Building Partnerships

In the Fall of 1999, the Department of Civil and Environmental Engineering at the University of Pittsburgh underwent an accreditation visit using ABET Criteria 2000. Although the preparations were made for the whole program, aspects of the process that particularly relate to water resources engineering will be highlighted in this paper. ABET Criteria 2000 require that graduates of civil engineering programs must demonstrate proficiency in at least four areas of civil engineering. This requirement is unique to civil engineering programs and is the outgrowth of ASCE's recommendations. Our Department chose water resources as one of the four areas on which to focus its preparations. The development of program and course objectives, program outcomes and assessment methods will be examined. Concerns, weaknesses and deficiencies are terms which describe a program's degree of compliance with Criteria 2000. Because of a certificate program which the Department had instituted, a weakness was identified which required some modifications to the curriculum. Our approach to the process of resolving this difficulty will be discussed.

In these days of doing more with less, engineering educators have demands from accreditation authorities, state higher education offices, and even their own universities for comprehensive assessment systems of their degree programs. A good assessment program includes input and evaluation from each of the constituencies or "shareholders" of a degree program as to the achievement of the program objectives, and must generate results to improve the effectiveness of the program. This paper presents the assessment plan of an undergraduate civil engineering program at a small state-supported college. The plan was prepared to meet the requirements of both ABET-EAC and the Commonwealth of Virginia, and contains several innovative features.

American Water Institutions have played a major role in our quality of life as a Nation. We have lost our leadership in this field and the federal and academic roles have diminished. Inadequate attention is given to asset, regional and watershed management, as well as modernization of water law. The system is fragmented; wasteful of economic and professional resources. A number of solutions, as well as models which might serve us, are discussed.

Present paper summarizes experiences of authors in offering an online programming course in fall 1999 for engineering students at Virginia Tech. Results of student surveys indicated that the online version of course was not well received by the students. A number of honor violation cases were recorded. Use of listservs in online instructions is described. Analysis of homework submission data indicated that the online nature of course did not help in students' procrastination problems.

The Colorado River's 80-year history of treaties, compacts, laws, and court decisions are often referred to as the "Law of the River." The U.S. Bureau of Reclamation (USBR) has developed operating criteria to satisfy these legal requirements. Satisfaction of these complicated criteria is one important measure of the success of a basin model. USBR simulation models such as the Colorado River Simulation Study (CRSS) and the 24 Month Study have incorporated these criteria and are widely used for policy analysis. Both of these models have been reimplemented as rule-based simulations in RiverWare, a general river basin modelling tool. The application of optimization to policy analysis on the Colorado River has been limited by the ability of optimization models to similarly represent these mandated requirements for operations. Using the goal programming component of RiverWare, we have created a monthly optimization model of the Colorado River that replicated the 24 Month Study. Using this solution as a base, the hydropower value of selectively relaxing policies was found.

The client/server functionality of the global Internet makes it possible to design and develop sophisticated distributed databases. Until recently, however, implementing these systems has required extensive programming experience and expertise, as well as knowledge operating systems. New and considerably easier to use database applications development environments are now making it possible for engineering professionals having relatively little programming expertise to design, build and maintain sophisticated database systems to meet their specific needs. Several example applications will be presented to demonstrate the flexibility of these systems.

The Government Performance and Results Act requires that federal agencies measure their performance by comparing the dollars they spend to the good they do. The Corps of Engineers receives funding for nine different program areas, such as flood damage reduction, navigation, and the environment. To measure its environmental performance, the Corps must identify the ways in which it improves environmental quality, define metrics that best capture these contributions numerically, collect the appropriate data, determine how much money it took to produce the contributions, and then compare the contributions to the costs. For the US Army Corps of Engineers, this requires monitoring and managing their ecological resources and remediation efforts. This desire has highlighted the need for a web based tool that provides access to spatial environmental databases and supports the Corps in performing environmental evaluations. This tool assists the Corps with the management and monitoring of national environmental investments at various geographical levels (national, regional, state and watershed) for numerous environmental outputs and their corresponding financial inputs.

During development of the CALFED Bay-Delta Program's Water Transfer Program, it became apparent that the current mechanisms used in California to apply for permission to transfer water were inefficient and the flow of information throughout the public arena was very limited. These inefficiencies tend to cause delays in garnering state or federal approval and have created concerns of adverse impacts to third parties. Given the fact that many water transfers are proposed to resolve immediate or near-term water supply shortages, approval delays can be frustrating and costly for transferring parties and the approving agency. Limited public disclosure and information sharing regarding market processes and protections can further aggravate attempts to build a more robust water market. The CALFED Bay-Delta Program envisioned an on-line, expert system that would greatly assist water transfer proponents with applications, allow reviewing agencies to respond in a more timely fashion, and vastly improve the flow of information to all who are interested. This paper will provide insights into how the development of On Tap is proceeding and the timeframe for public release. On Tap will provide water transfer proponents with a complete picture of jurisdictional authorities, application requirements, and links to pertinent information. On Tap will also provide a searchable database and a variety of resources to assist with improved public understanding of the California water market and with the flow and disclosure of pertinent information.

The basic objective of the present study is to regionalize the area defined by the States of Illinois, Indiana and Ohio in the U.S. to homogeneous drought regions. The climate in these states is similar. Monthly Palmer's Drought Severity Index (PDSI), precipitation and temperature are used in the study. The principal component analysis is the basic tool used in the study. The classification of this area into homogeneous regions by using rotated and unrotated principal components is discussed. The results indicate that classification by rotated principal components is superior to that determined by using unrotated components.

Fairfax County Water Authority (FCWA), serving the Virginia suburbs of Washington, D.C., draws water from both the Potomac River and the Occoquan Reservoir. Deciding how much water to treat from the river versus the reservoirs is a multi-dimensional problem including variables such as historic reservoir inflows, time of year, historic and current Potomac flows, a regional operating agreement, current regional demands, and current reservoir storage. The challenge was to develop graphical tools that could easily and quickly be used by planners, water managers, and operators in both drought and normal years to maximize the reliability and use of the reservoir resource. The resulting graphical tools exploit the flexibility allowed by dual-supply systems, allowing personnel to choose an appropriate reservoir release rate given different reservoir storage levels and time of year. The curves helped guide release decisions during the drought of 1999, allowing managers to maximize reservoir water supply withdrawals while ensuring adequate reliability of reservoir refill and preserving emergency storage at appropriate reliabilities. Managers understood that the "cost" of fully utilizing the reservoirs during the drought was to incur a 1% chance that withdrawals would have to be reduced during the winter, when the free flowing Potomac is able to more than meet demands.

The Washington, D.C. metropolitan area is supplied by three major utilities serving a total population of 3.6 million people. Planning for drought in the Washington, D.C. metropolitan area has been conducted for decades. In addition to the structural alternatives studied, an academic exercise conducted largely at the Johns Hopkins University in collaboration with the Interstate Commission on the Potomac River Basin concluded that gains from coordinated use of existing water resources would meet demands projected for the region well into the 21^st century. The results of that essentially non-structural alternative were adopted as operating rules in 1982. Planning for drought has continued with the refinement and exercise of these regionally adopted rules for coordinated operations of the Potomac River and associated supply reservoirs. Water supply conditions during the summer of 1999 necessitated the first use of the full range of resource operations to meet municipal and environmental needs. Experiencing the real thing presented some unexpected challenges. Creative management strategies were required because the extremely low flow conditions in the river caused releases from upstream storage to take longer to get to the intakes than expected. And at times, they also exceeded demands because intermittent rains that fell unpredictably. Thus, the inefficiency of river regulation was encountered first hand. Recently completed variable yield analysis to assist the operation of the direct supply reservoirs was incorporated to quantify the risks involved in temporarily exceeding reliable yields. Briefings for an extraordinary number of hastily called meetings and responses to questions from all branches of the media consumed an unanticipated amount of time and resources; especially after mandatory restrictions were imposed in a jurisdiction served by only one of the regional utilities.

Reservoir operation could be divided into two parts; one is for a flood control during flood season and the other is for a water conservation during non-flood season. This study presents a methodology for the estimation of lower limit water level by the frequency analysis of dam inflow series, which can be used for the determination of the firm supply discharge in multi-purpose dams. The proposed methodology is applied to Soyang and Yongdam dams in Korea for the estimation of lower limit water levels from inflow-duration-frequency relationships. Also the operation of Soyang dam is evaluated by using the estimated lower limit water level. If the proposed methodology is used we may establish more efficient water resource planning for reservoir operation by considering some multi-objectives such as downstream water supply, hydropower generation, and maintaining reservoir water level during non-flood season.

The Butte City Bridge is located on Route 162 in Glenn County, California over Sacramento River. The bridge was originally constructed in 1948 as a replacement structure. Riverbank erosion was first noted at the bridge site in 1953, and has been continuing till present. The proposed project is to construct a series of rock spurs with sheet piles along the westerly bank of the Sacramento River in an effort to protect the Butte City Bridge from continued erosion of the upstream bank.

Study of the railroad bridges crossing the Wisconsin River at Sauk City, Wisconsin, indicates that increasing the width of the west bridge is the best way to improve flow conditions through the west bridge without adversely impacting the gravel/cobble bar immediately upstream of the west bridge. A two-dimensional model was used to design a rock guide dike just upstream of the new opening and determine where bank protection is needed after construction of the project. Flow direction information gathered from the two-dimensional model was used with HEC-RAS to perform the scour analysis.

The U.S. Army Corps of Engineers and City of Phoenix, Arizona are partners for an environmental restoration project along the Salt River referred to as the Phoenix Rio Salado Project. The project includes the construction of a low-flow channel along a five and one-half mile reach of the Salt River beginning at Interstate 10 and proceeding downstream to 19^th Avenue. The proposed low-flow channel is a trapezoidal channel with an average bottom width of 61 meters (200 ft). This low flow channel invert is 2.44 (8) to 3.66 meters (12 ft) lower than the existing Salt River channel invert. Located within this reach of the Salt River are five roadway bridges and two sand and gravel operation conveyor bridges. Since the channel invert is being lowered 2.44 (8) to 3.66 meters (12 ft), the project included an evaluation of all bridge crossings to determine if the structures were stable under proposed project conditions. Countermeasures were evaluated for those bridges determined to be unstable. Countermeasures evaluated included roller compacted concrete (RCC) bed armoring and grade control, and local scour bed armoring, and structural retrofit. This paper summarizes the results of the evaluation along with the recommended alternative.

A study was conducted to determine potential maximum scour depths for the foundations of the replacement east span of the San Francisco-Oakland Bay Bridge, as part of the ongoing structural design. This effort presented unique challenges as strong tidal currents, large depths, and cohesive bottom sediments characterize the site. The authors met these challenges with a multi-faceted approach to the problem. First, design current velocities were determined using a two-dimensional hydrodynamic model of San Francisco Bay in conjunction with ADCP hydrographic surveys. Analytical scour calculations were performed and live-bed flume tests of the proposed foundations were also conducted. Finally, two separate methodologies were used to interpret the physical model tests in order to calculate potential scour depths around the foundations.

A generalized inverse procedure is developed for model structure and parameter identification. The procedure seeks to minimize a weighted composite objective function measured in the parameter, observation, and prediction/management spaces. The new methodology unifies model structure complexity, model parameter identifiability, model prediction reliability, and data sufficiency. The utility of the new methodology is demonstrated by an application to a water resources management problem in Southern California.

This paper briefly describes nonlinear regression methods, a set of 14 guidelines for model calibration, how they are implemented in and supported by two public domain computer programs, and a demonstration and a test of the methods and guidelines.

The development of a regional ground-water flow model of the Death Valley region in the southwestern United States is discussed in the context of the fourteen guidelines of Hill. This application of the guidelines demonstrates how they may be used for model calibration and evaluation, and to direct further model development and data collection.

A procedure was developed to automatically calibrate a groundwater flow and heat transport model, resulting in the estimation of hydraulic conductivity and flux across the water table in wetland systems. This paper describes differences between previous approaches and this study, and summarizes some challenges in the method implementation The procedure was validated in a sequence of hypothetical models with known structure and parameters, and applied to a wetlands system located near Wilton, Wisconsin.

An overview of the annual hydroclimatology of the conterminous United States is provided. A unique dataset of time-series of monthly streamflow and climate is constructed which accounts for the complex variations in hydrology and climate at 1,337 watersheds in the U.S. New relationships between long-term precipitation P¯, potential evapotranspiration PĒ and actual evapotranspiration Ē are developed and compared with previous relations. Previous studies argue that the ratio Ē/P¯ is only a function of the aridity index PĒ/P¯. We show that by introducing soil water holding capacity, these relations can be dramatically improved. Our resulting relationships provide dramatic improvements over previous relations introduced by Turc, Pike, Oledkop, Schrieber, Budyko and others over the past century. We also describe the climate sensitivity of streamflow. We use a robust nonparametric estimation method to generate a contour map of the precipitation elasticity of streamflow for the continental U.S.

The aim of this paper is to assess the impacts of climate change on hydrological indicators such as surface runoff, potential and actual evapotranspiration. Two study areas, one in Central and one in Northern Greece are chosen in order to estimate the hydrological effect of climate change.

Annual precipitation for climate divisions in the Great Plains between the Rocky Mountains and the Mississippi River have been used to define the duration, amplitude and geographic extent of increased mean annual precipitation in the closing decades of the 20th century. Visual interpretation was used to group climate divisions into broad regions with similar patterns in the time series of filtered standardized annual precipitation. Four regions that included the majority of the Central and Southern Great Plains showed a significant increase in mean annual precipitation over the last two decades. For these regions the duration and amplitude of the increase is greater than for any other increase in the 20^th century. The peak amplitude of the increase corresponds to roughly 10% of the annual precipitation and about 50% of the inter-annual variability of annual precipitation. Cumulative distributions of the annual precipitation further showed that within the 10% and 90% cumulative range increased by a similar amount. However, the wettest years in both time periods remained comparable, while the driest years in the 1979–1998 period did show an increase over the 1895–1978 period. Thus, water deficits due to dry years have been less severe and less frequent over the last two decades. This study shows that the increase in annual precipitation over a large portion of the Central and Southern Great Plains and over the last two decades is significant in amplitude and duration compared to variations in annual precipitation during the early part of the 20^th century.

Wavelet analysis has been introduced during the past ten years in which a different type of basis functions, called Wavelets, are used. Wavelets are localized in time as well as in frequency. In the theory of Wavelet transforms, the notion of ‘frequency' is changed to an equivalent one of ‘scale', where large scales correspond to low frequencies and small scales correspond to high frequencies. By using Wavelet analysis, longer time windows can be used to detect low frequency (large scale) information, while shorter time windows can be used to detect high frequency (small scale) information. Wavelet analysis offers a different approach to investigating signals. In effect, by using the Wavelet transform the signal is decomposed into components of different scales. Wavelet analysis can be used as a tool for performing a wide range of tasks which include: detecting discontinuities in signals, detecting long-term evolution (trends), detecting self similarity (fractal signals), identifying pure frequencies (time-frequency analysis), suppression, and compression of signals. In this paper Wavelet analysis is used to investigate the trends in hydrologic time series. This new method of trend analysis appears to be quite robust and useful.

A two-dimensional mathematical model for calculating suspended sediment transport is presented in this paper. The transport equation for suspended sediment is solved using a hybrid finite-analytic technique. The description of bed boundary condition is accomplished using a recently developed entrainment function. The model is systematically tested against a series of analytical solutions, flume experiments and other related numerical results for different flow types and boundary conditions. The comparisons reveal that the model predictions are effective and reasonably accurate.

The CCHE1D model was designed simulate long-term channel morphologic changes in ungauged watershed systems. The model computed unsteady flows in channel networks of compound cross sections using the diffusion wave approximation, taking into account the effects of in-stream hydraulic structures, such as culverts, measuring flumes, drop structures, and bridge crossings. The model simulated sediment transport under the assumption of local equilibrium, as well as bank toe erosion and mass failure due to channel incision. In order to make the model applicable to a wider range of real-life problems, the flow model now solves the full St. Venant equations (dynamic wave approach), and the new sediment transport model adopts a non-equilibrium approach and a coupled procedure to calculate non-uniform sediment transport, bed changes and bed material sorting. The CCHE1D model now offers multiple options for sediment-related parameters such as sediment transport capacity, wash load size range, bed material porosity and mixing layer thickness. The CCHE1D model is highly integrated with landscape analysis tool TOPAZ and watershed models AGNPS 98 and SWAT, and is supplemented by a sophisticated graphical user interface that offers GIS capabilities including automatic definition of the drainage network based on elevation data, computational mesh generation, and database management. It has been tested in several experimental cases and applied to Goodwin Creek watershed.

A river modeling study was made for the Santa Ana River/Mentone Fan in San Bernardino County, California. The purpose of the study was to characterize the existing and future flooding regimes and sediment transport along an eight-mile length of the river and alluvial fan. A short distance upstream from the study area. Seven Oaks Dam has recently been constructed. In response to such a project, the river channel is expected to undergo changes thereby affecting the habitat and habitat renewal. Seven Oaks Dam will alter the storm flow of the Santa Ana River that is the primary source of flow for the study area. The reservoir will also detain nearly all the bed sediment supply to the study area. In order to quantify the boundaries of the 50- and 100-yr floodplains and the sediment processes under the natural and altered regime, a modeling study was made using the FLUVIAL-12 model. Short term changes were modeling using the 50- and 100-yr floods, respectively. Long-term changes, on the other hand, were modeled using a flood series representative of the long-term flood flow. The reductions in floodplain area for various cases were quantified.

Scour at bridges; over coastal waterways is caused by unsteady flows due to diurnal and semi-diurnal astronomical tides, storm surges (hurricanes, extratropical cyclones, and tsunamis), and combined riverine and tidal flows. Continuous rising: and failing, astronomical tides influence long-term trends of aggradation or degradation and produce some local scour around bridge piers and abutments. However, large amounts of contraction scour and severe local scour may be caused by storm surge that can exceed 23 ft (7 m) on the open coast. Storm surge can greatly increase water surface elevations and currents at coastal bridges, although durations of the increases are comparatively short, usually lasting no longer than several hours. Therefore, reliable estimates of water-level changes and currents under storm conditions are needed to account for roadway overtopping, hydrodynamic loads, and scour when planning and designing coastal bridges.

