohio when compared with those resulting from the use of regression relationships that are being used for quantile estimation by United States Geological Survey (USGS).

Stochasticity in urban water demand arises due to the unpredictability and randomness of consumer behavior, which is influenced by population growth, climatic conditions, and conservation programs. Most urban water demand estimation methodologies are based on end-use models or stochastic models. End-use models describe the uses of water by households at the appliance level and require extensive and detailed data about water activities and water appliances. Stochastic models, however, predict water use using empirical relationships based on predictors, such as population size and water pricing. Integration of mechanistic end-use modeling with stochastic modeling can aid in better understanding of consumers' water use behavior and, therefore, can aid in better estimation of water availability in planning and management of urban water resources. A novel mechanistic-stochastic water demand model is developed here through the integration of an end-use model and a stochastic model. The model is developed using residential customer billing records from two water utilities. The historical water billing records are fitted to a gamma distribution based on the Akaike Information Criterion (AIC) values compared to exponential, extreme value, and log-normal distribution. Consumers are categorized into different groups from the distribution of water billing records and aggregated demand is estimated for the water system. To validate the modeled customer categories, housing survey data is collected and analyzed. Integration of mechanistic and stochastic modeling along with linkage of multiple data sources through this methodology can provide a powerful tool for efficient and sustainable water resources management.

Building on a recently found association of orbital forcings of the Earth and Moon with hydrological conditions on Earth, as inferred from the analysis of long-term precipitation data in California, this paper attempts to show the causes and predictability of El Niño/La Niña events. Temporal and spatial orbital oscillations of the Earth and Moon for the 1951 to 2012 period are characterized using the Moon and Earth's orbital geometries, which are based on proxy records obtained from the National Aeronautic and Space Administration (NASA.) The El Niño/La Niña Southern Oscillation Index (Niño 3.4) for the same historical period is analyzed in relation to the observed orbital oscillations of the Earth and Moon. The analysis shows evident association between these oscillations and Niño 3.4 index. This paper presents the results of this analysis and points to further validation studies using real-time data in the coming years. It also attempts to indicate the various potential applications of this novel association.

Water reuse introduces new interconnections among urban water infrastructure services. For both decentralized and centralized systems, water recycling influences the burden on the stormwater, wastewater, and drinking water systems. Reductions in drinking water demands, caused by an uptake in water reuse, can cause changes in system pressures and new hydraulic conditions in the network. The proposed research will explore the interconnections among urban water infrastructure for water reuse strategies and develop a new agent-based modeling framework to simulate the interactions among consumer behaviors, water reuse technologies, and existing water supply infrastructure. An agent-based model of consumers will be coupled with water infrastructure systems models, and both the water distribution system and water reclamation system infrastructure will be simulated using EPANET. Each agent, representing a household, will be associated with a node in the drinking water system where its demand is exerted. As agents adopt reclaimed water, demand inputs to the drinking water model and reclamation system model are updated accordingly. The framework will be used to simulate the emergence of the adoption of water reclamation and infrastructure performance based on metrics, including extreme pressures, changes in flows, and utilization of existing capacity.

The size and complexity of water resources networks typically require a large number of computationally intensive simulations to test effects of changes in network structure or management. Current tools can only visualize the effects of a few changes. Here, we introduce a new method and tool that uses parallel coordinates to simultaneously visualize large water resources networks and identify nodes that are (1) vulnerable (their connectivity depends on the existence of particular nodes); (2) topologically significant (when removed or added to the network, they cause other nodes to be vulnerable); and (3) redundant. We apply the tool to the 56-node lower Bear River water system that stretches from southern Idaho to the Great Salt Lake, Utah. Nodes that are connected to only one other node are the most vulnerable, including Great Salt Lake, Malad River, and Evaporation from Hyrum Reservoir. The three most topologically significant nodes are Cutler and the two junctions connecting the South Cache Valley and the Weber branches to the rest of the network. There are five highly redundant node pairs with more than 96% of the same connections including the Cache Valley Irrigation and Cache Valley New Municipal and Industrial service areas. This redundancy suggests that Cache Valley Irrigation is a promising source to transfer water from agriculture to urban use. The New Box Elder County Irrigation and South Cache Irrigation service areas have very low topological significance ranks and suggest that these irrigation areas may also be promising sources of water transfers. Our tool can also suggest candidate locations for dam removal (reservoirs with low topological significance or high redundancy); areas most benefiting from conservation measures (vulnerable nodes); and locations for monitoring (vulnerable nodes). Future work with this tool should incorporate flow direction and magnitude. The results of our tool can direct detailed simulation studies and sensitivity analysis. The tool scales to very large networks and identifies the most promising nodes to subsequently focus computationally-intensive simulation and sensitivity analysis efforts.