A Decision Support System (DSS) for optimal operation of multireservoir systems employs the powerful graphical user interface for the MODSIM river basin network flow model in creating applications for the CSUDP dynamic programming package. The DSS provides capability for graphical construction of multireservoir system networks and object oriented database development for fully dynamic optimization. The interface automatically constructs the required system state dynamics and objective function routines required for the CSUDP model. The DSS provides a powerful adjunct to the MODSIM river basin network model by performing fully dynamic optimization for development of optimal reservoir operational rules. These operational guide-curves can then be input into MODSIM for realistic evaluation of river basin management alternatives. An efficient dynamic programming successive approximations algorithm is applied for systems with up to 30 reservoirs and other system state variables. The DSS is applied to the Mahaweli system in Sri Lanka as a case study.

The Hula Aggregated Decision Support System (HANDSS) is used to assist decision makers better understand the impacts of alternative decisions in the Hula Valley restoration project in Israel. The critical link in wetlands is the interaction between the surface and ground waters. To properly manage these systems, this link must be understood. To this end, a numerical model of flow in groundwater/surface water systems was developed. This model was incorporated in a decision support system (DSS). The decisions at Lake Hula are to determine releases through a series of unlined canals. Infiltration through the canals maintains groundwater levels in the underlying peat soils. Optimization models are available in HANDSS to provide management guidance. The last component of HANDSS is visualization packages that are used to allow fast interpretation of alternative management decisions.

Karoon and Dez drainage basins located in Southwest of Iran, carry more than one fifth of surface water supplies of Iran. Two reservoirs have been constructed on these rivers and four new dams are under construction on Karoon river. Karoon and Dez reservoirs, with a capacity of over 5300 MCM and their power generation capabilities, have great importance in the Khoozestan province and in the controlling the fluctuations and power frequency maintenance of the National Power Network. In this study a Decision Support System (DSS) has been developed to assist in coordinating power and reservoir operation while satisfying other objectives. Every component of DSS has been modeled separately, and it consists of five modules: Database Management; Inflow Modeling; Inflow Forecasting; Operating model Management; and Real Time Operation. Interrelations among different modules and databases were designed in layers so that an effective framework for trouble shooting and future expansion of this system could be provided.

Quantitative techniques and computer-based models were first introduced into the water resources discipline in the early 1960s. Since then models developed for and applied to various aspects of managing water resources have evolved from "black box" paradigms to complex and comprehensive user-friendly interactive computer models. These efforts have been motivated by the apparent and increasing demand for more effective planning and policy making, and to aid in operating complex and often multi-objective and multi-purpose water resources systems. The success and effectiveness of water resources computer models in public agencies is impacted by the institutional framework in which the model was developed, the existence of an effective interface mechanism that can link modeler-model-user interactions, and the model's contribution to facilitate and support the decision making process. The "Supply and Transmission Model" (STM) was developed to support a large infrastructure master plan designed to explore a wide variety of water supply, water management and water transmission options for the Portland Water Bureau (PWB). The model is a highly interactive evaluation tool, allowing PWB staff to create a shared understanding of the model's assumptions and encourage the Water Bureau staff to explore how various future expansion and conservation alternatives will allow them to meet their water supply and natural resources management goals. The model has been created in the STELLA Research 5.1.1 simulation environment. One of the purposes of this paper is to discuss the critical factors that have contributed to the acceptance of STM as a planning decision support tool for the PWB.

A land surface model is developed to model the interaction between urban surface and atmosphere, which includes the radiation, aerodynamic transfer and soil sub-models. The model couples with a 3-D non-hydrostatic, numerical weather prediction system to investigate the weather patterns in Kanto region, Japan. The first study finds that the thermal response to surface discontinuity in Kanto results in quite strong sea-breeze in daytime and favorable to the formation of rainfall, but very weak land-breeze at night. The second study is to investigate the mechanism of heavy precipitation using one-way nesting method. The study reveals that the topography in this region plays a very important role in producing local heavy precipitation. When southerly and easterly wind approaches to the mountains at the north and west of Kanto Plain, the mountains divert the flow and cause face-to-face conflict at the narrow interface between the mountains and plain, which is an effective way to drive upward airflow. If the updraft air is warm and moist, and happens to encounter cold advection in upper layer, then water vapor condenses dramatically and heavy rainfall band forms at the narrow interface.

Design storm criteria consist of three parts: total depth, temporal distribution and the duration of the events. Since their publication, National Weather Service atlases. Technical Papers 40 and 49, and NOAA Atlas 2, have been the most commonly used sources for determining the total depth of a design storm. Soil Conservation Service (later Natural Resource Conservation Service) developed temporal distributions for 24-hour storms are widely used as the design criteria. Although the duration of a design storm would best be case specific, many permit agencies issues specified design storm durations. Water Management Districts in Florida issue their own guidance on design storms, including all three parts. In addition to the above-mentioned nationwide criteria, several Districts developed their isopluvial maps for rainfall depth for selected recurrence periods, temporal distributions for 24-hour or longer time periods, and the duration to use to design water resources structure. This paper compares these locally developed design storm criteria with Federally published ones, discusses methodologies used for developing these local criteria, and evaluates impacts of using different design storms on peak flow estimation. The paper also presents an approach to determine a proper duration to use.

Three different strategies to model dimensionless hyetographs are proposed and discussed. A dimensionless hyetograph represents fractions of cumulated rainfall over time. The storm depth at any time is normalized by storm duration. The three models employ the Beta distribution to reproduce the dimensionless hyetographs. Models 1 and 2 adopt a statistical approach while model 3 is stochastic. They were calibrated and verified over regional dimensionless hyetographs proposed by Pinheiro for the Belo Horizonte Metropolitan Region (BHMR).

A stochastic precipitation model, which is able to capture the main characteristics of heavy rainfalls in Liguria (northern Italy), has been examined to investigate the possibility to regionalize its parameters. The alternative between explicitly or implicitly taking into account the physical characteristics of a site (elevation, distance from the sea, exposition) directly or by means of the geographical coordinates has been considered. In this first approach, the comparison was restricted to the influence of elevation on the parameters of the model. It has been observed that better results have been obtained when the elevation is explicitly taken into account, even if the number of parameters of the interpolating function is lower. This seems to point out the other physical characteristics may also be regionalized explicitly, but with a greater difficulty to find an appropriate value.

As population and industry grow, water demand increases, and water supply becomes more of a problem. While reclamation of municipal wastewater for industry, subpotable domestic usage, and groundwater recharge has been practiced in the United States over the past several decades on a limited basis, similar studies need to be taken for urban storm runoff. Rainfall runoff becomes contaminated as it passes over urban land; billions of gallons of water can be recovered for beneficial uses if urban stormwater is properly controlled and treated. The water quality of the treated storm runoff can meet the required standards for subpotable usage. Accordingly, this will enable stormwater reclamation to become a more significant means of augmenting water supply. This paper discusses current urban stormwater control and treatment technologies leading to the feasibility of reclaiming urban stormwater for various purposes. A hypothetical-case study illustrating the cost-effectiveness of reclaiming urban stormwater for complete industrial supply is presented.

This paper presents information on the cost of stormwater pollution control facilities in urban areas, including collection, control, and treatment systems. Information on prior cost studies of control technologies and cost estimating models used in these studies was collected, reviewed, and evaluated. The collection phase involved identifying, screening, and consolidating publications associated with capital costs of stormwater conveyance systems and control technologies. The resulting data were evaluated to develop a critical review of costs for urban stormwater control technologies, including identification of cost information gaps and research needs.

The nation's sanitary sewer infrastructure is aging with some sewers dating back over 100 years. There are more than 19,500 municipal sanitary sewer collection systems nationwide serving an estimated 149 million people and comprising about 500,000 sewer miles. Potential health and environmental risks associated with poor performance of many of these systems highlight the need to increase federal regulatory oversight of the management, operation, and maintenance of these systems. As a result, EPA is in the final stage of preparing and issuing a SSO Rule that will add control of SSO to the NPDES permit requirements. This paper provides a preview of the Rule and describes the advantages of employing a collection system modeling approach for capacity assurance of various components of a collection system and development of SSO mitigation plan. A case study at Henrico County, VA is provided to illustrate the application of a collection system modeling approach to plan for sanitary sewer system improvements.

Available technologies were evaluated to demonstrate the feasibility and cost-effectiveness of retrofitting existing facilities to handle wet-weather flow. Cost/benefit analysis were performed by comparing retrofits to construction of new conventional control and treatment facilities. Desktop analyses were performed for 13 separate retrofit examples for 1) converting or retrofitting primary settling tanks with lamellae and/or microsand-enhanced plate or tube settling units, 2) retrofitting existing wet-weather flow storage tanks to provide enhanced settling/ treatment and post-storm solids removal, 3) converting dry ponds to wet ponds for enhanced treatment, 4) retrofitting wet-weather flow storage tanks for dry-weather flow augmentation, 5) sanitary sewer overflow control using storage, 6) retrofitting for industrial wastewater control in a combined sewer system, and 7) putting outdated/abandoned treatment facilities back online as wet-weather flow (WWF) treatment facilities. This analysis demonstrated that retrofitting existing WWF facilities can be technically feasible in most cases and may be more cost-effective than construction of new conventional control and treatment facilities. The feasibility and cost effectiveness of retrofitting was found to be a function of site-specific conditions and treatment requirements. Retrofitting processes will better enable communities to meet the U.S. Environmental Protection Agency's National Combined Sewer Overflow Policy and stormwater permitting program requirements.

The paper presents results of two case studies of Real-Time Control (RTC) alternatives evaluations that were conducted on portions of sewerage systems near Paris, France and in Quebec City, Canada, respectively. The studies were performed at real-scale demonstration sites. RTC alternatives use dynamic mathematical modeling and simulations to develop a program for a specific sewerage system to guide operation of automatic regulators when wet-weather flow is approaching. Advanced RTC alternatives also use a radar-based rainfall measurement and forecasting tool. Thus, the function of RTC-based combined sewer management is to assure efficient operation of the system and to maximize storage capacity of the existing sewerage facilities to contain combined sewer overflow (CSO) and there is cost saving aspect of this function. The first case study was conducted on a site, located northeast of Paris, France, that was a portion of the Seine-Saint-Denis combined sewer network with independent capture from other parts of the network. This site, controlled by six regulators, includes a primary settling and storage facility of 200,000 m³ capacity, which can be operated either to increase settling efficiency of the retention pond or to increase the sewer relief capacity to decrease flood risk. This case study compared two RTC alternatives: the presently used Supervisory Predictive Control, aided by a radar-based CALAMAR system, and, a simulated, Local Reactive Control, without CALAMAR. The Supervisory Predictive Control was shown to be superior.

Many enhancements have been made to the EPA Storm Water Management Model since the last official EPA release in 1994. These include improvements to the model engine, enhancements to input/output options, and "hooks" for easier interfacing with graphical user interfaces and ancillary software. SWMM is used in hundreds of applications each year in support of management of stormwater runoff, combined sewer overflows, and nonpoint source pollution. The program continues to be supported by an extensive network of users, with opportunity for feedback to code developers and GUI vendors.

EPA investigated the effects of blending disinfected combined sewer overflow samples to expose particle-associated microorganisms to the water column before measuring microbial indicator concentrations by membrane filtration. Before blending, samples were diluted in the mixture of chemicals identified by Camper et al. to enhance bacterial dissociation from solids. The resulting solution contained 10^–6 M Zwittergent 3-12, 10^–3 M EGTA, 0.01 M Tris buffer, and 0.01% peptone by weight, buffered to a pH of about 7. The results show that measured fecal coliform (FC) and Enterococcus (EC) concentrations in blended samples were up to 10 times greater than FC and EC concentrations measured in the untreated samples, i.e., unblended samples with no chemicals added. Both blending speed and time affected measured indicator concentrations, with increased concentrations observed in samples blended at 22,000 rpm from 0.5 to 3.5 min. Blending decreased mean particle size, although no correlations between increased indicator microorganism concentration and decreased particle size were observed.

The United States (U.S.) has the most extensive wastewater infrastructure system in the world. Approximately 147 million people are served by about 19,000 municipal sanitary wastewater collection systems representing about 500,000 sewer miles (not including privately owned service laterals connecting buildings to sewer mains). The operation and maintenance (O&M) and renewal activities required to support this infrastructure represent a major capital investment. The Congressional Budget Office (CBO) estimated that the total public spending on sanitary wastewater infrastructure was approximately $22 billion in 1994 alone. This represents 13 percent of total infrastructure spending in the U.S. Historically, U.S. public works managers have generally rehabilitated a component of a sewer system only after it had failed due to a break, leak or stoppage. System failures often resulted in releases of untreated wastewater to the environment and service interruptions for customers. Despite the high costs and the key role that wastewater collection systems play in servicing the public and protecting the environment, a study by the National Research Council found that few or no standards exist for evaluating their performance. In more recent years, public works managers have shifted to a more comprehensive and proactive approach to infrastructure asset management. In this framework, managers attempt to identify rehabilitation needs before they result in breaks in service or releases to the environment.

Dams and other similar hydraulic structures constructed across streams result in obstruction to fish migration. As such, fish access to spawning grounds and other habitat areas, which provide for such life requisites as food and shelter, is prevented. In many cases, fish passage facilities have been constructed at the site of the obstruction. Most of these facilities have been constructed using a hard engineering approach. Recently, increasing attention is being given to the use of nature-like fishways for facilitating fish passage. Such fishways are based on the ecological principle of mimicking nature. There are at least two different types of nature-like fishway, namely the pool and riffle type and the rocky ramp type, both of which are primarily constructed of rock. This paper is focussed on the rocky ramp type of fishway. Particular attention is given to the spacing between the isolated roughness elements to form preferential flow paths along which fish may swim. The work is based on the results obtained from physical hydraulic models of three simple geometric flow obstructions (hemisphere, cylindrical column and square column). Experimental observations and results obtained from the model study are presented. Recommendations for the spacing of isolated roughness elements are provided, along with directions for further research.

This paper deals with comparisons between Physical and Numerical Model Investigations for dimensioning an outlet of a Natural Shaped Fishway which should re-establish fish migration with very specific boundary conditions. River Leine is segregated by weirs acting as barriers for the migrating aquatic fauna. To facilitate the ascent for the aquatic fauna, the Fishway's outlet was located downstream at the outside bend of River Leine. In this outside bend. River Ihme flows into River Leine generating an eddy urging fish not to swim at the undercut slope. Therefore, this eddy had to be suppressed. Physical modeling helped finding á suitable solution to optimize the outlet of the Natural Shaped Fishway and to generate a distinct leading flow featuring frame conditions for the design of Fishways, but with a distinct smaller amount of flow inside the Fishway. Flow velocities were limited based upon swimming capabilities of the local fauna. The junction between Fishway, River Leine and River Ihme was designed with a vertical Current Deflection Wall (CDW) between Fishway and River Ihme. The cross-section of the Fishway was optimized varying cross-profiles ending up in a rectangular profile reducing friction and inducing fauna-adequate current velocities in the Fishway. Most important, a leading flow was generated distinguishable for migrating fish with a discernible current into River Leine leading fish into the weir's backwater and ensuring restoration of linear passage. In this case study, the results of the Physical Model Investigations were confirmed in a 3D Numerical Model Star-CD. It was shown, that exact and narrow-meshed bathymetric data for 3D-Numerical Simulations is essential for good results, especially in areas of higher turbulence. Based upon results of the corresponding physical and numerical model tests it was possible to obtain a suitable solution for this Fishway and future investigations on Natural Shaped Fishways.

CALFED is a cooperative venture of Federal and State water and environmental resource management agencies. CALFED's objectives are to provide improved fish protection and increased water supply reliability using the existing storage and pumping facilities. The water supply targets require considerable Delta export pumping. Efforts to reduce fish entrainment would restrict export pumping. The basic strategy is to allow the greatest possible pumping in periods with low risk of entrainment and reduce pumping when entrainment risk is high. One necessary component will be real-time fish monitoring to detect high fish densities. The second component is an Environmental Water Account (EWA) that will allow direct control over pumping restrictions necessary to reduce entrainment. A gaming approach has been used to interactively simulate the effects of fish protection measures on Delta flows and water supply conditions. A combination of a monthly planning model run in a year-by-year mode and daily operations models were used in the interactive gaming sessions. The monthly DWRSIM results for a year were used to approximate the baseline conditions that might include different facilities or operating constraints. The daily models were used to show the daily patterns of reservoir releases and Delta inflows and the effects of various Delta objectives on required Delta outflow and allowable export pumping. The daily Delta model included the historic Central Valley Project (CVP) and State Water Project (SWP) fish salvage density data, which were used to guide the EWA adjustments to export pumping in a month-by-month gaming exercise, and to calculate the fish entrainment protection achieved.

Over 8 kilometers of islands have been constructed in the floodplain of the Upper Mississippi River near LaCrosse, Wisconsin to restore fish and wildlife habitat. Islands were positioned to alter flow patterns and reduce wind-driven wave action over large areas of the floodplain. The island top elevations varied from the bankfull flood to the 10-year flood. Islands at the bankfull elevation were constructed of rock and allow flood conveyance through floodplain areas that are normally isolated during low flow conditions. Higher islands were constructed of earth, and were stabilized with rock, woody plants, and native grasses. The design of these islands was based on the habitat needs of various species of fish, birds, and animals, and on the desire to create a more riverine sediment transport regime. During low flow conditions, floodplain conveyance had to be low enough so that water velocity, temperature, and dissolved oxygen concentration were at optimum levels for winter fish habitat. During high flow conditions, floodplain conveyance had to be high enough so that erosion occurred in the floodplain. A two-dimensional hydrodynamic model (RMA-2V) was calibrated to prototype data and used to simulate flow exchange between the main channel and the floodplain for various conditions. The design of these islands is discussed in this paper.

Pogues Run is an urban stream, approximately 17.7 km (11 miles) long and draining approximately 33.7 km² (13.0 square miles), that flows into the West Fork White River near downtown Indianapolis. The lower portion of Pogues Run is enclosed in 3.5 km (2.2 miles) of underground conduit (known as the Box Culvert) through downtown Indianapolis. Due to limited capacity, the Box Culvert entrance is overtopped during extreme flooding events, creating overland flow through downtown Indianapolis and the near-east side. The current extent of the floodplain severely limits the City's revitalization and development efforts for parts of downtown and the near-east side. In addition to flooding problems, nearly the entire length of Pogues Run suffers from unfavorable water quality. While the origin of these water quality problems may not be entirely traced to the Combined Sewer Overflow (CSO) discharges, water quality in Pogues Run and the West Fork White River has seriously deteriorated as a result of 23 CSO outfalls along Pogues Run. To address the problems facing Pogues Run, a multi-million dollar comprehensive plan has been formulated in three (3) phases. Phase 1 includes construction of two multi-purpose flood control basins, modifications to CSOs, channel improvements, and removal/replacement of several bridges. Phase 2 includes consolidation, modification, and reduction of several Pogues Run CSOs. Phase 3 includes the conversion of one barrel of the Pogues Run Box Culvert into a CSO storage facility. Implementation for several elements of the Phase 1 projects has already started. Due to the multi-objective nature of the project and its funding needs, many agencies and neighborhood groups with varied, and sometimes conflicting, interests were involved. Issues such as short-term funding, handling special waste, compensatory wetland creation, allowance for dam overtopping, and even the project&s name and purpose had to be resolved.

This paper presents a novel approach for assessing flood risks in the Columbia River Basin. Colder Associates Inc. (Golder) conducted a study to assist our client in making decisions regarding flood insurance for a site in St. Helens, OR, near River Kilometer 140.8 of the Columbia River. A hydrologic model was used to combine historical hydrographs from tributary sub-basins covering the entire Columbia River Basin upstream of Longview, WA, which is very near St. Helens. The effects of the 5 largest flood control dams were included in the model. Extensive calibration was performed to ensure appropriate statistical similarity to historical behavior. The magnitudes of the contributing hydrographs were modified using a Monte Carlo analysis with a sufficient number of realizations to estimate the 100- and 500-year events with 95% confidence. Results from the hydrologic model were input to a HEC-UNET (UNET) hydraulic model of the Lower Columbia River to predict river flood stages at St. Helens.

The goal of this hydrologic study was to develop a calibrated hydrologic model that would help assess effects of current and future land use on watershed runoff. The rainfall-runoff model was developed and calibrated to actual gaged data. The hydrologic computer model that was used in the analysis was the U.S. Army Corps of Engineers Hydrologic Engineering Center's rainfall runoff model titled HEC-1. The first step in calibration included optimization of unit hydrograph parameters for historic rainfall events at gages within the watershed and in nearby, hydrologically similar basins. The optimized unit hydrograph parameters, watershed characteristics and percent imperviousness used as an index of urbanization, were combined into a regional equation with a multilinear regression analysis. The regional equation was used to predict unit hydrograph parameters for ungaged basins in the watershed. The second step in calibration included adjustment of the loss rates in the basin so that the discharges predicted by the HEC-1 model at the USGS gage location matched the discharge frequency curve. The calibration insures that the 100-year precipitation generates the 100-year flood. The calibrated hydrologic model will be used by the Watershed Management Organization to assess the effects of existing and future land use on watershed runoff.

Dry Creek drains about 22.6 square kilometers of rugged mountainous terrain upstream from Tabor Dam in the Mission Range near St. Ignatius, Montana. Because of uncertainty about plausible peak discharges and concerns regarding the ability of the Tabor Dam spillway to safely convey these discharges, the flood hydrology for Dry Creek was evaluated on the basis of three hydrologic and geologic methods. The first method involved determining an envelope line relating flood discharge to drainage area on the basis of regional historical data and calculating a 500-year flood for Dry Creek using a regression equation. The second method involved paleoflood methods to estimate the maximum plausible discharge for 35 sites in the study area. The third method involved rainfall-runoff modeling for the Dry Creek basin in conjunction with regional precipitation information to determine plausible peak discharges. All of these methods resulted in estimates of plausible peak discharges that are substantially less than those predicted by the more generally applied probable maximum flood technique.

The National Oceanic and Atmospheric Administration installed a Physical Oceanographic Real Time System (PORTS) in June 1996 in Galveston Bay, Texas. Water surface elevation, currents at National Ocean Service prediction depth (~4.6m below MLLW) as well as near-surface and near-bottom temperature and salinity, and meteorological information are available at six-minute intervals. This real time information source is used by water resource planners and to promote safe navigation. Specifically, to complement the PORTS, a nowcast/forecast system has been developed for the Bay using a modified version of the Blumberg-Mellor three-dimensional hydrodynamic model and a one-way coupled fine resolution Houston Ship Channel model. For the nowcast, PORTS measurements are used to provide the hydrodynamic model forcings. During the forecast the National Weather Service's Aviation atmospheric and Extratropical Storm Surge Forecast Models are used to provide the meteorological and Gulf of Mexico subtidal water level forcings, respectively. The results are presented for several demonstration periods during which daily 24-hour nowcasts and 36-hour forecasts were performed using both bay and channel models in a pseudo-operational setting. The nowcast and forecast are separately evaluated for the accuracy of water levels, currents, salinity, and temperature. Evaluations of forecast Gulf of Mexico subtidal water level, freshwater inflows, and wind and sea level atmospheric pressure are also considered. In conclusion, the present system status and a strategy for continued development in a user directed GIS framework are discussed.

The National Weather Service (NWS) one-dimensional, unsteady flow dynamic routing model FLDWAV has been applied to the Red River of the North and is being implemented into the NWS River Forecast System (NWSRFS) for real-time river forecasting. The model was calibrated using the 1997 historic flood data and verified using 1978, 1979, 1996 and 1999 data. The results show that the FLDWAV model is capable of modeling the complex hydraulic effects experienced in the 1997 flood, such as the significant backwater, flood plain water storage and drainage conduit blockage in very large and flat flood plain areas.

Optimization modeling can be used as a design and a planning tool in the selection of the "best" drainage alternatives for engineering projects. The approach was used for the Middle New River Watercourse Plan to evaluate five drainage design concepts that would safely convey design floods previously defined in studies conducted by the U.S. Army Corps of Engineers and the Flood Emergency Management Agency (FEMA). Due to varying development density along the Middle New River, the entire study reach was divided into sub-reaches. Each sub-reach was subject to site-specific design requirements and therefore modeled accordingly. The optimization models searched for and evaluated optimum design configurations for the drainage project based on the governing system equations employed. Important governing equations used in the procedure included the continuity and Bernoulli's equations for flow hydraulics, and scour equations for bed dynamics and channel mobility. Using economic performance as the objective function, the optimization models were formulated to evaluate the optimum channel configuration that provided the least project cost. Cost components included channel excavation and earthwork, hydraulic structures, acquisition of right-of-way and drainage easements, revegetation work, salvage, mobilization, engineering, contingency, operation, maintenance and repair. The resulting nonlinear optimization problems associated with the five design alternatives considered were solved using GAMS-MINOS, an optimizer code developed by Brooke et al.

The purpose of this research is to develop a dam breaching mathematical model, which takes into account the three-dimensional structural stability of the embankment and the spatial variability of the soil parameters. The erosion part of the model was developed by using and modifying some of the available breaching models such as the Fread Breach Model. The three-dimensional structural stability analysis part of the model was developed by the author. The spatial variability of the soil parameters was taken into consideration using Monte Carlo method. For the stability analysis, in addition to the Monte Carlo method, the nearest-neighbor concept, extended for three-dimensional simulations, was used to get a set of correlated soil parameters for the analysis. The model showed close prediction for the breach parameters for both Mantaro Dam and Teton Dam actual failure cases. The spatial variability analysis showed a suggested distribution for outflow, three-dimensional factor of safety, and the breach area.

Jackson Mississippi has been the victim of severe flooding over the past 25 years. During this period, the communities along the Pearl River through Jackson and downstream to Columbia, Mississippi, have struggled to develop flood control options which improve the situation for everyone. Levees, reservoir operational changes, and new impoundments have been proposed without reaching consensus. This leaves these communities with worsening conditions that increase their vulnerability each year. The most recent proposal has been to build two contiguous lakes downstream of the Ross Barnett Reservoir through the Jackson area. These lakes would not have active gated outlet structures, but would have passive weirs controlling discharges from each lake. Hydrologic and hydraulic analyses of the proposal were performed to evaluate the claims made by the project proponents. This paper will discuss the results of the analyses and describe the interests involved and how they would be affected by the project.

Topographic surveys have been conducted for the Feather River basin to support hydraulic model development for a large planning study. The survey consisted of traditional photogrammetry as well as two variations of light detection and ranging (LIDAR). A preliminary comparison is made between the resulting LIDAR and photogrammetric mapping products and the differences are discussed herein. The comparison focuses on the gross accuracy and appropriateness of using LIDAR mapping to support hydraulic modeling of rivers and their floodplains.

The U.S. Army Corps of Engineers (USACE) operates Addicks and Barker Reservoirs to reduce flooding along Buffalo Bayou through the City of Houston. Extensive urbanization occurring throughout the watershed and floodplain during the past 50 years includes commercial and residential development adjacent to reservoir lands upstream of the dams. Reservoir stage-frequency relationships provide basic information required in analyses of the upstream flooding potential. A methodology for determining reservoir stage frequency relationships was adopted that includes three phases: (1) adjusting historical sequences of daily stream inflows for the effects of urbanization, (2) simulating reservoir operations, (3) performing a frequency analysis of the resulting annual series of peak reservoir stage. The first phase is accomplished using a computer program called FlowAdj, that is based on the NRCS CN equation. FlowAdj was developed in conjunction with the study. The second and third stages are performed using the HEC-5 and HEC-FFA computer programs developed by the USACE Hydrologic Engineering Center.

In water projects often it is said that the project is designed or protected at a level of x-year return period. But this x-year design (or protection) return period is often misunderstood. Part of the misunderstanding comes from inadequate appreciation of probability. The more serious problem is that the X-year return period of what is not clearly specified. For instance, urban storm sewers are designed based on X-year return period of rainfall, not of flood. On the other hand, spillways are designed for a flood of X-year return period. The protection level of the land behind a levee has a return period different from the 100-year return period of the flood stage, of the peak discharge used in the design of the levee. The objective of this paper is to point out these differences and their implications in water engineering design and management.

An environmental information system (EIS) was developed and implemented for the Bolivian government. The purpose of the system is to support the administration of mining activities on a countrywide scale. The EIS is shared by three government agencies that are collectively responsible for this task. The principal functionality of the system is to predict the impact of past, present and future mining activities on air, surface water and ground water quality and associated risk to human health. The foundation of the system is a geographic database. The database contains information related to mining and the environment (e.g. discharge points and streams). Basic database management functionality (e.g. zooming and layering) is provided by standard, off-the-shelf geographic information system (GIS) software. To supplement the standard GIS functionality, several customized tools were developed. These tools consist of three metal fate and transport models, a risk analysis module and a cost/benefit module. The tools are fully integrated into the graphical user interface (GUI) of the GIS. Sharing a common information system allows the three agencies to centralize and integrate all mining related data, therefore promoting inter-agency relationships. The development of the GIS emphasized the importance of a too often-overlooked component of an information system: the user. An information system is comprised of three parts: (1) data, (2) software and hardware and (3) users trained and experienced in the use of the system. Finding users that are proficient in the use of GIS technology, fate and transport modeling and human health risk analysis was a challenge. Therefore, the system was designed to be as user-friendly as possible and an extensive training program was conducted. Training governmnent employess in the use of the system provided an opportunity to foster additional cooperative relationships between the involved agencies, each of which will tend to focus on one aspect of the EIS' capabilities.

Economy is growing and cargo transport is growing in parallel even faster. Therefore alternatives to truck transport and congested railways are necessary. Cargo transport on inland waterways provides space, capacities, safety, environmental friendliness, less energy consumption and high efficiency, whereas speed is a major disadvantage of present inland ships for cargo transport. Investigations upon operation of high speed inland ships for cargo transport showed, that they can be integrated in transport chains. Simulations showed, that driving durations can be provided as known from cargo transport by truck and railway, depending on size, amount of locks, and traffic density of inland waterway. Therefore accelerating ships' speed of present inland ships for cargo transport, would increase attractivity for cargo transport on inland waterways. This increases hydraulic impacts because of restrictions and shallowness of inland waterways, resulting in increased ship-generated water level variations and reverse flow velocities compared to present inland ships for cargo transport. This might affect stability of inland waterways' banks and bottoms, and also the navigational safety.

Cross currents induced by lateral water introductions possibly influence ship operation on inland waterways by calling forth transverse movements of a ship while passing the cross currents influenced zone. In order to provide operational traffic safety on inland waterways these transverse movements are to be restricted by developing a suitable introduction construction for the lateral water introductions. As a rule, there are to steps to do. In a first step, the dimensions of the introduction construction are to be estimated based on theoretical appoaches. In a second step, physical model tests are to be carried out in order to check and if necessary to guarantee the hydraulic effectiveness of the introduction construction. Exemplarily for a lateral water introduction of a Rainwater-Collection-System of the city of Bamberg, Germany into the Main-Danube-Canal the above mentioned general proceeding for developing a suitable introduction construction for lateral water introductions into inland waterways considering defined boundary conditions is explained in detail showing especially a state-of-the-art theoretical approach for estimating the dimensions of the introduction construction. In this case the physical model tests were carried out in model flume. Cross current velocities at the outlet of the introduction construction were measured and transverse movements of a ship passing the introduction construction were documented. The results of the application example showed that the dimensions of the introduction construction could be estimated as a base for the physical model tests sufficiently exact using a theoretical approach considering the defined boundary conditions. In the physical model tests the hydraulic effectiveness of the introduction construction could be guaranteed by using constructive measures like bended current deflection walls, bended submerged walls and sills as well as current reflection walls resulting in suitable introduction construction for the defined boundary conditions.

A geographic information system (GIS) application to stream navigability is presented in this paper. The work involves the study and analysis of all small and minor watercourses in Arizona aimed at identifying those streams that exhibited characteristics of navigability at the time of Arizona' statehood in 1912. A three-level screening approach is developed for the watercourse classification. Level 1 analysis employs six diagnostic stream attributes that have potential bearing on the navigability question. The watercourses that survive the first screening process are forwarded to Level 2 analysis which employs a qualitative approach and an in-depth investigation of the stream attribute data. Level 3 evaluation involves an engineering analysis of the hydrology, hydraulics, and geomorphology of streams and these are evaluated against known and established boating criteria. The result of the multi-level approach is a short-list of watercourses recommended for detailed study that will compile historical and technical evidence for final stream classification.

A GIS-based AGNPS modeling system, a system of ArcView scripts and associated controls, has been developed for assessing nonpoint source pollution at the watershed scale. The integrated GIS modeling system can estimate runoff and pollutant loading from a watershed, allows users to make a detailed comparison of the effects of diverse land uses, landscape features, and land management scenarios on water quality in a designated watershed. A map-based display of AGNPS modeling outputs, rather than a numerical text file from the model, provides critical areas of erosion and pollutant movement within the watershed. This paper describes the development of an integrated system that uses object-oriented Avenue language and Visual Basic language. The system provides a user-friendly interface with pre-processor and post-processor for the AGNPS model. This new approach allows the application of a more comprehensive model that previously could not have been discretized to such a high level of detail. This integrated system was applied to a coastal plain watershed to demonstrate its capabilities.

Ground-water contamination by pesticides and other organic pollutants has been detected across agricultural areas and is on the increase. Because ground-water monitoring is too costly to define the geographic extent of contamination at such large scales, indirect methods are needed to predict transport and fate of pesticides in the subsurface and assess the potential for ground-water contamination that may result from applications of pesticides. In this paper, two analytical solutions that describe one-dimensional transport and fate of pesticides in the soil, were integrated with a geographic information system (GIS) to estimate spatial solute leaching distributions and to create ground-water vulnerability assessment maps. The GIS-based models use process-based equations that consider advection and complete mixing to simulate solute transport and to predict pesticide transport in both space and time. To demonstrate its capabilities, the modeling approach is applied to an agricultural watershed in the mid-Atlantic coastal plain using data from county soil survey and monitoring study in this region. The impact of processes, such as net infiltration, biochemical degradation, adsorption and advection on the spatial and temporal distribution of pollutant emissions to ground water are investigated. The applicability of GIS-based models for vulnerability assessment and determining the risk of ground-water contamination by pesticides is demonstrated in susceptible agricultural areas.

In today's environmental engineering practice, many computer models have been developed which explain physical and chemical processes in lakes, streams, and estuaries. These computer models rely heavily upon data for the development of model parameters as well as for the calibration and validation of model results. In the past, the working connection between data and the model, both of which exhibit spatial variability, has been relatively weak. The utilization of Geographic Information Systems (GIS) has improved data analysis, model development, and presentation of model results by strengthening the link between data and water quality models. This paper outlines the following: 1) The process implemented in importing the data and model information into GIS. 2) The methods of data analysis exercised to study the environmental problem, 3) the development of various model inputs, and 4) the discussion of comparison between model output and actual data. This environmental modeling effort has benefited from the use of GIS for data analysis and model development, as well as presentation of model results for model calibration and projections. Not only has it saved considerable time and effort in the development of the model input, it has also assisted in the clear and efficient presentation of results to clients. The success of GIS in the project presents a strong argument for its use as a universal tool in future water quality modeling and management efforts.