Real-world engineering problems typically involve multiple objectives that should be addressed simultaneously. A set of Pareto-optimal solutions that represents the trade-off among conflicting objectives can be identified to provide knowledge about the performance of alternative solutions for design and management problems. Many multi-objective evolutionary algorithms (MOEA) have been developed and designed to efficiently identify a set of nondominated solutions, and these algorithms have been successfully applied for realistic engineering problems. Realistic design problems may require more analysis and solution generation capabilities than provided by a typical MOEA. The fitness landscapes for realistic design problems are often nonlinear, complex, and multi-modal, and, in addition, water resources planning and management problems typically involve a diverse set of stakeholders with a set of preferences that are not represented mathematically and included in an optimization model. Identification of alternative sets of nondominated solutions that are similarly Pareto-optimal can address the problem of multi-modality in the decision space and provide additional insight to problem solution and options for implementation. The Multi-objective Niching Co-evolutionary Algorithm (MNCA) was designed to use a multi-population optimization search to evolve multiple nondominated solution sets. MNCA is demonstrated here for solution of two illustrative water resources management problems, including a water supply network design problem and a water quality management problem. Results are analyzed to demonstrate the use of MNCA to generate new insight and options for addressing difficult problems.

The use of optimization techniques to identify socially optimal solutions to allocation problems is widely accepted in the water resources literature. For cases with multiple criteria and multiple decision makers (MC-MDM), techniques traditionally lump the decision makers (DM) into a single user and evaluate the criteria, thus not capturing the influence of power dynamics that occur among DMs. Through application of stability methods such as the power index, an alternative method for solving allocation problems, one can assess whether a decision rule is likely to be accepted based on the parties' relative power. This work presents a method for applying the power index to MCMDM problems to determine the most stable decision rule. Because stability is concerned with minimizing the dissatisfaction of the most powerful party, stability can produce different outcomes from the conventional system-level optimization. This work presents this comparative analysis through a case study of the Caspian Sea resource allocation negotiation between five littoral states (Iran, Russia, Kazakhstan, Turkmenistan, and Azerbaijan). Goal programming, compromise programming, and power index methods are employed to evaluate the best scheme for allocation of the Caspian Sea resources. Results show that optimal solutions, analyzed by social planner methods, may not be stable in practice, as certain parties may be too dissatisfied with their allocation to enter into an agreement. This finding has important policy implications as it justifies why stakeholders may not accept the socially optimal solution in practice and underlies the necessity of considering solution stability in social planning and decision making.

Brazil currently has more than one hundred medium and large hydropower plants that, together with small hydropower plants, produce on average 91% of the total electricity in the country. To use most of the hydropower potential of a basin, hydropower plants are built normally in cascade. In some cases, the reservoir operation can cause elevation of tailrace water level from upstream plants, the backwater effect. Is this case, the original water level-discharge relationship isn't valid, but depends also on the downstream reservoir level. In the future, this effect tends to be even more intense and frequent as new hydropower plants and reservoirs are built. This paper presents a study of the backwater effect on the productivity of upstream plants and evaluates where and how much it represents in the Brazilian hydropower system. We analyzed the system with 143 reservoirs and three different hydrological scenarios with planning horizons of five years, corresponding to periods of dry, wet, and medium inflows in historical series. The backwater effect was significant, resulting in reduced generation by approximately 400 MW, or 0.6% to 0.8% of the total hydropower production. This results in up to 8% more thermal dispatch in the country. Furthermore, the effect is concentrated in a small number of large hydropower plants. Some suggestions are made to incorporate this effect in reservoir operation models for hydropower generation.