Water Quality Analysis Simulation Program WASP5 was applied to the Chi-Shui River in southern Taiwan to simulate the distribution of BOD and DO concentrations. After model calibration and confirmation, the model was used to investigate the water quality conditions under design flows. Furthermore, considering the uncertainty of model parameters and input data, risk analysis techniques, including Monte Carlo simulation, mean value first-order second-moment method, and advanced first-order second-moment method were used to calculate the probability of BOD and DO concentrations in violation of river water quality standards. Finally, the results of risk analyses from different methods are compared and discussed in this paper.

Dissolved gas caused by reservoir spillway releases continues to be a large problem in the Columbia River Basin. Concentrations routinely exceed the 110% target levels and even the 120% waiver values during maximum spill periods. The US Army Corps of Engineers and other dam operators are spending a great deal of time and resources trying to reduce these gas concentrations. Efforts include physical model construction and evaluation, installation of so-called "flip-lips" to keep spillway discharges from entraining as much gas, constant monitoring of gas concentrations, and numerical modeling. Most of the monitoring effort has been in the immediate vicinity of the spillway or at a single fixed location approximately 1 mile downstream of the spillways. This project, however, examined both lateral and vertical variations in dissolved gas concentrations as a function of depth and lateral location. Monthly samples were taken at eight cross-sectional locations along two reservoirs. Spatial and temporal changes in dissolved gas concentrations were examined. Correlations to other water quantity/quality parameters such as discharge, dissolved oxygen, pH, temperature and nutrient concentration were also examined.

Central Puget Sound includes three of the four largest and fastest growing counties in Washington state: Snohomish, King, and Pierce. Three city public utilities (Everett, Seattle, and Tacoma) supply water from four water reservoirs to most of the population in these counties. These agencies face common challenges, which include meeting increasing instream flow requirements, providing water to growing wholesaler populations and developing new water supply sources. One alternative to costly new water supply development is regionalization: connecting the supply systems, promoting the transfer of water rights and making more efficient use of existing sources. A regional water supply model is presented that evaluates the benefits from interconnecting the three utilities and managing the supply system from a regional perspective. The results indicate that sufficient storage exists in the Everett system to supply the region through 2040 demand projections. An Everett— Seattle intertie (ESI) improves long-term supply availability, provides needed supply redundancy for the Everett system, and can enhance instream flows in the Cedar and South Fork Tolt Rivers. When the intertie is operated only during low flow years, the same water supply benefits are derived, but the enhancement of instream flows is decreased.

The Ohio River Valley is one of the most heavily industrialized basins in the United States. As a result, the Ohio River and its tributaries often experience poor water quality. One measure of poor water quality is low dissolved oxygen concentrations during low flow periods. Most of the rivers in the Ohio River Valley have been transformed into navigable waterways through a series of locks and dams. The free flowing river is now a series of pools. Quiescent pools do not promote the transfer of oxygen into the water due to low turbulence levels. Fortunately, the hydraulic structures themselves may actually be the key to improving the water quality because of the high turbulence levels and air entrainment generated at these structures. Field experiments were performed at several low-head structures, called gated sills, in the Ohio River Valley to determine the oxygen transfer capability. Methane was used as a tracer gas to determine oxygen transfer. The amount of oxygen transferred to the water varies with structural characteristics, gate opening, and hydraulic conditions. From the data collected at several sites, the factors that influence the transfer efficiency of a structure have been determined. The key to achieving higher transfer efficiencies lies in the ability to form an unsubmerged hydraulic jump. A submerged hydraulic jump will achieve less than 15% transfer efficiency, while an unsubmerged hydraulic jump will achieve much higher transfer. Sill submergence is also important for determining transfer efficiency. Sill submergence will govern whether an unsubmerged hydraulic jump can form, and lower submergence will result in higher transfer.

This paper describes the mechanics of flow over and through a Coanda-effect screen, a unique type of self-cleaning screen constructed from wedge-wire panels installed on supercritical slopes. The paper presents a numerical model for determining the flow rate through a Coanda-effect screen and discusses the variation of screen discharge capacity as a function of screen geometric parameters and the Froude number of the flow over the screen. The model was developed and calibrated using data collected in laboratory tests of several different screen configurations, and can be used to evaluate the hydraulic performance of custom designs, which should facilitate future application of Coanda-effect screens.

The Joint Operations Plan (JOP) is a cooperative venture among the cities of Fort Collins and Greeley and an agricultural company, Water Supply and Storage Company (WSSC), to provide winter flows for enhanced fisheries in the National Forests of the Poudre River basin in northern Colorado. The JOP was developed as an alternative to bypass flows. In essence, the JOP provides twice as much water (285 L/sec) as bypass flows would have to 97% of the affected trout habitat during the critical, low-flow winter season. This paper discusses the acrimonious evolution of the JOP and the gratifying results of the first two years of operation.

The Minnesota River drains one-fifth of the state of Minnesota and is a major tributary to the upper Mississippi River. Intensive row crop agriculture is the primary land use in the basin. To develop higher crop yields, both surface and subsurface drainage were applied to the landscape over the 20^th century. A 1989–1993 watershed assessment study suggested a linkage between degraded water quality and land-use changes, particularly agricultural drainage. Twelve USGS gaging stations with extensive flow records located in the Minnesota River basin were analyzed for changes in peak flow for frequent events. Twenty-five USGS gaging stations across the Minnesota River basin representing varying drainage areas were analyzed for field morphological features. Stream reaches were classified using Schumm's channel evolution model and Rosgen's stream classification system. Results suggest that wetland and prairie-lake conversions to cropland have increased runoff contributing drainage areas. These changes, along with changes in climate, are reflected by increased flows in frequent events (1.01-year, 1.5-year, 2-year recurrence intervals) throughout the century. Field evidence of channel incision was observed in the Yellow Medicine, Chippewa, Cottonwood, Blue Earth and Rush Rivers. Increases in the bankfull, channel-forming discharge have resulted in channel degradation, which disconnects the channel from the active floodplain. The resultant loss of the active floodplain has destabilized riparian vegetation, habitat and the riparian corridor's ability to buffer environmental stress. Subsequent channel adjustments following incision have resulted in land loss and increased sediment loads in the unstable channels. Some of the increased sediment loads were deposited in downstream, widened reaches, but silts and clays were transported further downstream as an increased suspended-sediment load.

The Restoration of rivers in watersheds with historic mining districts has become a topic of interest during the last decade. Rivers restoration in these areas is difficult because the mines and mills can be scattered over a wide area and often small. Many have also been abandoned. This paper presents two substrate related factors that are important in the evaluation of river restoration alternatives in watersheds with significance impacts from mines and mills most of which are old and abandoned. The two factors are 1) changes in the size distribution and specific weights of the substrate, and 2) the changes in quality of the interstecial waters caused by metals associated with the tailings in the substrate. The most important impacts of tailings from mills may be on the physical characteristics of the substrate (porosity) and on the quality of the pore waters. The measurements presented in this paper do show significant variation in the porosity in gravel bed rivers and in the quality of the pore waters.

In this paper some general design considerations and principles for flood protection and related stormwater design, based on an integrated environmental approach, involving less technical works and preservation of the physical condition of streams and creeks are presented. Sediment control through check dams and the selection of design return period are discussed. The design period should be selected depending on the specific location, the associated design of the receiving stream or water body, and considering the consequences of a bigger flood than the one used for the design. The application of the above mentioned considerations is illustrated in two specific case studies (introductory study for Kifisia and the preliminary study for northern suburbs), carried out by Hydroexygiantiki for areas in the northern suburbs of Athens on behalf of EYDAP, a public company responsible for the water supply and sewage system of the Athens Metropolitan area. The proposed design in each case took into account the special problems and the views of the local authorities in order to ensure that the proposed design is a viable one. Of course it should be always kept in mind that the selected design should be implemented starting from the downstream end and special care should be used in main road crossings.

Numerous measures have been proposed to characterize the fractal characteristics of streams and stream networks. The performance of these measures has not been tested and compared for real watershed data. In this study, these dimension estimates are computed and compared for several Indiana watersheds. The variability in these dimension estimates are discussed.

The California Department of Transportation (Caltrans) constructs, operates, and maintains the state highway system in California. Stormwater runoff from Caltrans construction sites and roadways is subject to the federal Clean Water Act and its associated NPDES permit program. Caltrans began implementing a Statewide Storm Water Management Plan (SWMP) in 1996. In conformance with EPA directives, Caltrans control efforts have focussed on "best management practices" (BMPs) to control sources of pollutants in storm water. For the most part, BMPs consist of common sense pollution prevention techniques rather than use of structural treatment facilities. The same approach, using non-structural controls, has also been applied to urban runoff from large regulated municipalities and runoff from construction sites. During 1999, the regulatory climate for storm water management in California changed dramatically. New permit requirements will require methods that achieve higher levels of pollutant control than are achieved by conventional BMPs. The statewide storm water permit recently issued to Caltrans, as well as other recently issued municipal permits, require that storm water discharges comply with established water quality standards. Compliance with these standards is a significantly more stringent requirement than was previously applied to these discharges. Also, limited information is available regarding the technology and other controls that can be used to meet these more stringent requirements. Caltrans has modified its Storm Water Management Plan to incorporate this new goal. In addition, Caltrans has initiated an extensive research and pilot-testing program to identify technologies that can be used to meet water quality standards.

The California Department of Transportation (Caltrans) District 11 discharges storm water from facilities and properties within its right-of-way to various waterbodies in the San Diego area. The impact of these discharges on the waterbodies varies according to the Caltrans activity, waterbody beneficial uses, and existing water quality conditions. To minimize this impact and provide the most benefit to the waterbody, constituents and waterbodies of concern for storm water discharges from Caltrans facilities in District 11 were identified. Identification of constituents and waterbodies was based on an assessment of Caltrans discharges as compared to impaired waterbody listings (303(d) list, etc.) and receiving water and storm water studies conducted by local and regional agencies. Stormwater monitoring data collected from Caltrans facilities throughout Southern California were used as the basis for the water quality assessment. When sufficient data were available for a constituent, the 95^th percentile concentration was determined and compared to water quality objectives outlined in the Water Quality Control Plan for the San Diego Region (Basin Plan). Constituents with 95^th percentile concentrations exceeding appropriate objectives (assuming no dilution) were considered potential constituents of concern for Caltrans discharges.

The California Department of Transportation (Caltrans) has initiated a multi-year study in Los Angeles and San Diego to examine the technical feasibility, costs and operation and maintenance requirements of retrofitting structural Best Management Practices (BMPs) into existing highway and related infrastructure. Thirty-three locations are being retrofitted with thirty-nine BMPs using twelve different types of BMP technology. Automated monitoring stations have been installed upstream and downstream of each BMP. Constituents monitored in the runoff include: suspended solids (e.g., sediment), metals, nutrients, and organics (e.g., gasoline). Data currently being collected will show how much each constituent is reduced across each BMP. To date the projects have been sited, designed, constructed and monitored (for the first year). The purpose of the program is to identify the problems, and the solutions to those problems, that occur with structural BMP retrofit. Results to date indicate that there are substantial construction, maintenance, and cost challenges in retrofitting conventional structural BMP technology to existing infrastructure.

Trash and debris in storm water is a threat to aquatic wildlife, is aesthetically unpleasant, smells, can reduce drainage conveyance capacities, and can attract vermin. Despite improved awareness and increased spending on litter control, data on the movement of litter and debris through urban areas are scarce. This paper describes a two-year monitoring project, conducted in the Los Angeles region, that assesses the performance of several Best Management Practices (BMPs) intended to reduce the quantity of litter in freeway runoff as part of a Caltrans Litter Management Pilot Study (LMPS). Measurements of rainfall, runoff, and the amount of litter and debris [defined as material larger than five millimeters (1/4 inch)] are taken at both control sites and sites where BMPs are employed (treatment sites). The unique litter sampling equipment, the BMPs adopted, and the methodology are described, and some preliminary monitoring results are presented.

Hydraulic structures, such as dams, spillways, and grade control structures, are now often designed utilizing roller compacted concrete (RCC) and soil-cement. Designing structures with these materials began before the 1980s and is now an often selected alternative because of its in-service proven performance and economics. he economic advantage RCC and soil-cement has over other materials is because the construction methods that are employed result in shorter construction schedules. RCC and soil-cement are placed using equipment typical of earth moving operations which can achieve high production rates. Shorter construction schedules minimize the risks associated with construction in a flood plain environment and therefore allows the contractor to reduce contingency costs for potential flood damages. RCC and soil-cement water resources structures have now been in service for over 20 years and have shown exceptional durability in severe climates and during significant flood events. RCC is chosen as the principal material when high velocities are expected or heavy bed loads are likely because it is very resistant to abrasion. Soil-cement is the material of choice when infrequent moderate velocity flood flows are expected for protection of riverbanks and for grade control structures.

The Spokane River is a steep-gradient river that flows through the City of Spokane in eastern Washington. Large-sized sediments are eroded and transported down the river, with significant quantities deposited upstream of Avista Corporation's Monroe Street Hydroelectric Dam intake in the downtown area of Spokane. The impacts are river degradation, erosive damage to equipment, and disturbance of normal intake operations. Consequently, work crews must remove the sediment, which has typically been accomplished with disruptive and costly dredging operations. The major thrust of this study is the proposition of a new strategic plan for river restoration not based solely on qualitative assessment, but developed using quantitative analysis. This research utilizes two-dimensional hydrodynamic modeling, FESWMS, to map the flow patterns in the river. The results are used to identify and isolate areas of accelerated sediment erosion, and to develop river restoration methods to control upstream erosion.

Spillway design and maintenance is a risk source for dams in general and, particularly, for embankment dams. Spillway's malfunction can cause. Stability problems to dam embankments and put in risk properties and population living downstream. The choice of the type spillway for an earthfill dam should be decisive. Those devices can cause problems in the stability of the embankment and to cause damages to neighboring populations. This paper presents a case study on the instability of embankment of an earthfill dam in urban area, caused by malfunction of the morning-glory type spillway.

Numerous studies have been performed to determine the discharge coefficient for orifices. These studies have included a variety of shapes, sizes, and configurations. The values developed typically ranges from about 0.6 to 0.85. However, specific discharge coefficient values for a particular configuration often appear contradictory. This is probably a result of variations in testing methods and operating conditions. The effect of submergence is also not specifically identified as a parameter for determining the discharge coefficient. Therefore, it is difficult to confidently select a discharge coefficient value from the available literature for an orifice operating under different levels of submergence. For this reason, a physical model was constructed at the Iowa Institute of Hydraulic Research to determine the effect of submergence on a rectangular orifice with partially suppressed contractions. The model results demonstrated that the discharge coefficient varies from about 0.6 to 0.85 depending on the magnitude of the submergence.

Version 1-0-0 of FLDWAV, a flood routing program developed by the National Weather Service (NWS) and released in November 1998, is intended to replace NWS DAMBRK and DWOPER programs used widely in recent years. Several enhancements have been added to the new program, and one of the distinguishing features of FLDWAV as compared to DAMBRK is its capability to model a system of interconnected waterways while DAMBRK models only single waterways. The Sevier River in central Utah with seven major dams and a major tributary affords a good system for the application of these models. In this paper, a combination DAMBRK and FLDWAV model of the Sevier River is described. FLDWAV is used to model the reach of the river which has a tributary with a dam, and DAMBRK is used for the remaining reaches with dams on the main stem.

An extended relaxation technique is developed to simulate unsteady flows in river channel networks and the technique is implemented into the National Weather Service dynamic wave routing model FLDWAV. The new technique is an extension of the original relaxation method in the FLDWAV model initially developed for dendritic (tree-type) channel systems. This technique greatly increases the FLDWAV model's capability to model any complicated river network system which includes complex bifurcations. Some test results illustrating the technique's accuracy, robustness and computational efficiency are reported in this paper.

The heat produced at the water surface by infrared (IR) radiation and subsequent cooling is used as a tracer to infer characteristics of the large flow structures in an open channel flow. These large flow structures, labeled large streamwise vortices, are visualized at the free surface through the use of an IR video camera during the cooling period. The upwelling regions cool more rapidly than the downwelling regions. The location of large flow structures may be identified because of the upwelling and downwelling character of these flow structures. The length scales of the large flow structures are compared to the scales of the flow field.

Cherry Creek Dam, south of Denver Colorado, was constructed in 1950. Updates in the procedures to estimate the probable maximum precipitation have resulted in the dam being determined as hydrologically deficient. As part of the dam safety study, routings were required to determine downstream inundated areas, to calculate the population at risk, and to calculate potential economic damage from a dam failure. Since HEC-2 models were available for the area, these dam failure routings were done with the UNET (Unsteady Flow in a Full Network of Channels) and HEC-1 models. HEC-1 was used to route the flow into the dam reservoir and calculate the dam breach hydrograph. The UNET model was used to route the dam failure hydrograph about 35.4 kilometers (km) (22 miles) downstream past the Cherry Creek-South Platte River confluence. HEC-2 cross sections were used as input in the UNET model and prevented the need to translate to another format. UNET output was written to text files and DSS (Data Storage System) allowing graphical review of the hydrographs, conveyance curves, stage, and discharge calculations. The UNET model was able to show negative flows upstream from the Cherry Creek-South Platte confluence. These calculated water surface elevations were used in plotting flooded area boundaries using a Geographical information System (GIS) algorithm in ArcView.