Texas faced the worst single-year drought in its history in 2011, and the battle against dry conditions brought on by that record-setting drought continues in many parts of the state, especially in those areas where water supplies have simply disappeared. Although rains have provided relief to some of the state, Texans are taking steps to have water available for future needs and to fast-track water supply projects desperately needed now. This paper features case studies of Texas cities and water suppliers who are responding to existing drought conditions and who are planning for potential droughts in the future. Response measures include water conservation, drought measures (including rationing in some cases), priority water right calls to protect senior water rights, fast-tracked implementation of new water supplies, water reuse, and close monitoring of the status of raw water systems using models and decision support tools.

The U.S. EPA and the Water Research Foundation have identified as a major research need the development of a standardized methodology to classify commercial, industrial, and institutional (CII) water users. Schemes to classify CII customers differ greatly and often lack adequate disaggregation, making evaluations of CII water use across sectors difficult. The primary challenge in evaluating CII water use and classifying its customers is that water use patterns vary widely because of the diversity within the CII sectors such as retail stores, which range from small convenience stores to regional shopping malls. This large water use variability is driven by differences in water use processes and technologies, varying employee and visitor occupancy patterns, and seasonal effects driven by fluctuations in populations and climatic factors. To overcome these complex challenges, this methodology proposes the use of utility water billing data spatially linked to property appraiser data to arrive at a detailed understanding of how CII customers use water. To arrive at a standardized approach that can be applied across the United States, this methodology uses clustering techniques to arrive at homogeneous CII categories. For this analysis, actual billing and property appraiser data for nearly 7,000 CII customers from Florida and Texas will be used. This will provide a large enough sample by which to cluster on the intensity of water use (liters per square meter of building area per day) and property appraiser attributes such a land use classification and heated building area. A standardized classification methodology to separate CII into homogeneous groups would allow a utility to better evaluate its CII sectors for water conservation, as well as project future water demands with greater certainty.

Recent major hurricanes have had a profound impact on U.S. coastal areas. The U.S. Army Corps of Engineers (USACE) has initiated an effort to develop a planning tool to support risk-informed decision making for planning hurricane protection systems (HPS). An HPS is a complex combination of constructed and natural elements, including levees, floodwalls, channels, pumps, gates, and wetlands. A life cycle approach in which the performance of an HPS over 50 or more years is examined is necessary to capture the influence of long-term phenomena such as climate change, and a probabilistic model is needed to represent the manifold uncertainties that exist in terms of climatologic driving forces and system responses. The modeling framework, event-driven Monte Carlo simulation, is designed to support accelerated planning efforts consistent with the USACE "Smart Planning" initiative. The Corps planning environment, model development framework, architecture, status, and issues are described.

The U.S. Army Corps of Engineers performs cost-benefit analyses to determine the economic efficiency of alternative flood hazard reduction plans. Calculation of damage to infrastructure is important in assessing the merits of a particular plan. Floods can damage roads directly, and there are indirect costs associated with travel delays and rerouting until damaged roads are restored to operating capacity. Through an expert elicitation, overtopping of road embankments in floods was identified as the major cause of physical damage to roads. An analytical computer model giving road damage based on flood hydrographs, originally developed for the Federal Highway Administration, is being updated for use by the Corps in an overall planning framework to estimate flood-associated damage. The model, after review, will be freely available for use. The model and planning framework are described.