A canoe chute is a series of rapids and pools creating a gradual descent from the elevation of the upstream pool of the dam to the elevation of the pool at the toe of the dam. Each rapid forces a surface jet that causes a hydraulic jump when it enters the slower water of a pool. Most engineering designs have considered the hydraulic jumps formed in canoe chutes to be approximately the same as the hydraulic jumps formed at abrupt drops in the channel bottom. The jumps commonly observed at abrupt drops are A-Jumps formed at high tailwater conditions, waves formed at intermediate tailwater conditions, and B-Jumps formed at low tailwater conditions. Sets of equations have been developed by different authors to describe the A- and B-Jump types that occur at abrupt drops. In a canoe chute, however, there is also a simultaneous horizontal expansion in the channel in addition to an abrupt drop in the channel bottom. Thus, the momentum equations that describe two-dimensional flows at abrupt drops need to be modified to account for the three-dimensional flow caused by the additional horizontal expansion. A 1:7 scale Froude model of one rapid of the canoe chute was constructed in the Ven Te Chow Hydrosystems Laboratory at the University of Illinois. Depth and flow data collected from the physical model were compared against both the original and the modified momentum equations. An empirical method for predicting hydraulic jump behavior was developed. The empirical method is advantageous in that it involves either known or easily measured flow conditions.

Three non-dimensional numbers are used to explore how the peak outflow changes at a dam breach section. The non-dimensional numbers are Dam Breach Number, the ratio of final breach width to depth, and the side slope of a breach section. It is shown that the Dam Breach Number is the dominant factor that affects peak outflow. The ratio of breach width to depth and the side slope have increased effects on peak outflow when the Dam Breach Number is greater than 1.

Three-dimensional Computational Fluid Dynamic (CFD) models can provide a wealth of information for flows in complex channel geometries that is not attainable in physical model studies and that is free of scaling effects. This paper reports a validation study for such a technique employed for a proposed flood channel realignment study on the Arroyo Mocho in Livermore, California. The numerical model solves the steady-state, fully-three-dimensional, Reynolds Averaged Navier Stokes (RANS) equations in generalized curvilinear coordinates with a standard k-ε model and wall functions. The channel realignment includes several complex geometric features: two drop-structures, two ninety-degree bends, and two forty-five-degree bends. The main purpose of a physical and numerical modeling study was to evaluate super-elevation and near bank velocities induced by the resultant highly three-dimensional flow. Calculated velocity profiles are compared to measurements obtained in a physical model study reported by the University of California, Berkeley and TRS Consultants, Inc. The present comparison indicates mixed results in model performance. Generally, comparisons between calculations and measurements are good. However, discrepancies observed in some of the profiles require further investigation before proceeding with the numerical modeling study.

This paper presents the hydraulic characteristics of a doubly meandering compound channel. The experiments are carried out in a 30 m long and 1.5 m wide tilting flume. One important feature of this doubly meandering compound channel is that there is a phase difference of 30° between the main channel and the outer levee. Two types of flow conditions are examined viz.: shallow water condition and deepwater condition. The water surface fluctuation, stream-wise velocity distribution and secondary currents are analyzed. It is found that the stream-wise velocity tends to deviate from floodplain to main channel and from main channel to floodplain. The degree of deviation is higher for shallow water condition than deepwater condition. The maximum deviation occurs at the cross-over section for both shallow and deepwater water condition. The exchange of flow between main channel and floodplain drives secondary flow cells in the main channel as well as in the floodplain. The anti-clockwise cell grows along the inner bank of the main channel, reaches its peak at a section in between the cross-over region and the bend apex next to the cross-over region and decays immediately upstream of the bend apex. The opposite thing happens in the next bend. The evolution and decay process of secondary currents is virtually the same for both shallow and deepwater condition. In case of shallow water condition the mound of water is observed along the main channel-floodplain interface and in case of deepwater water condition the mound is observed along the side of the flood levee.

A two-dimensional (2D) hydrodynamic and salinity model of Florida Bay has been developed to study the effect of freshwater releases on circulation and salinity distribution in the Bay. The model has also been used to provide flow fields to a 2D water quality model of the Bay. The TABS-MD system model RMA10-WES (or TABS-MDS) was employed in a 2D mode to calculate water level, current velocity, and salinity at each computational point in the numerical grid. To provide data for boundary conditions and for model verification, a field data collection effort was conducted by the U. S. Army Engineer Research and Development Center (ERDC) during March 1996 through April 1997. Water surface elevations, salinity, velocity, and water flux data were collected. In addition, data from the National Park Service (NPS), Harbor Branch Oceanographic Institute (HBOI), South Florida Water Management District (SFWMD), the U.S. Geological Survey (USGS), and the National Oceanic and Atmospheric Administration (NOAA) were used in the development and verification of the model.

The South Florida Water Management District wished to develop an integrated groundwater/open-channel flow model by linking the Corps of Engineers' UNET model with the USGS model, MODFLOW. The coupled model, called MODNET, provides the District with the capability of simulating three-dimensional groundwater flow interacting with hydraulic routing of streamflow in complex open-channel (or stream) networks containing junctions and a variety of hydraulic structures. These structures include spillways, culverts, weirs and pump stations, as well as on-line and off-line reservoirs. The development of MODNET considered a number of technical linkage issues, and was verified with two numerical tests.

An analytical model is presented for predicting how rigid streambank vegetation effects the depth-averaged velocity at any point in a channel. The model was developed in conjunction with a study on the influence of black willow (Salix nigra) cuttings that were planted in 1994 along Harland Creek in Holmes County, MS, as part of an experimental bank stabilization project. A physical model study was performed in a 1.5-m-wide flume with a half-trapezoid shaped test section. Simulated willow cuttings (6.4-mm-diameter dowels) were arranged in four configurations and tests were performed for flow depths ranging from 23 to 38 cm, and discharges ranging from 22 to 113 1/s. Results from the physical model study were used to calibrate and verify the analytical model. Depth averaged velocities amid the simulated willow posts (6.4-mm-diameter dowels) were reduced by more than 50%. Predicted depth-averaged velocities amid the simulated willow posts were within 2%, on average, of the measured velocities when no model assumptions were violated. Insight gained from this study is used to make recommendations for improving the effective use of planted vegetation for bank stabilization, or bioengineering.

The so-called hydraulic routing methods incorporate both continuity and momentum-conservation equations to describe the configuration of a flood wave through a river reach. These may be very complex numerical schemes requiring, in most cases, a substantial amount of field data. Alternatively and due to their simplicity, the so-called hydrologic routing methods have been extensively used by engineers. These, such as the Muskingum method, employ only the continuity equation and a linear relationship between river storage and inflow/outflow discharges. Recently, optimization techniques, such as the genetic algorithm, have been used in order to identify the parameters of a flow routing model, which may include a non-linear relationship between river storage and inflow/outflow discharges, though keeping the general simplicity of the hydrologic routing methods. Genetic algorithms use reproduction schemes similar to those occurring in natural genetics to find solutions to a variety of mathematical problems. In the case of flow routing, the problem is one of error minimization. This flow routing model is applied to the São Francisco river basin, located in Southeastern Brazil. The case study has been selected to reflect flow conditions which may be considered appropriate for Muskingum-like routing methods.

HEC software packages are developed for use by Corps of Engineers offices engaged in water resources management activities and are made available to others via public domain distribution. The software are widely used by other federal, state, and local government agencies, private consultants, and international institutions. In recent years, HEC has been actively modernizing and replacing a number of its major software packages by taking advantage of advances in engineering and planning technology, and developing new source code using contemporary computer science concepts targeted at prevailing desktop computing environments. The modernization effort has thus far delivered the following: in river hydraulics, HEC-RAS successor to HEC-2; in watershed hydrology, HEC-HMS successor to HEC-1; and in flood damage analysis, HEC-FDA successor to the suite of flood damage programs (EAD, SID, etc.). In the reservoir system analysis area, the project will soon deliver the HEC-RSS family of programs, successors to HEC-3 and HEC-5. New releases began in 1995 (HEC-RAS was first) and continue to the present, with new releases or updates for all packages occurring in calendar year 2000 — HEC RAS Version 3.0, HEC-HMS Version 2.0, HEC-FDA Version 2.0, and HEC- RSS Version 1.0. Along the way, several new adjuncts and major utilities to these software packages have been developed; for example, GIS utilities HEC-GeoRAS and HEC-GeoHMS. This paper summarizes HEC software activities and provides an overview of the new package capabilities.

The Hydrologic Engineering Center (HEC) has added Unsteady Flow Routing capabilities to our river hydraulics software, HEC-RAS. The unsteady flow equation solver used in HEC-RAS is the UNET program, developed by Dr. Robert Barkau. HEC has developed a new geometry pre-processor for UNET that is based on the same hydraulic calculations that are used in the steady flow computations of HEC-RAS. This allows the user to enter data one time and perform either steady flow and/or unsteady flow analyses. Additionally, a post processor has been developed that takes the unsteady flow results and back calculates all the hydraulic properties that are available from the steady flow hydraulics. This allows the user to view the same types of output whether they run a steady flow or an unsteady flow solution. This paper presents the capabilities that have been added to HEC-RAS for performing unsteady flow computations. The unsteady flow pre-processor, hydraulic computations, post processor, and new output graphics and tables are described.

The Hydrologic Engineering Center (HEC) is developing high-end computer software for performing comprehensive flood impact analyses for watershed studies. The program, Flood Damage Analysis Version 2.0, merges the HEC's Flood Damage Analysis (FDA) Version 1.0 with the HEC's Flood Impact Analysis (FIA) Version 1.0 into a powerful new program. It uses discharge exceedance probabilities to formulate and evaluate flood damage reduction measures with risk-based analysis approaches. FDA Version 2.0 also uses single or sequential hydrologic events to evaluate flood impacts. The new program adds capabilities for user interactive analysis and displays using spatially referenced data. It is scheduled for completion and release in the fall of 2000. The release will include a user's manual and other documentation as appropriate.

The Hydrologic Modeling System (HEC-HMS) is "next generation" software for precipitation-runoff simulation that will supercede the HEC-1 Flood Hydrograph Package. The program is a significant advancement over HEC-1 in terms of both hydrologic engineering and computer science. This paper discusses current capabilities of the program that are not found in HEC-1. Future development plans and research topics are also discussed.

The Illinois River, one of the major tributaries to the Mississippi River in the Central United States, has a drainage area of 75,156 square kilometers (28,906 square miles) that covers portions of Illinois, Indiana, and Wisconsin. Except for about a 10,360 square kilometers (4,000 square miles) area in Indiana and Wisconsin, the Illinois River watershed is located within the state of Illinois. As a result of repeated leveling by glaciers, most of the Illinois River watershed is flat and covered with fine loess soil, making it one of the best agricultural regions in North America. More than 80 percent of the Illinois River basin is presently used for agricultural purposes. Most of the significant rivers in the state such as the DesPlaines, Fox, Kankakee, DuPage, Vermillion, Mackinaw, Spoon, Sangamon, and LaMoine Rivers all drain into the Illinois River. Restoration of the Illinois River will require proper understanding of the natural factors and how human-induced changes that control the hydrology of the watershed and the hydraulics of the river over time. This paper summarizes the historical changes that have affected the hydrology and hydraulics of the Illinois River basin and evaluate their influence on restoration efforts in the future.

Peoria Lake, located at River Mile 157-179 on the Illinois River, is the largest bottomland lake on the Illinois River. This lake extends for about 35 km within the Peoria pool of the Illinois River. Geologically, the lake was formed by the constriction exerted by tributary deltas which flooded the broad, wide, and shallow floodplains. In 1939, Peoria lock and dam was constructed to aid in the commercial navigation especially during low flow periods. Over the years, Peoria Lake lost more than 80 percent of its original capacity due to sediment deposition. Research conducted has shown that as much as 50 percent of the sediment could be contributed by the local bluff tributaries draining about 4 percent of the total drainage area of the lake. One of the most promising alternatives for the revitalization of Peoria Lake is to remove the deposited sediments by dredging and utilizing the same sediments to build artificial islands within the lake. In order to test the viability of such an alternative, two-dimensional unsteady SMS has been calibrated and verified for the entire 35 km reach of the river. Alternatives such as artificial islands of various shapes and sizes with associated deep water channels are being tested to determine the feasibility of constructing such artificial islands with dredged materials and maintaining the dredged channel(s) as deep water habitats. It is suspected that one or two islands with dredged materials may be built in the near future within the channel border area of Peoria Lake. This paper presents some of the results of the hydrodynamic modeling work for this specific project.

The Illinois River is a major tributary river of the Upper Mississippi River System. The system is designated a nationally significant ecosystem by the Water Resources Development Act of 1986 which mandated that the rivers be managed to balance competing interested in this natural resources. A wide variety and number of migratory birds, as many as 285 species of birds, are likely to be found in this area use the Illinois River valley. Degradation of the ecosystem comes from many sources that include hydrological processes, flooding, strip mining practices, runoff, sediment transport and deposition, and diminished nutrient cycles. Two Corps of Engineers' Studies: the Peoria Riverfront Development study and the Illinois River Ecosystem Restoration study will evaluate components of the State of Illinois' Integrated Management Plan and address aspects of the degradation of the Illinois River Ecosystem. Environmental restoration activities could include limited stream restoration, wetland creation, wildlife restoration, and surface restoration, recommendations for maintaining viable populations of native species, and other engineering solutions to environmental problems in the watershed. A holistic review of ecosystem management practices will be conducted in a partnership with state and Federal agencies to restore fish and wildlife habitat and in the development of a system-wide management plan. Particular emphasis will be place on restoration of wetlands, neotropical migrants, Federal and state significant species, and protection of floodplains and floodways for fish and wildlife enhancement. The Peoria study began in calendar year 1999 and the Illinois River Ecosystem Restoration study will begin in the year 2000.

The Illinois Department of Natural Resources is investigating techniques for removing sediment and using it beneficially. Numerous sediment cores, including ten extending two meters, were analyzed for a variety of metals and chemicals as well as agricultural nutrients. Plant germination and growth tests comparing fresh and weathered sediment to Illinois topsoil were conducted in a greenhouse. A hydrodynamic model of a portion of the river was developed to assist in predicting the effects of sediment removal and placement. A number of options to remove sediment at near insitu moisture content are under consideration including high solids pumps, excavators, clamshells and conveyors. This would minimize turbidity, resuspension and dewatering while maximizing options for sediment transport and placement. Researchers are looking at sites where dredged material was placed in the past to determine the qualities of soil formed by fine-grained sediment similar to that in the Illinois River. It is hoped that sediment will prove useful as a landscaping soil, soil amendment, brownfield cover and for strip mine reclamation. Additionally sediment may be used to create islands and floodplain habitat that is similar in elevation and geometry to that which existed prior to the major hydrologic changes that occurred beginning in 1900.

Low Impact Development (LID) is an innovative micro-scale runoff control strategy for WWF management issues. This technology is based on a combined strategy of conservation to reduce hydrologic impacts and the incorporation of distributed micro-scale Best Management Practices (BMP's) throughout the subcatchment. This site-based approach has a goal of maintaining the pre-development hydrologic regime of the project site. Because this is a volume-based approach to management of runoff, there is great potential to reduce the runoff volume, sediment loads, and floatables that can reach receiving waters. In order to fully understand the effects of reduced runoff volume and timing, as well as the full implementation of this technology within the catchment, modifications to existing models and new models must be developed. This paper will explore the potential and limitations of existing models to evaluate the effectiveness of this design approach.

A conceptual framework is presented that incorporates disparate information to determine the impacts to receiving waters. The framework is then applied using actual data from various subwatersheds in Baltimore County, Maryland to evaluate the respective significance of the input data at determining the objectives and goals for each receiving water and to design the process for developing watershed management plans. Using an established framework, such as presented here, provides the watershed managers with a defensible tool for characterizing and classifying receiving waters. It then guides the managers on the types and detail of the data needed during subsequent stages to identify, screen and select measures for mitigating existing receiving water impacts and managing potential future impacts. The framework incorporates information such as ecological, physical, water quality and Geographic Information System planimetric data, as well as existing land uses and proposed conditions. While land use practices govern the change in storm water runoff characteristics, the resultant impact to receiving streams differs. Studies in the Mid-Atlantic region, and nationwide, have indicated that local variables such as the sensitivity of the ecology and geomorphology interact with the degree of development, land use practices and existing management practices to create a broad range of impacts to receiving waters. The framework establishes a flow chart approach using metrics for evaluating the relative impacts to the receiving waters and deterring the causes.

This research examined a common, but poorly understood, problem associated with land development, namely the modifications made to soil structure and the associated reduced rainfall infiltration and increased runoff. More than 150 infiltration tests were conducted in disturbed urban soils and the data was compared with the site conditions. A complete factorial experiment fully examined the effects, and interactions, of soil texture, soil moisture, and compaction. Age since development was also briefly examined. The major finding was that compaction had dramatic effects on infiltration rates through sandy soils, while compaction was generally just as important as soil moisture at sites with predominately clay rich soils. Moisture levels had little effect on infiltration rates at sandy sites. Because of the large amounts of variability in the infiltration rates found, it is important that engineers obtain local data to estimate the infiltration rates associated with local development practices.

Low Impact Development (LID) is rapidly being recognized as an ecologically sustainable and cost effective strategy to protect receiving waters from the water quality, volume, magnitude, and frequency effects of stormwater runoff. The LID strategy is based on creating hydrologically functional equivalent design features that replicate the pre-development conditions through the use of pollution prevention, precision engineering, and integrated micro-scale Best Management Practices (BMPs) that are distributed at a landscape level throughout a site. The use of this approach is rapidly gaining acceptance in suburban and developing areas. The use of micro-scale approaches in urban areas is limited in this country, although it has been successfully employed in many areas of Europe for a significant period of time. This paper presents the management strategies, protocols, and technological approaches that will incorporated in the development of an LID management strategy for the control of WWF in urban areas. This project is being funded by a grant through USEPA Region 3 and Office of Water and is being coordinated with other recent urban LID efforts that are currently taking place in the Washington, D.C. area.

Through the use of funding from the National Science Foundation, this project involved developing interdisciplinary hydrology laboratories at all undergraduate levels. Equipment was purchased that recorded weather and groundwater data that could be collected at a field site, downloaded to a computer system, and accessed by the students. In some classes, field trips to the site were conducted so students could get a better feel for the instruments collecting the data. In other classes, however, the information was simply presented to the students. Classes ranged from an introductory Geology 101 laboratory to a senior level Civil Engineering 460 advanced hydrology course. Two basic units were created: (1) Surface Water and (2) Ground Water and Geochemistry. A web site is being created so that other universities can access the data and course outlines to see how the information can be incorporated into their classes.

The Red River Basin has a long history of documented major flooding beginning in 1824 with the initial settlement of the Basin. In 1955, the Minnesota legislature authorized the formation of watershed districts based on tributary watershed boundaries to manage water in a holistic manner. Eleven districts were formed in the Red River Basin and by 1992, the watershed districts in the Red River Basin had constructed 35 water control structures.

Cost-effective sampling (CES) is a methodology for reviewing and assessing ground water data. The CES program produces a data information sheet and a lowest-frequency sampling schedule for a given groundwater monitoring location that provides the needed information for regulatory and remedial decision-making. The determination of sampling frequency for a given location is based on trend, variability, and magnitude statistics describing the contaminants at that location. The underlying principle is that a location's schedule should be primarily determined by the rate of change in concentrations that have been observed there in the recent past. The higher the rate of change, whether upward or downward, the greater the need for frequent sampling. Conversely, where little change is observed, a more relaxed schedule can be followed. CES was implemented at LLNL in 1992 and approved by U.S. EPA - Region IX and the local regulators. Applying the CES methodology has produced a 40% reduction in the required annual number of routine ground water samples at LLNL. This reduction has saved LLNL $390,000 annually in sampling, data management, and analysis costs.

Long term monitoring and operations comprise a substantial and growing part of the present value cost of groundwater and soil cleanup systems. These burgeoning costs at groundwater cleanup sites present a significant opportunity for the use of optimization. Numerous optimization technologies have been researched and developed over the past two decades. These have been used to suggest ways to operate pump-and-treat remediation systems at effectively reduced costs. Contemporaneously, characterization methods based on kriging methods, artificial neural networks and Extended Kalman Filtering have been developed and deployed. In addition to mapping property values, the characterization methods detect and describe (spatial and temporal) correlations among aquifer properties, and are used in uncertainty assessments. These technologies are reusable and form the core of an Adaptive Long Term Monitoring and Operations System (aLTMOs) to assess and optimize long term monitoring network performance and costs. A preliminary application of the optimization system to the Army SSCOM in Massachusetts is presented.

The US EPA Superfund program is starting a major shift in its direction. Superfund's main emphasis will no longer be investigating and determining remedies for abandoned hazardous waste site. The majority of abandoned hazardous waste sites have been cleaned up. Most cleanups involving groundwater have long-term remedies. Superfund is required to maintain and assure hundreds of long-term post construction remedies involving groundwater, are still protective. The new thrust for the Superfund program will consist of three main objectives. Superfund will continuously be ensuring all site remediations are meeting clean up objectives. Superfund will continuously be optimizing the remediation for effectiveness and cost. Superfund will be facilitating the site cleanup, in order to achieve shutdown of the site remediation at the early possible date. Many of the new problems Superfund now faces have been solved at the University level. However, there is lack of off-the-shelf tools that can be used by the general practitioner. Some areas that are in need of these tools will be presented.

The 1997 flood of the Red River between Grand Forks, North Dakota and Winnipeg Manitoba referred to by many as the "flood of the century", tested the existing flood protection infrastructure to the limits. The risk of a similar or greater flood event has stimulated numerous activities. One activity is the commissioning of the Canadian virtual database by the International Joint Committee Red River Task Force (IJC). The Canadian Red River Basin flood management Virtual DataBase (RRBVDB) is a component of the Red River Basin Disaster Information Network (RRBDIN currently being developed by the US government. The RRBVDB virtual database concept can best be described as a gateway to data repositories that reside in several locations, making them accessible via the Internet. The RRBVDB focuses on providing access to data sets that relate to flood management activities within the Red River Basin. These activities consist of flood fighting efforts, but also flood planning and flood recovery activities. As a virtual data repository or clearinghouse, the RRBVDB provides access to data that is maintained by various Canadian agencies. However, developing a data clearinghouse does not quite fit the full intent of the RRBVDB. The final goal for future development relates more as a decision support tool in which specific activities and decision processes are directly supported. This paper presents the initial phase of RRBVDB development and its link with related disaster management activities throughout the basin. The content of the paper consists of a description of the overall vision for providing flood disaster decision support, a discussion of the approach for integrating various Canadian data providers within the current "Canadian data culture" and a tour of the current functionality.

Information is the principal resource of almost any government agency, and that is particularly true with agencies involved in floodplain management. Problems caused by the inaccessibility, incompleteness, inaccuracy, or untimeliness of the information can severely limit flood management personnel in meeting their objectives in the most productive and effective manner. In the aftermath of the Red River of the North (RRN) flood of 1997, the governments of Canada and the United States agreed that steps should be taken to reduce the impact of future flooding. They asked the International Joint Commission to analyze the cause and effects of the 1997 flood and to recommend ways to reduce the impact of future floods, including a relevant information base for the basin. An International Red River Basin Task Force (Task Force) was formed to conduct this work. The Task Force recommendation to devise strategies to effectively integrate and manage disparate data and information types parallels the vision of the Global Disaster Information Network (GDIN). GDIN is a multi-agency initiative within the U.S. to promote cooperation between user and provider interests in support to disaster management. To reach that goal the Task Force has been working to devise a strategy to identify an information infrastructure for the area of interest, to promote this concept within the broadest possible stakeholder community, and to make recommendations for a sustainable virtual presence. In July 1998, the Task Force conducted a series of workshops in Minnesota, North Dakota, and Winnipeg, Manitoba. A broad spectrum of stakeholders clearly articulated unmet needs in information and data availability, management, and the need for sustaining information infrastructure to improve emergency response and floodplain management. The process for generating local input for the information needs assessment as well as the results will be discussed.

The Red River Basin Disaster Information Network (RRBDIN) is being developed to promote the use of collaborative information technologies in support of floodplain management practices within the Red River Basin. The goal is to create a sustainable, web-based presence that is relevant to a broad range of interests - from local residents to raw data providers. The RRBDIN web site has been developed under joint sponsorship from the International Joint Commission and the Global Disaster Information Network. Local constituents who participated in workshops that were held within the Basin following the 1997 Flood made it clear that sustainable access to relevant data and information was critically needed. The effectiveness and efficiency of an Internet-based system that could provide users with a means to obtain necessary data and the ability to use decision making tools for floodplain management, disaster relief and mitigation is being developed and tested as part of this developmental effort. Particularly important is the ability of such a system to deliver information during a real emergency. It is anticipated that this approach will provide an interactive and iterative process for building basin-wide information resources that specifically addresses improved communications and enhanced cooperative opportunities.

To achieve more accurate flood damage estimates in the Red River Valley, the development of a stage-damage model needs to consider the spatial and temporal impact of flooding. KGS Group was contracted by the International Joint Commission to perform a study that would update existing stage-damage (depth-damage) relationships and incorporate them into a methodology to map potential flood damages in the Red River Valley resulting from a repeat 1997 and 1826 flood event. The development of updated depth-damage relationships, and the various data sources were compiled through the use of a GIS and database model. The GIS/Data model computes structural damages by relating damage to the depth of flooding at the first floor while considering existing flood protection infrastructure. Damages to civil infrastructure were computed by relating the density of infrastructure works (primarily roads) within the flooded area to a damage function developed from reported damages. Agricultural losses are calculated based on the expected crop yield reductions resulting from a delay in seeding.

Several researchers have shown that the traditional historical weighting procedure described in Bulletin 17B is inefficient and can not fully utilize many types of historical and paleoflood data. The Expected Moments Algorithm (EMA) is a new, simple and efficient method for incorporating historical and paleoflood information in flood frequency analysis. EMA has been shown to be a theoretical and practical improvement over the Bulletin 17B historical method. A computer program called EMFREQ was developed to implement EMA for usage and testing by practitioners. The program is used for flood frequency estimation that includes historical and/or paleohydrologic data. The purpose of this paper is to communicate the EMFREQ computer program to the water-resources community. The purpose of the program, input data requirements, and computational procedures are briefly described. EMFREQ performance is shown for two examples.

The Morefield mound of Mesa Verde National Park (MVNP), long a park enigma, was proven to have been a water storage reservoir operated by early Americans from A.D. 750 to 1100. The pre-historic inhabitants of Mesa Verde deserve much credit for their ability to construct and maintain a public works project over a 350-year period under harsh conditions.

This paper illustrates the value of historical flood and paleoflood information when flood frequency analysis is performed in partial duration series (PDS) and annual maximum series (AMS) frameworks. The PDS analysis considers the Generalized Pareto distribution for exceedances over a threshold with the Poisson arrival model. This corresponds to a 3-parameter Generalized Extreme Value (GEV) distribution in a AMS framework. The simple relationship between the two models is quite convenient. When the shape parameter is set to zero (2-parameter models), one obtains the exponential/Poisson model for the PDS, and the Gumbel distribution for the AMS framework. The value of historical information with partial duration series and annual maximum series data is explored using the relatively new Generalized Maximum Likelihood estimators (GMLEs). Historical flood information can be of tremendous value depending on the magnitude of the perception threshold for the historical and paleoflood information, and the length of the historical record length.

In 1950 when Cherry Creek dam, which is located in Denver, Colorado, was completed, the design flood was 5,126 m³/s. Two recent probable maximum flood (PMF) estimates for the dam range from 14,840 to 18,750 m³/s demonstrate the uncertainty in estimating extreme flooding in eastern Colorado, PMF difference is due in part to a lack of extreme rainfall and flood data in eastern Colorado. A paleoflood study was conducted to assist dam-safety officials in assessing the risk of large floods in Cherry Creek basin. An envelope curve encompassing maximum contemporary floods (19 sites) and paleofloods (99 sites) was developed for Cherry Creek basin streams; paleoflood data reflect maximum flooding during the last few hundred to many thousands of years. Maximum paleofloods in Cherry Creek range from about 1,050 m³/s near Franktown (in about 5,000 to at least 10,000 years), about 2,100 m³/s near Melvin (in about 1,500 to 5,000 years), and about 2,270 m³/s at Cherry Creek Reservoir (also in about 1,500 to 5,000 years). Flood-frequency relations for Cherry Creek, which incorporate paleoflood data, indicate the 10,000-year flood (10⁻⁴ annual exceedence probability) ranges from about 1,200 m³/s (near Franktown) to about 2,200 m³/s (near Melvin). PMF estimates are about six to eight times larger than paleofloods in Cherry Creek basin. Additional research in flood hydrometeorology is needed to help dam safety officials evaluate potential safety problems related to large floods in Cherry Creek basin.

The Environmental and Water Resources Institute (EWRI) Technical Committee on Surface Water Hydrology is sponsoring a Task Committee on Paleoflood Hydrology to prepare a monograph entitled, "Use of Paleoflood and Historical Data in Water Resources Applications." This paper introduces the subject of paleoflood hydrology and discusses the topics, which are expected to be included in the monograph. The procedure for preparing and reviewing the monograph will also be discussed. The paleoflood hydrology monograph will include a discussion of types of hydrologic and paleoflood data, paleostage indicators, flood chronology, modeling methods, interpretation issues, water resources applications and case studies, and research needs. Paleoflood data collection and analysis techniques will be presented, and various applications in water-resources investigations will be provided. An overview of several flood frequency analysis approaches, which consider historical and paleoflood data along with systematic streamflow records, will be presented. The monograph is scheduled for completion and publication in 2001.

As we enter the new millennium, water districts, municipalities, and private utilities must deal with expanding governmental/regulatory agencies in order to construct new facilities. In addition, third parties such as homeowners associations, historical societies, and local businesses are becoming more involved in their communities and interested in local construction projects. In order to gain acceptance of their project and achieve a win/win solution, the Contra Costa Water District (CCWD) took a partnering approach with project stakeholders. CCWD implemented this approach during planning and design and throughout construction, contributing to a very successful project. This paper describes the partnering process useful for the CCWd's Port Chicago Pipeline Project and discusses the lessons learned that may help others facing similar issues.

Bushkill Creek is a small tributary of the Delaware River, draining a 200- km² watershed and discharging to the river at the town of Easton, Pennsylvania. Land use on the upper half of the watershed is largely agricultural and sparse residential, but on the lower half is rapidly expanding suburban/commercial development. The watershed has been the focus of various water quality investigations over the past 30 years, including ongoing data collection by local high school and college students. Although its lower reach has a long history of industrial use, the creek supports a high quality trout fishery, and includes an environmental education center operated by the state Department of Conservation and Natural Resources (DCNR). The Bushkill Stream Conservancy is also active in a variety of environmental concerns in the watershed. Local planning offices have conducted a coordinated stormwater runoff modeling study in compliance with the Pennsylvania Stormwater Management Act (SWMA), and the watershed is located in one of the few counties with a state-approved stormwater management plan.

Estimating ecosystem impacts from alternative water management policies or practices involves an understanding of both engineering and biology, among other disciplines. However, the modeling approaches used by biologists and engineers to estimate these impacts are usually quite different. Engineers commonly use the Eulerian modeling framework to simulate bulk water flow and the biological, chemical and physical processes that affect lower trophic levels of ecosystems, such as bacteria, algae and protozoa. In contrast, biologists typically use an implicit Lagrangian modeling framework to simulate population dynamics or the influences of competitors, predators, and resource availability on populations of higher trophic levels, such as fish. These two modeling frameworks can be coupled together into a comprehensive coupled Eulerian-Lagrangian hybrid (CEL Hybrid) model to predict the interactions within, and the effects of water resources activities on, a wider range of ecosystem trophic levels than can either framework by itself. Our CEL Hybrid models use stimuli-response rules to transform neutrally buoyant objects into ‘smart' objects, or virtual organisms, emulating the movement behavior of individuals of an aquatic species in a simulated hydraulic and/or water quality environment. Standard calibration techniques are used to achieve movement behaviors in the virtual organisms that best emulate the movements of observed species. Once the movement behaviors of a higher trophic species are incorporated within a CEL Hybrid model, the model can be used to estimate the impacts of any water resources management activity on species population processes at any one of a number of trophic levels and spatial and temporal scales.

Bangladesh is inhabited by about 125 million people in an area of about 147,000 square kilometer and is located within the floodplains of three great rivers of the world: the Ganges, the Brahmaputra and the Meghna. About 93% of the catchments of the country's river system lie outside in the upper region of Bangladesh, but drain the system over its floodplains to the Bay of Bengal. Because of this unique geographic location, the country suffers heavily due to flooding almost every year. Conservative estimates put the damage due to floods in Bangladesh to about 200 million US dollars every year on an average in terms of damages to crops and properties. As a result large number of flood control and drainage (FCD) schemes have been built in Bangladesh in the past. These schemes were built by "top down" management that neglected the poor. People were not consulted during identification, planning and implementation of these projects and were operated and maintained by public initiatives without considering needs and aspiration of the people. The water control systems were operated as desired by landlords of the project area, and the marginal and small farmers were not consulted. The maintenance of the completed system with public revenue budget could not be continued for long due to resource constraints, and as a result many of the infrastructure deteriorated and lost their functional ability. In fact a good number of FCD schemes have been out of operation for long, created negative impact on aquatic environment and people wanted their demolition to restore natural condition.

The field of watershed management is a rapidly evolving area in which the participants are recognizing that sound tools for managing people and institutions are just as important as the tools for managing the technical aspects of a problem. In fact, the call for abstracts for this conference acknowledged: "It is more important than ever to ensure that the best possible management, information and technology options are being implemented." The Los Angeles and San Gabriel Rivers Watershed Council has developed a comprehensive vision statement which describes how the watershed will look in the future because they believe it is a critical step in their ability to manage the watershed. A wide variety of stakeholders all agreed that a clear picture of where they were going was paramount if their efforts were to be successful. This paper describes the history of the Council, its membership, the process they went through to develop their vision, and the steps they've taken towards implementation. It emphasizes the importance of the Council's role as a facilitator of multiple stakeholders within the watershed, rather than the creation of a new organization. It describes the critical role that regular Council meetings play in developing trust among stakeholders, educating stakeholders from a wide political and technical background about technical issues, and building champions within governmental and other organizations about the need for watershed management. It stresses the need for consideration of management tools such as consensus building, teamwork, and conflict resolution, as well as good old-fashioned patience and long-term commitment from individual's as well as organizations.

Ship Operation on Inland Waterways induces dynamic loads on slopes and beds of natural and artificial Waterways, depending on Geometry of the Waterway, bed's armor, Speed and draught of the Inland Vessel. This might endanger stability of bed and bulkheads limiting Artificial Waterways. To determine propeller-induced current velocities, scour and erosion phenomena on Waterways empirical approaches and equations still do not provide satisfying results. Especially the influence of current deflections by the ship's rudder angle is not quantified yet. Therefore, Physical Model Tests were executed with a model of an Inland Vessel in a scale of 1:16 aiming at measurement of propeller-induced current velocities. The Inland Vessel was equipped with a 4-bladed Propeller and an adjustable rudder. The tests were carried out in a fixed bed model. To exclude effects of reverse current velocities below the ship due to ships drive with might reduce the propeller's effects, the ship was fixed to the flume, varying the rotation speed of the propeller from 600-900 rpm and modifying the rudder angle from 0° − 45°.

Local sediment scour experiments have been conducted with 0.114 m, 0.305 m and 0.914 m diameter circular piles in a 6.1 m (20 ft) wide by 6.4 m (21 ft) deep by 38.4 m (126 ft) long flume in the Hydraulics Laboratory at the USGS Conte Laboratory in Turners Falls, MA. All of the tests to date have been in the clearwater scour range of velocities and with two near uniform diameter sediments with median diameters of 0.2 mm and 0.8 mm. All tests were conducted with steady, fully developed flows. This paper describes the procedures and instrumentation used in these tests and outlines the live bed scour experiments that are planned after the completion of the clearwater tests.