This paper describes the analytical approach developed by the California Department of Water Resources (DWR) to evaluate the performance of alternative regional resource management strategies in meeting future water management objectives as part of the 2013 Update of the California Water Plan. The California Water Plan, mandated by state law and updated every five years, is used to guide regional and statewide water policy decisions. An overview is provided of the Plan of Study DWR developed through a rigorous public outreach process to look out to the year 2050 to define multiple plausible future scenarios that consider how future population growth, development patterns, a changing climate, and other uncertainties interact to affect water management. The Water Plan has identified 30 resource management strategies that California's regions can invest in to help reduce water demand, improve operational efficiency and water transfers, increase water supply, improve flood management, improve water quality, and practice resource stewardship. The evaluation of these strategies in Update 2013 will provide decision support and guidance to California's regions and the State legislature about promising investments to improve water management in California.

Annual maximum flood risk is commonly assessed under the assumption of stationarity, i.e., flood risk is unaffected by trends, periodicity, climatic variables, and anthropogenic activities. In light of recent findings, however, this assumption should be reconsidered. Analyses of the nonstationary character of flood series induced by natural climatic variation, climate change, and/or anthropogenic activities are essential to develop more appropriate statistical models for flood risk assessment. This study aimed to investigate nonstationarity in annual maximum flood series for moderately impaired sites in the Eastern United States. Linear trends in flood series were identified for almost 30% of the investigated sites. A larger number of sites exhibited a change point implying a shift in the mean annual maximum flood magnitude. A high degree of correlation was observed between flood magnitude and associated precipitation series; however, no significant influence of temperature on flood magnitude was detected. Investigation of teleconnections between flood series and climatic indices revealed significant relationships with the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) for sites located in Indiana, Ohio, Kentucky, and the New England region; few sites exhibited significant correlation with the Multivariate ENSO Index (MEI). Efforts were also made to distinguish the effects of anthropogenic activities on flood response from the influence of natural climatic variation.

This paper presents a study on the temporal correlation between the hydrological regime and the behavior of winds in the main regions of Brazil. Currently, the wind power participation in Brazilian energy is still relatively very small, with 1.3% of the total installed capacity of the system. The operation planning of the power system uses a deterministic forecast of wind power production based on expected average values and only the stochasticity of the inflows are considered. In a relatively near future, participation of wind generation in the country will tend to be much more significant. The impacts of winds seasonality in the operation of the electrical system can be addressed by generating scenarios that preserve the spatial and temporal correlation between the sources that might be applied to improve existing models for planning system operation such as HIDROTERM, SolverSIN, and NEWAVE. The proposed methodology studies the energy complementarity between wind and hydro sources, measuring the intensity of seasonal and annual correlation in the major country subsystems. The scenarios can be obtained through autoregressive multivariate models applied to the time series of wind and inflows of the major subsystems of the country. The product of this work is intended to provide input data considering wind stochasticity into decision support systems used for planning the operation of the Brazilian National Interconnected Power System.

As I examined the water forecasting done by the consultants to the various water management agencies - the US Army Corps of Engineers, the South Florida Water Management District (SFWMD), the Miami-Dade Water and Sewer Department (WASD)—I became increasingly alarmed.Would there be enough water for the sprawling cities on the east and west coast surrounding the Everglades and for the vast and intensive sugarcane, cattle, and citrus plantations upstream to the north of the Everglades?Would there be any water left for the Everglades itself? The water forecasting method used by the Army Corps of Engineers, or more accurately, by their consultant, simply applied the IWR-MAIN model is a simplistic manner, biasing the forecasts downward, and consistently underestimating the population growth and the water use per capita on the residential side.On the municipal and commercial (M&I) side, the water coefficients were also borrowed from "other cities," with certainly different climates and industrial mixes. No effort had been made to "naturalize" or customize the forecast coefficients to South Florida.

This work presents a methodology to simplify the nonlinearities involved in reservoir operation that may contribute to the development of simulation and, particularly, optimization models applied to energy generation and multiple uses of the water in complex reservoir systems. The nonlinearities studied include water level, area and storage relations in the reservoirs, as well as evaporation. The proposed methodology uses linear and polynomial regression to simplify the level-area-storage curves, often represented by fourth degree polynomials. For evaporation, the calculation proposed is based on the history of monthly averages storages and corresponding areas before the optimization process, eliminating the need of calculating the area that represents a nonlinear constraint in the optimization problems. The methodology was added in HIDROTERM, a nonlinear programming model applied to optimize the management and operation of the Brazilian hydrothermal system, a linked network with 143 reservoirs in which 68 are run-of-river and 75 have storage to regulate flows. Using a very conservative setting, without compromising accuracy in results, all reservoirs had level-area-storage curves simplified to first or second degree polynomials. For evaporation, only two reservoirs had a difference in the standard deviation greater than 0.5% of the long term average inflow from the estimated value to the calculated one. The processing time was reduced on average by 52%. This reduction is very welcome given that a new stochastic version of the model is currently under development, originally deterministic, with a large increase in the problem's dimensions.

The developed world has been forged on the supply side. In the past, we've assumed that we could engineer our way out of trouble. However, "when we build big, we build wrong." This is because we typically build within a narrow band of expected environmental and financial conditions. Those assumptions, spurred by the relative passivity of the Holocene epoch, are being proven to be invalid for the future. Solving the water and financial volatility issues rapidly and effectively with Smart Grid installations will be a key hallmark of sustainable cities and will provide a unique competitive advantage for those cities in other jurisdictions.

Global changes facing the Corps of Engineers include increasing water demand and the potential for increases in drought conditions. A major effort took place in the early 1990s to develop drought contingency plans (DCP) at all Corps projects having controlled reservoir storage. The changes that have occurred over the intervening 30 years, especially changes in demographics driving water demand, make it imperative that the Corps update its DCP to support sustainable water management. The Global Change Sustainability (GCS) Program was tasked with updating these vital DCP to account for global and climate change. As part of this effort, WEST Consultants reviewed more than 100 DCP covering more than 250 projects from every Corps district throughout the nation. This paper details the water law issues governing distribution of the resource, such as riparian and prior appropriation, along with agreements concerning water usage among the states. Additionally, the water supply agreements at the projects are detailed along with a discussion of the surplus water available at the projects during a drought. This paper provides a comprehensive overview of the variability in water law and water supply between Corps projects throughout the nation.

The Interagency Advisory Committee on Water Data is finalizing proposed updates to the current national flood frequency guidelines, known as Bulletin 17B. Among the updates is a new multiple Grubbs-Beck test (MGBT) for low outliers. It is a generalization of the Grubbs-Beck (GB) test recommended in Bulletin 17B. Bulletin 17B defines low outliers as unusually small observations "which depart significantly from the trend in the rest of the data." Such unusually small values might better be labeled as Potentially Influential Low Flows (PILFs). PILFs can have a large influence on estimates of extreme flood quantiles; that is an undesirable situation if flood frequency procedures are to be robust. This paper reports on Monte Carlo analyses of the performance of low-outlier/PILF tests, including the Bulletin 17B GB test and variations of a MGBT. It also considers the accuracy of log-space method-of-moments flood quantile estimators that use different PILF identification procedures.

Almost 90% of the electrical energy in Brazil is produced by hydropower plants, but to cover national demand and to ensure production during dry periods the system operates in conjunction with a set of thermal power plants. The Brazilian hydrothermal system is completely linked together and the main purpose of operation is to minimize the cost of energy production considering a long-term horizon, generally five years. Therefore the complexity of the planning operation involves a large set of variables and many decisions have to be made to ensure maximum efficiency. Today the Brazilian National System Operator (ONS) runs a set of models to define the dispatch and the marginal cost of the energy in different parts of the country in a weekly time step. These models are very complex and are not practical to support basic information for the electrical agents in a short time. For this reason a very practical decision support system called SolverSIN was developed. This paper describes the SolverSIN model and shows its performance in dealing with a very complex hydrothermal systems analysis. The model was prepared to run with the Brazilian system considering its equivalent energy reservoirs scheme but its methodology can be adapted for any system. The main variables of the planning operation are estimated in a very short time, and different situations can be explored to conduct sensitivity analysis of the main ones. Another important SolverSIN characteristic is its ability to run different hydrological scenarios to evaluate the impacts on dispatches and energy costs. This is very important considering that the greater the safe thermal energy production of the system, the lower the electrical costs and the greater the protection to the environment due to minimization of oil consumption.