Physical models are used in many areas of engineering to obtain information about prototype situations. Ideally, the important dimensionless groups for the problem being examined are made the same for the model and prototype. When this is possible there is no question about the relationship between the quantities being measured in the model and their corresponding values in the prototype. There are, however, situations where all of the important parameters cannot be maintained constant and this creates a problem when estimating values for the prototype from measured values in the model. In modeling local scour at bridge piers such a problem is encountered when the prototype sediment is sufficiently small that it cannot be scaled using the geometric scale for the model. This paper presents a method for scaling measured local scour depths in physical model tests to prototype conditions based on scour prediction equations developed by the lead author. The method is demonstrated using data from laboratory tests conducted with circular piles ranging in diameter from 0.114 m to 0.914 m.

The Woodrow Wilson Bridge on I-495 over the Potomac River in Prince Georges County, Maryland is being replaced. Physical local scour model studies for the proposed piers for the new bridge were performed in order to help establish design scour depths. Tests were conducted in two different flumes, one in the USGS-BRD Conte Research Center in Turners Falls, Massachusetts and one in the FHWA Turner Fairbanks Laboratory in McLean, Virginia. Due to space limitations in this publication only the tests conducted in the USGS flume are presented in this paper. Two different pier designs were tested. One of the piers was also tested with two different diameter dolphin systems.

The only underwater international vehicular (automobile) tunnel in the world owes its existence to Fred W. Martin, a Windsor, Ontario Salvation Army Captain who said he was "inspired by God" to have the tunnel under the Detroit River built. It was not God, however, but the New York City engineering firm Parsons, Klapp, Brinckerhoff and Douglas (designers and builders of the Holland Tunnel in New York) who Martin visited one day in 1926 to see if such a tunnel could be built and operated profitably. Confident that the project was indeed feasible, and with urging from Martin who suggested that "it would probably be six dozen Sundays or more before the politicians would agree on anything, so how about taking a flyer on this as a private project?" the engineers not only agreed to design the tunnel but to guarantee its costs. The privately-financed, privately-built, and privately-operated 2.4 km (1.5 mi) tunnel connecting Detroit. Michigan and Windsor was completed in 1930 after 26 months of construction, and to this day is a major border crossing and a vital socio-economic link between the United States and Canada.

When dealing with a project storm in the design of flash flood control works and related structures in areas subjected to convective storms, it is necessary (mainly for economic and safety conditions) to simulate, the best as possible, the actual natural situation of the precipitation. It is important not only to reflect the temporal and spatial variations of the rainfall fields (as it is reflected in the project storm) but also the uncertainties in these variations, the "maximum possible" number of simultaneous cells that impact the basin, the prevalent path and the frequency of thunderstorm hits, mainly for big basins with many subbasins. Each thunderstorm cloud consists of a number of convective cells that actually may produce rainfall and possible runoff. Furthermore in mountain areas the frequency of an intense convective precipitation (flash-flood producing storms) varies with the elevation of the terrain. With the use of "ground true" precipitation data from a dense telemetric network and historical radar information, a "realistic" design of flash-flood control works was performed.

The operation of reservoirs in the Sierra Nevada Mountains of California for flood control relies on forecasts of reservoir inflows. In the past, accurate forecasts of the reservoir inflows resulting from watershed runoff have been made, but only after the water had entered the main channel. During flooding events, this limits the amount of time available for the implementation of emergency management procedures. Translating precipitation forecasts into runoff forecasts can greatly improve the runoff-forecast lead-time. The operational NCEP Eta model provides 48 hour-ahead forecasting of precipitation in 6-hour intervals in a 40-km by 40-km gridded form. In this study, in order to link the Eta model precipitation forecast results to the watershed model, HEC-HMS, for runoff prediction, the mesoscale model, MM5, is used to transfer the Eta forecast data down to the appropriate space and time scales. An initial diagnostic study of this procedure has been implemented on the Calaveras River watershed in Central California. This paper presents the study results along with a discussion of the methodology and future directions.

An active 1999 hurricane season brought several significant hurricanes, tropical storms, and other heavy rainfall events to the Florida Peninsula. During this period, high-resolution gage-adjusted radar-rainfall estimates were developed for the entire state. Radar-rainfall estimates from a mosaic of overlapping radar coverages in Florida were combined with local rain gages from northeastern Florida to create a composite data set of gage-adjusted radar-rainfall estimates on a 2 km x 2 km grid every 15 minutes. This paper presents comparisons between gage measurements and the resulting radar estimates. The results will focus on a 12,400 square mile area in northeastern Florida containing 97 rain gages.

Flooding conditions along the Texas Gulf Coast and in the Houston area have increased significantly over the past thirty years due to a drastic increase in urbanization. Two urban watersheds, the Brays Bayou watershed and the White Oak Bayou watershed, are both channelized streams that cannot contain their current 100-year design storm and are now subject to flooding during small storms. Highly spatially and temporally variable rainfalls are common in the area. Level II reflectivity data from the WSR-88D NEXRAD radar was used to estimate rainfall rates over both watersheds for two storms (October 1994 and September 1998). The hydrologic modeling results from variable grid size radar-rainfall inputs (1 km², 4 km², and 16 km²) were compared to the results of the hydrologic modeling using the traditional method of Thiessen polygon weighting from the local rain gages. All modeling studies were compared to the observed flows at a downstream flow gage. Hydrologic modeling runs using radar-rainfall have been very encouraging and were used to create the real-time hydrologic forecasting capabilities of the Rice University - Texas Medical Center Flood Alert System (www.floodalert.org). The system, in place since 1998, serves the largest medical center in the world and uses WSR-88D rainfall averaged over the entire basin to make flood forecasts.

Storm rainfall often cause considerable material damage and human losses. In order to mitigate such disasters, the design of hydraulic structures and flood plain occupation planning must take into account the risks associated with the occurrence of heavy storms. These risks are estimated by statistical analysis of temporal series of recording raingauge data, from which the intensity and duration of events can be estimated. This paper is a summary of an extensive study aiming to estimate regional intensity-duration-frequency (IDF) curves for the Brazilian state of Rio de Janeiro. Such a study has been motivated by recent episodes of extensive damages caused by heavy storms in the state of Rio de Janeiro and by realizing that the last state-wide statistical study has been carried out in the late fifties; the quality of that previous study has been limited by the number of recording raingauge stations available at the time. The present study has been carried out with partial duration series abstracted from data recorded at 34 raingauge stations, spread throughout the state's territory. In addition to this expressive volume of data, contemporary methodologies of regional analysis, based on the so-called L-Moments, have improved parameter and quantile estimates of extreme rainfall intensities. By defining homogeneous regions over the state of Rio de Janeiro and taking into account local characteristics, the IDF curves are estimated for each region, from which one can define quantiles for designing hydraulic structures and stormwater drainage systems.

In this paper, the properties of time scale invariance of rainfall are investigated and applied to intensity-duration-frequency relationships. The hypothesis of simple scaling implies in direct and empirically-verifiable relations among the moments of several orders and also among the probability distributions of rainfall intensities of different durations. Using these relations, it is possible to analitically derive IDF relationships for short-duration rainfall from the statistical characteristics of daily data only. The simple scaling model has been applied to precipitation data observed at the Vespasiano rainfall gaging station, located in the metropolitan region of Belo Horizonte, in southeastern Brazil; the results have been compared to those obtained by at-site IDF synthesis.

Due to the occurrence high-intensity rainfall events more frequently than expected, the Michigan Department of Transportation has deemed it necessary to Update the regional rainfall intensity-duration-frequency (IDF) estimates for the State. Rainfall intensity estimates are to be determined for each of seven durations (1, 2, 3, 6, 12, 18 and 24 hours) and six frequencies (0.5, 0.2, O.1, 0.04, 0.02. and 0.01 per year). Traditionally, method of moments or maximum likelihood procedures have been used to fit a suitable probability distribution to annual maximum or partial duration series data for each gage, and isopluvial maps have been developed from these site-specific IDF estimates using interpolation procedures and judgment. This paper discusses the application of a regional frequency analysis approach based on probability-weighted moments that promises to provide more objective and robust IDF estimates. Definition of homogeneous regions, selection of a distribution, and estimation of parameters are discussed.

For hydraulic design purposes, the Michigan Department of Transportation (MDOT) currently uses rainfall intensity-duration-frequency (IDF) estimates for four rainfall zones in Michigan. The delineation of these zones is based on frequency estimates at gage sites and isopluvial maps developed by interpolation procedures and subjective judgment. The objectives of this study are to apply more objective interpolation procedures to regional frequency estimates and to develop an interactive geographic information system (GIS) interface capable of querying and displaying location-specific IDF curves. For each of seven durations (1, 2, 3, 6, 12, 18, and 24 hours), and for each of six event frequencies (0.5, 0.2, O.1, 0.04, 0.02, 0.01 per year), a rainfall intensity grid will be developed using a spatial interpolation procedure available in a commercial geostatistical software package or GIS. An interactive model capable of querying and displaying location-specific rainfall IDF estimates will then be developed to manage the rainfall intensity grid. Through the GIS interface, users will be able to select a specific geographic location within the state of Michigan and display IDF curves and other related information for the selected location. This product will provide water resource professionals with a faster, easier-to-use tool for determining appropriate rainfall intensity values for use in hydrologic engineering design.

Good accuracy in snowmelt runoff analysis is needed for water resource management in snowy mountainous regions. In the present study, a distributed, as opposed to lumped, model of snowmelt calculation as well as runoff calculation is developed and applied to a mountainous basin in Japan with the catchment area of 355 km². In applying this model, observed temperature data are analyzed to obtain the actual lapse rate, which in turn gives the temperature distribution throughout the basin. For the distribution of snow precipitation the catch-ratio of the gage and dependence on the altitude is assumed and the associated constants are determined to give the best fit of the calculated runoff to the observed data. The result shows the better fitting with the runoff data as compared to the calculation without this kind of consideration.

Remotely sensed soil moisture measurements offer the ability to characterize antecedent moisture conditions at a basin scale. A GIS framework was used to develop and process land use soil type, and remotely sensed soil moisture data in order to improve estimates of runoff calculated using the U.S. Department of Agriculture (USDA) Curve Number method Recently developed algorithms for passive microwave airborne remotely sensed measurements were used to provide the soil moisture data at spatial scales necessary for watershed modeling applications. Data for this study are from a recent large-scale field experiment in the Little Washita Basin in Oklahoma. Empirical curve numbers for several sub-basins of the Little Washita Basin were determined using the soil type and land use data. For two storm events, these curve numbers were adjusted using the remotely sensed soil moisture data that was observed prior to the event. Both composite and distributed curve numbers were developed to determine the effect of aggregation on runoff estimates.

In the procedure proposed by Sherman and hence the standard procedure for unit hydrograph derivation, observed rainfall and corresponding runoff data are utilized to deduce the unit hydrograph for a specified rain duration. This is a lumped system approach without considering the physical flow process inside the watershed. It has long been found that for a given rain duration the unit hydrographs derived from different rainfalls are not the same; usually the more the rain the higher the peak. Often these different unit hydrographs are averaged or weighted and combined to yield a single graph which is regarded as the unit hydrograph for that rain duration. It is obvious that the relation between watershed rainfall (the input) and runoff (the output) is not a linear function. The nonlinearity can be observed through watershed hydrologic records or by investigating flow equations such as: Manning, Darcy-Weisbach or Saint-Venant, for depth and velocity or discharge. In this study, the kinematic-wave based geomorphic IUH model (KW-GIUH) proposed by Lee and Yen was adopted for simulating watershed runoff and demonstrating the nonlinearity of the rainfall-runoff processes. The watershed runoff-response function is expressed as a set of instantaneous unit hydrographs to account for different rainfall input conditions. Hydrologic records from two watersheds in Taiwan were used to demonstrate the nonlinearity of the runoff process, and used as examples to show the capability of the KW-GIUH model to handle the nonlinearity. It is hope that the improvement of accounting for the nonlinear effect will help to make the unit hydrograph theory to fulfill its promise.

The Estero-Imperial-Cocohatchee (EIC) watershed located along the southwest coast of Florida has in recent years experienced a number of severe floods. The watershed is characterized by small topographic gradients and the southwestern area of the watershed is a large swamp area. The agricultural and urban development in the area has changed the original flow paths and due to insufficient conveyance capacity and under sized hydraulic structures, water levels in the area rise during long continuous periods of rainfall and floods the cities. An integrated hydrological/hydraulic model is being developed for the watershed with the main objective of simulating flooding. The model is based on an integrated, distributed hydrological model (MIKE SHE) encompassing overland flow, unsaturated zone flow and groundwater flow dynamically coupled to a river hydraulics model (MIKE 11). Although primarily used for flooding purposes, on event basis, the modeling system is versatile and may be used for continuous simulation investigating water resources aspects and environmental impact assessment on wetlands, e.g. Corkscrew Swamp. Compared to traditional flood models the integrated approach provides a physical representation of the flow processes rather than lumped rainfall-runoff modeling. In the EIC watershed with slowly increasing water levels the response of the entire hydrological system will affect the critical flood levels. The integrated model offers better possibilities for analyzing the causes and effects with respect to flood management. Furthermore the model will form a basis for setting up a surface water quality model, which will assist local governments and the South Florida Water Management district (SFWMD) assessing the water quality impacts of various management scenarios.

Present paper analyzes hydrologic response of alternate land development scenarios modeled using HSPF model. The study is conducted in southwest Virginia as part of a multi-disciplinary project sponsored by the USEPA. A scenario generator is devised using macros in MSWord and Excel that made possible to create HSPF input files to analyze about 50 different land development scenarios. The impervious fraction was found to be the most important factor in influencing hydrologic response of the test watershed. Also, HSPF model simulation results were found sensitive to choice of simulation time step.

An automatic calibration procedure for the MIKE 11/NAM rainfall-runoff model is described. The procedure considers multiple calibration objectives, including (1) a good simulation of the water balance, (2) a good overall agreement of the shape of the hydrograph, (3) a good agreement of peak flows, and (4) a good agreement for low flows. The shuffled complex evolution algorithm is applied for optimising the different calibration objectives simultaneously. The solution to the multi-objective calibration problem is given as a set of Pareto optimal solutions. From this set one can draw a single solution according to priorities of the different calibration objectives for the specific model application being considered. The calibration algorithm can explicitly take data and model errors into account by defining appropriate weights that indicate the importance to be given to particular portions of the hydrograph in the calibration process. Furthermore, a methodology for assessing parameter uncertainty is outlined. The procedure is based on a comparison of the distributions of the model parameters corresponding to the best and worst model simulations, respectively, obtained from a Monte Carlo sampling. An application example is presented that illustrates the use of the developed procedures.

There are two different problem aspects in multi-reservoir operation problem, that is, planning and real-time operation. For the planning problem, we may assume that we have the perfect knowledge of inflow unlike in real-time operating environment. For the real time operation, however, we have to use forecasted inflows at individual reservoirs instead of the actual inflow when we make release decisions. In this study, we evaluate the appropriateness of using a deterministic optimization model, which is called CoMOM(Coordinated Multiple Reservoir Operating Model) for real-time multi-reservoir operation. It is assumed that we do not have the perfect knowledge of future inflow and we simulate the situation of using CoMOM in real-time operational environment in Han River Basin in Korea.

A soil moisture accounting (SMA) algorithm was developed by the Hydrologic Engineering Center for the Hydrologic Modeling System (HEC-HMS). HEC-HMS succeeds the widely used HEC-1 hydrologic model as part of the next generation (NEXGEN) of hydraulic and hydrologic modeling software under development at the U.S. Army Corps of Engineers Hydrologic Engineer Center (HEC). As originally released in 1998, HEC-HMS was an event based simulation model with the exception of a simple deficit/constant loss function. SMA was implemented as a loss rate method in the HMS version released in the year 2000 (Version 2.0) and allows for long-term continuous simulation of hydrologic processes that occur and change over time in a watershed. This is achieved by simulating the movement of precipitation through storage volumes that represent canopy interception, surface depressions, the soil profile and two groundwater layers. Computational components of this algorithm also include evapotranspiration (ET), surface runoff, and groundwater flow. This paper details the computational steps and equations used in the SMA loss method to simulate these processes. Results of model application to simulate runoff for two watersheds are described. The watersheds are near Tifton, Georgia, and Riesel, Texas, and periods of simulation were eleven and seven years, respectively.

Laboratory experiments were carried out to determine minimum self-cleansing velocities for preventing deposition of sediment in upward sloping and vertical pipes of inverted siphons. Tests were made using sediment sizes of 0.78mm and 4.3mm in a pipe of 150mm diameter for eight angles of inclination between 0deg; and 90°. The criterion for self-cleansing was defined as the minimum velocity needed to prevent the formation of separated dunes in the pipes. For a given sediment concentration the self-cleansing velocity was found to be a maximum at pipe slopes between about 30° and 37.5°. Analysis of the data enabled the results to be described by a single formula valid for any slope of pipe between horizontal and vertical.

The city of Alor Setar in Kedah, is an important developing centre of business and communications for the Northwest of Malaysia. However, the capacities of the existing storm drains in Alor Setar are severely restricted as a result of sediment deposits washed-in during high intensity rainfall events. These deposits result in stagnant, polluted areas of water within the catchment and a loss of hydraulic capacity needed to deal with large storms. Methods of sediment deposition prediction have been applied to UK catchments with limited degrees of success. The application of these methods has been used to propose an improved sediment management strategy for Alor Setar. The methods involve the development of a simplified hydraulic model of the test catchment and the prediction of areas within the system where deposits are most likely to occur. Using this formation options for invert trap placement can be developed in order to determine their most effective locations. Further analyses are also proposed in order to determine the fill rates of these traps throughout an average year. A proactive maintenance plan can therefore be developed in preference to the reactive maintenance methods currently employed This planned programme of maintenance should ensure that best use of traps is made at all times in order to protect the system from flooding and pollution problems.