Using recently uncovered association of analogous orbital forcings of the Earth and Moon with similar hydrological conditions on earth, water year 2012 was predicted to be a drought year in California. The prediction followed a previous work that analyzed precipitation data of 1976 and 1994, which were one Saros cycle of about 18 years apart, and reviewed water year 2012's projected orbital pathways of the Earth and Moon, which were obtained from the National Aeronautics and Space Administration (NASA). According to the California Department of Water Resources' water year type classification of Wet, Above Normal, Below Normal, Dry, and Critically Dry water year types, both 1976 and 1994 were Critically Dry years in both the Sacramento and San Joaquin Valleys of California. Water year 2012 precipitation data at a cross-section of stations throughout the state as well as estimated natural flows of eight major rivers in California showed dry hydrological conditions. This paper presents the results of the analyses of correlations between statewide precipitation data of 1976, 1994, and 2012 and illustrates a successful validation of the previously projected drought condition in California. The result is the first successful validation of the utility of this novel finding that may help us for a longer-range prediction of hydrological conditions on earth. The paper points to the need for continued validation studies globally in the coming years and the utility of the finding for sustainable water resources engineering and other applications.

Based on a recent finding of the predictability of El Niño/La Niña events (see accompanying paper), water year 2013 (October 1, 2012, to September 30, 2013) was expected to be a weak El Niño/La Niña year. In light of this finding, this paper revisits the definitions of El Niño/La Niña events, provides a new perspective to these events as a single natural phenomenon that is characterized by predictable oscillations of the Earth and Moon's orbital forcings, and presents the validation results of predicted weak El Niño/La Niña event during the current water year of 2013. The association of analogous oscillatory orbital forcings of the Earth and Moon and Niño 3.4 index is shown using available real-time data during the current water year. Potential applications of the validity of this association are also discussed.

To support ongoing watershed protection and planning efforts, the Ventura County Watershed Protection District (VCWPD) recently completed a watershed management plan report for the Ventura River Basin. VCWPD has also developed the Integrated Watershed Protection Plan (IWPP) as the culmination of a series of long-range planning efforts. The objectives of the IWPP include the provision of a systematic process for the inclusion of projects into the VCWPD's Capital Improvement Program (CIP) and improving the long-range planning process. The IWPP process achieves these objectives by gathering information about existing flooding, operations and maintenance (O&M) practices, drainage facility deficiencies, access, and environmental concerns in the VCWPD's jurisdictional areas. From this information, a prioritized project list is developed for inclusion in the CIP. Projects are proposed to address identified issues and are ranked relative to each other using a scoring matrix. The highest priority projects are then the subject of further study using a multistep planning and evaluation, predesign, and final design process if the recommended project is found to be cost effective and environmentally viable. Most of the Ventura River watershed is undeveloped open space, with more than 75 percent of the watershed classified as rangeland and forest. Development is focused in lower portions of the basin along the Ventura River and tributary streams in the relatively flat areas, including floodplains, and the Ojai Valley. The limited extent of existing and new developments results in limited revenue for flood management improvements in the Ventura River watershed. Because traditional structural measures such as levees are very costly, VCWPD also works to identify and implement other flood management practices that can reduce hazards in flood-prone areas. It is also important to note that some areas in the Ventura River watershed subject to flooding are located on alluvial fans. For example, in the San Antonio Creek Watershed, floods in alluvial fans are highly unpredictable, and the VCWPD cannot provide cost-effective structural improvements in this watershed. In these areas, individual property owners need to be proactive to identify flood hazards and implement measures to reduce flood hazard risks. This paper will discuss watershed management and related efforts conducted in this watershed in the past few years to improve water supply, enhance habitat, and reduce flood risk.

The importance of inter-basin water transfer project is its ability to balance the nonuniform temporal and spatial distribution of water resources and demands, especially in arid and semi-arid regions. A water transfer project can be executed if satisfied some economics and environment criteria. In this research, a methodology is proposed for inter-basin water allocation using virtual water concept. Thus, an optimization model with an economic objective function based on virtual water maximizes the benefit of the inter-basin water transfer. In various scenarios of allocating water, the productions of basins that receive transferred water and sending basins and related virtual water are estimated. The best scenario must have the maximum efficiency and benefit based on value of water and production. The effectiveness of this methodology is examined by applying it to a large-scale case study of interbasin water transfer from Solegan to Rafsanjan basin in Iran.

Deterministic and stochastic weighting methods are the most frequently used methods for estimating missing rainfall values at a gauge based on values recorded at all other available recording gauges. However, spatial interpolation methods used for estimation of missing precipitation data at a site seldom check for their ability to preserve site and regional statistics. Such statistics are primarily defined by spatial correlations and other site-to-site statistics in a region. Preservation of site and regional statistics represents a means of assessing the validity of missing precipitation estimates at a site. This study will evaluate the efficacy of a newly proposed Fuzzy-Logic interpolation method aimed at estimation of missing data with the objective of minimizing estimation error and preserving site and regional statistics. Rain gauge sites in the state of Kentucky, USA, are used as a case study for evaluation of Fuzzy-Logic method. Several error and performance measures will be used to evaluate the method and trade-offs in accuracy of estimation and preservation of site and regional statistics.

Landfill leachates are frequently discharged to publically owned treatment works (POTWs). The presence of UV quenching substances in leachate interferes with UV disinfection at the POTWs. Also, the biorefractory organic nitrogen contained in the leachate contributes to the plant's effluent nitrogen making it difficult to meet the tightening total nitrogen effluent regulations in some regions of the country. To study the changes in organic carbon and nitrogen with landfill age, leachate samples with landfilling ages ranging from two to 30 years from a large landfill in Kentucky were collected and fractionated on the basis of their particle size (molecular weight cut off) and hydrophobicity into humic acids (HA), fulvic acids (FA), and a hydrophilic (Hpi) fraction. The results identified the hydrophilic component, which was mostly < 1 kDa as the major source of the total organic carbon and organic nitrogen. This component tends to persist even in the older stabilized leachates whereas the HA fraction gets degraded or converted into FA fraction. The effectiveness of biological treatment for leachates at different ages was examined to develop an understanding that might help design on-site treatment methods. It was observed that on-site biological treatment was able to degrade organic matter measured as total organic carbon (TOC) but was not effective for removal of UV quenching substances, especially for the older leachates. This pointed to the possibility that the microorganisms with the capability to degrade the UV absorbing substances need a detention time of around 10-20 years, which cannot be provided by on-site biological treatment. It was also observed that one-third of the organic nitrogen was from proteins that were mainly concentrated in the Hpi fraction.

Crystalline titanium dioxide (TiO2) composed of mostly anatase was applied to remove fluoride from water by adsorption. A fluoride concentration of 1.15 mg/L, which is below the standard level of 1.5 mg/L was obtained within the equilibrium time of three hours from an initial fluoride solution of 5 mg/L. Greater fluoride uptake was observed at acidic pH than at alkaline pH of the solution. The removal of fluoride was not affected by sulfate and calcium in solution while bicarbonate had a negative effect on the removal of fluoride. Increasing the pH of the solution suppressed the removal of fluoride. Overall, TiO2 showed promising potential as an adsorbent for removal of fluoride from natural waters.

Many protective response actions are available to protect consumers affected by a water distribution contamination event. Routing a fleet of emergency vehicles to disseminate water warnings is considered in this study. Identifying optimal trips to effectively notice consumers is difficult as a water contamination event is a complex and dynamic system and vehicle routing problems are categorized as NP-hard domain. A novel framework is developed by coupling an agent-based model with an optimization algorithm to search for optimality in a warning dissemination. Solutions representing an optimal front are explored to demonstrate the relationship between the number of exposed consumers and the maximum travel time as conflicting objectives. NSGA-II is used with a tree-based representation. The developed framework is applied to a virtual case study, Mesopolis.