This paper summarizes the design of passive automatic flushing systems and grit control structures within the north east portion of the City of Cambridge tributary to the Alewife Brook. This work is under construction as part of a $60 M sewer separation program sponsored by the Massachusetts Water Resources Authority (MWRA) and the City of Cambridge. Grit deposition and debris accumulations are severe in the existing system of combined sewers, storm drains, and sanitary trunk sewers due to the flatness of the area. This condition is exacerbated by the outlet hydraulic constraints imposed by the Alewife Brook (shallow stream) and downstream constraining sanitary siphons (again because of the Alewife Brook). Complete separation of the area is envisioned, ultimately to be served by separate sanitary sewers and storm drains. The use of pumping systems to lift flows from sewers and drains to permit self-scouring velocities is prohibitively expensive. To overcome this problem automated flushing systems using quick opening (hydraulic operated) gates discharging collected stormwater are being constructed together with downstream collector grit pits at four locations covering a distance of 1220 meters for storm pipes ranging in diameter from 1.4 meters to 1.2 meter x 2.7 meter box culvert (storm trunk drain). New 450 millimeter and 600 millimeter sanitary trunk sewers 1000 meter in length will be flushed daily using spent filtrate water from the City of Cambridge's new water treatment plant (CWTP) currently being constructed in the same area. Construction of all work is underway and will be completed by the end of 2000.

A new model for modeling suspended sediment from an on-stream stormwater management pond is presented. It is based on Krishnappans' model of flocculated settling in still water, which was extended to dynamic conditions and verified by experiments with stormwater pond sediment in a laboratory rotating flume. The model was derived from first principles, but some input parameters, such as floc properties, had to be obtained by calibration, and input parameters describing flow field properties were obtained from a k - ε turbulence model. Simulated suspended concentrations vs. time, produced with the calibrated model, agreed well with flume measurements.

In this paper the formation of transporting sediment is given theoretically and experimentally with high-performance computers. In uniform materials and on a uniform slope, a series of uniform bends will develop. This development is described theoretically and a mathematical model is compared with the experimental data. Bed load particles move through an alluvial flume under the action of gravity, fluid drag, lift, and friction associated with the loss momentum to the bed via collision.

The bed material transport capacity in sand-bed streams is often estimated by computing the bed load, and then estimating the suspended bed material load using the diffusion equation with the reference bed layer concentration as a boundary condition established from the bed-load estimate. The total bed material load is then the sum of the bed- and suspended bed material loads. Common formulations for the suspended bed material load assume that the presence of suspended sediment does not affect the fluid characteristics or the suspended sediment concentration profile. Einstein and Chien using experimental data, showed that this assumption is not reasonable for sediment concentrations exceeding about 100,000 ppm by weight, which are common in steep, sand-bed arroyos. Woo developed a numerical solution to the diffusion equation that accounts for the effects of suspended sediment concentration on the fall velocity, fluid viscosity, and eddy diffusivity. This solution accurately predicts the suspended sediment concentration profile under high concentration conditions and converges to the clear-water solution at low concentrations.

Numerical calculations are performed for the nonsorbing contaminants within a sediment beds with bedforms. The effects of channel slope, hydraulic head, and dispersion on contaminant concentrations, mass flow rate, and location of the concentration front are determined. It is found that the flow induced by the bedform is largely responsible for the mass transfer of contaminants into the water column. The results also show that mechanical dispersion in the sediment bed may significantly increase the contaminant mass flow rate from the source.

In order to study the effect of different parameters on the amount of afflux due to rectangular pier, extensive experiments were conducted. The variables under study were upstream Froude number, contraction ratio and angle of pier axes with respect to flow direction. A regression-based model was developed which enables accurate determination of afflux.

One of the world's most densely populated nations, Bangladesh is also one of the poorest. More than 125 million people live within this South Asian country's total area of 144,000 km² (about the size of Wisconsin), which amounts to an average of 868 persons per square kilometer (or almost 2,250 persons per square mile.) Rivers are the most important geographical features of Bangladesh. Alluvial river plains, which dominate 90% of the country,are very flat, never rising more than 10 m above sea level. The two great rivers of the Indian subcontinent, the Ganges and Brahmaputra, divide Bangladesh into six major regions, which correspond to the six governmental divisions. The Ganges, which drains the southern slopes of the Himalayas, enters Bangladesh from the northwest and is joined by the Brahmaputra in the center of the country to form the world's third largest river, after the Amazon and Congo. The Ganges and Brahmaputra Rivers both receive new names once they pass into Bangladesh: the Ganges becomes the Padma, while the Brahmaputra is known as the Jamuna. South of the capital city Dhaka the lower Padma joins the Meghna River, which flows from the northeast. Lower reaches of the Meghna expand in width to around eight km during the wet season, and much more during large floods. The combined river delta is the largest in the world, beginning more than 320 km from the Bay of Bengal.

The dominant discharge is essentially the discharge that transports the most sediment over time. In the process of calculating the dominant discharge for Napa Creek in California, an apparent calculation deficiency was found in SAM, a hydraulic design package for flood control channels developed by the US Army Corps of Engineers. The collection and processing of hydrologic and sediment data for Napa Creek required the production of a flow duration curve and sediment gradation curves, respectively. Computer software HEC-RAS was used for hydraulic analysis; SAM was used for hydraulic, sediment, and dominant discharge calculations. Several different sediment transport equations were used for sediment discharge analyses, namely, Yang, Einstein (total-load), Parker, Einstein (bed-load), Proffitt (Sutherland), Engulend-Hansen, and Schoklitsch transport functions. Furthermore, Quattro Pro was employed when the SAM computer model did not effectively calculate the sediment discharge duration curve due to an apparent model deficiency. An explanation of the apparent deficiency is given along with a recommendation for improving the SAM model. A weighting system was developed to reduce but not eliminate subjectivity for assessing the applicability of the sediment transport functions used during the analysis based on data ranges reported in the SAM User's Manual.

Experiments were conducted to study the distribution of sediments at a channel bifurcation. The test rig consisted of a straight main channel, which bifurcated into two branch channels of different widths. The test rig was a mobile bed with fixed bank. Four different types of noses were used to study the phenomenon. For each nose, three upstream discharges viz.: 20 1/s, 30 1/s and 40 1/s were used. The evolution of bed level and the variation of discharges in the downstream branches were discussed. The ratio of the downstream discharges per unit width (q₁/q₂) and the ratio of the sediment transports per unit width (s₁/S₂) were estimated and set to the general nodal point relations which described the distribution of sediments to the downstream branches.

An understanding of the transport mechanism of gravel-bed rivers is very important for the river management and engineering works, e.g. prediction of sediment yield of a watershed. The main objective of this study was to conduct a series of laboratory experiment to investigate the effect of the particle gradation on the incipient motion of gravels, the particle segregation, and the transport rate of nonuniform gravel. A specially designed sediment feeding system was used in this experiment. The steep flume was a "semi-recirculating" system, i.e., only the water flow was recirculated. The median sizes of 15 mm and 7.5 mm, and gradation coefficients of 1.5 and 2.0 were selected for the particle size distributions of nonuniform gravel. Transport of nonuniform sediment is much more complicated than transport of uniform sediment due to the interaction among the particles with different sizes. It was found in this study that the gradation of nonuniform gravel had a significant effect on the particle mobility, the particle segregation and the sediment transport rate. An attempt was made to develop a transport relationship for nonuniform gravel using dimensionless parameters with a representative particle size. In addition to the 36 sets of data collected in this study, 635 sets of existing data for gravel with both nonuniform and nearly uniform sizes were analyzed. The side-wall correction method was employed in the calculation of the mean boundary shear stress. In addition, a modified Schoklitsch-type sediment transport equation was developed. Reasonable predictions were obtained using the two empirical relationships developed in this study for the conditions tested.

Lake restoration is a complex activity. Many modifications may have unintended results if not all variables are taken into account. Lack of careful evaluation of these variables may not result in the esthetic or fisheries benefits that were intended. Most lake rehabilitation projects are required because of excessive sedimentation and / or nutrient loading. Sedimentation and nutrient loading either cause esthetic problems or reduced fishing opportunities. The best way to improve a lake is to improve the watershed or water supply by implementing best management practices (BMP's). When the lake environment has already been degraded, implementing BMP's do not produce the desired results, sedimentation and nutrient loading still exceeds acceptable levels, and water clarity and chemistry are limiting factors, then rehabilitation of the lake itself is required. The use of sediment traps, sediment bypassing, and hypolimnetic siphoning or discharge need to be explored in these cases. This paper presents an overview of all of the above factors in lake rehabilitation with an emphasis on sediment traps, sediment bypassing, and hypolimnetic discharge and how each method affects water quality. Applications and limits of applicability for these methods will be discussed.

A number of major water resource ecosystem restoration projects are currently underway in the United States. One is focused on the Everglades, a unique ecosystem in southern Florida. The Everglades restoration project is estimated to cost some $8 billion over a period of about 50 years. It is not only a challenge to scientists attempting to understand the physical and biological processes affecting the unique hydrology and ecology but also to planners and decision makers dealing with the social dynamics of the people living in the area. People impact the Everglades, and the rate of population growth in southern Florida shows no sign of decreasing. The outcome of this ecosystem restoration effort will largely be determined by the land use decisions and social activities of these people over the next several decades. It may also be influenced by political decisions made far outside the region, such as in Washington with respect to sugar subsidies (i.e., our relations with Cuba). It may be influenced by climate change (e.g., sea level rise) as well. In this complex physical and social environment, scientists from private and public agencies are working together with all concerned stakeholders to plan and manage the restoration project. Models are being developed and used to estimate the various impacts that may result from any plan or management policy. As expected, there exist conflicts among various stakeholders. If there was ever a challenge for those involved in building models and associated decision support systems for impact prediction and for communicating information to multiple stakeholders having quite different interests and concerns — all in an effort to obtain some consensus or shared visions of what should be done, and why — this project provides one.

Shared vision modeling is a disciplined approach to developing water resources models for conflict resolution. Shared vision modeling requires both the use of time-tested planning procedures and the active participation of those likely impacted by a water resources plan. Stated most simply, shared vision models are computer models developed by stakeholders, water managers, and water planners that incorporate planning objectives and performance measures into a framework that allows the generation and evaluation of alternatives in a manner that facilitates conflict resolution. These models typically contain social, economic, and environmental impacts as well as hydrologic and hydraulic analysis. Because they require the active participation of a wide range of individuals, they must be easy to construct and modify, not just easy to run. In 1998, the Water Resources Planning and Management Division of ASCE developed a Task Committee on the Use of Shared Vision Modeling in Water Resource Planning. This brief paper presents the committee's goals and purposes. At the ASCE 2000 Joint Conference of Water Resources Engineering and Water Resources Planning and Management in Minneapolis, a summary of the committee work will be presented.

The Otay Water District, located in San Diego, California, identified the need to replace 3,000 feet of deteriorating pipeline. As the Inter-Connection Project was developed, the pipeline grew from 3,000 feet to over 12 miles. The modified project allows the transfer of water between two distinct service areas. This pipeline, both eliminated and delayed construction of additional reservoirs in both service areas. Through the utilization of a pipeline, the District optimized their storage capacity of potable water, and increased service reliability to their customers. The project has provided several opportunities for partnerships through the creativity of the District. The District developed a construction philosophy of "Construction Manager/Constructor" (CM/C) for the project. The CM/C philosophy employed the construction manager as the general contractor, in a not-at-risk relationship, who in turn was responsible for securing, through public bidding, subcontractors to complete specific aspects of the work. The project was divided into 54 distinct construction contracts, creating increased opportunities for small and local contractors to participate in what has become the single largest capital improvement project undertaken by the District.

Planning is an act of abstraction in which alternative decisions are tested by comparing the future results we think those decisions will cause. The future of planning is shared vision planning, but the future of planning is not assured. The coincidence of planning and public involvement with the revolutionary performance improvements and price reductions in personal computing made shared vision planning possible. There is little doubt that computer advances will allow far more powerful and comprehensive shared vision planning tools, but will they influence decisions? If planning does not produce obviously better solutions than one can achieve in the courts, the legislature, by regulation or by simply doing nothing, then they will not. The challenge to water resources planners is to confront the reasons why planning has not lived up to its promise and fix it if it can be fixed.

Constructed wetlands used for stormwater management must be able to adapt to continually varying pollutant loads and volumes of stormwater runoff. Where treatment wetlands are also being used for mitigation, development and maintenance of a proper wetland habitat are key elements to receiving credit. Success of a wetland to effectively treat runoff and maintain the proper habitat can be attributed in part to the types of vegetation and relative location within the wetland with respect to inflows and water depth. Literature suggests that the failure of many constructed wetlands in either of these goals can be attributed to poor planning of planting species and position. The following paper presents the results of several experiments which tested establishment, survival, and biomass accumulation of three types of common wetland vegetation in "bucket" and bench scale wetlands. Typha spp., Scirpus spp., and Phragmites spp. were assessed under various combinations of establishment time, duration of exposure to pollutant loads, and concentration of pollutant load. Results are used to develop effective strategies for planting constructed wetlands to enhance development and survival of constructed wetland systems used for stormwater management and mitigation credit.

A significant source of nutrient input to water bodies is from grass clippings and leaves (yard debris) washed into drainage systems during storms. Brevard County Surface Water Improvement conducted a study to determine the nutrient release rates from grass clippings and leaves in order to better understand the chemistry and resultant pollutant loading mechanisms. Sixty-gram samples of mixed freshly cut St. Augustine yard grass (Stenolaphrum secundalum) and oak leaves (Quercus sp.) were placed into opaque containers. Coarsely filtered storm/ditch water was added to fill the containers to the 8-liter marks. Samples were allowed to go anaerobic, typical of wet sump best management practice (BMP) structure conditions, and tested periodically after soaking and processing. At intervals of: 0, 1, 5, 9, 14, 22, 34, 50, 70, 130, and 180 days, triplicate bucket sets were agitated to simulate mixing from stormwater influx, then poured through a Number 35, US Standard Soil Sieve, and the liquid analyzed. The solids that remained in or on the sieve were analyzed, and the results compared to those of the corresponding liquid phase. The results presented depict "typical" east-central Florida lawn and leaf litter decomposition and nutrient release rates. This information may be useful in the selection or site design of BMP's for treating nutrients in stormwater, and determining cleaning frequency.

In July 1997, Brevard County's Stormwater Utility Program installed a new type of trash and sedimentation control device called a continuous deflection separation (CDS) unit. This was the first American installation to use CDS Technology which was developed in Australia. After installation, autosamplers sere placed upstream and downstream of the CDS Unit and a year's duration of sampling data have been collected Monitoring has shown that the CDS unit has provided an average 52% removal efficiency for total suspended solids and 31% removal efficiency for phosphorus.

This project, which is funded by the National Cooperative Highway Research Program, includes both a synthesis of current information and a plan to guide future research. The issues to be studied include regulations and permitting, runoff water quality characteristics, best management practices, receiving water impacts, and habitat impacts. The tasks include a detailed review of existing information plus digitization of key information and software development to identify gaps in the current state of knowledge. A nationwide survey of experts will assist in identifying existing information. After the information has been scanned to identify gaps, the team will identify and prioritize future research to fill the gaps. This research plan will then influence future NCHRP funding on highway runoff research projects.

Lag time is an essential input to most flood hydrograph models. Lag times for sixteen urban and developing watersheds in the Kansas City area were determined from gaging data. Relevant physical characteristics of the streams and watersheds were computed from digital spatial data with GIS. Multiple-regression analyses were performed to identify significant explanatory variables and to develop regression equations for lag time. Two regression equations are recommended. Lag time appears to decrease exponentially with increasing road density and impervious area.

The City of Portage is pioneering a comprehensive approach to storm water management in light of the Phase II Storm Water regulations. The approach will serve to define the application of the now elusive "Maximum Extent Practicable" (MEP). This is accomplished through the design and construction of a regional storm water treatment system for a 1.9 km² urban drainage area. The treatment system will be highlighted with recreational trail ways, new wildlife habitat, and tax-base enhancement through reclamation and redevelopment of ineffective smaller detention basins. The design incorporates, in one plan, four of the six minimum control measures identified in Phase II regulations for the largest storm water outfall to a surface water in Portage, MI.

Anticipating Phase II Storm Water regulations and a TMDL, the City of Portage is taking proactive steps to address requirements for water quality improvement. In a unique project, a storm water treatment system is currently under design which will significantly increase the quality of life for city residents while meeting and exceeding regulatory requirements. This new regional storm water treatment facility will be integrally linked to a recreational trail way system, provide treatment for runoff from 1.9 km² (463 acres) within the highly developed urban core targeting 80% pollutant removal rates, and double the length of existing trail ways in the city. The regional facility will allow reclamation of land for re-development by replacing several private, on-site detention basins that are poorly maintained and ineffective at pollutant removal and flow moderation. The new facility will be municipally-owned and maintained. Its design combines several storm water treatment options, including a sediment pond, wet detention basin and wetland treatment. More than a mile of scenic trail ways connecting major retail and recreational facilities will be integrated into the site plan. These trail ways allow access to the 10.4 ha (25.8 acres) comprising the storm water treatment area that provides wildlife habitat, a restored stream corridor, recreational access, flood protection and opportunities for environmental education. A monitoring program has been established to evaluate the effectiveness of the treatment processes. This paper presents the unique integration of community benefits with the innovative storm water treatment system.

Many existing storm water dry detention basins designed solely for storm water runoff peak discharge magnitude abatement as well as detention basins designed both for water quality and quantity control fail to achieve necessary levels of non-point source pollutant loading reduction. This correctable situation has necessitated the demonstration of various retrofitting techniques on existing systems. An easy and relatively inexpensive retrofitting technique is modification of the basin outlet. The area chosen for such a project was a single-family home development community located in Morris Township, New Jersey. The first modification to the existing dry detention basin consisted of the reduction of the pipe outlet diameter, by placing an outlet box in front of the existing outlet pipe. The second modification was attaching a floating riser, a buoyant outlet device, to the outlet box. The floating riser removes only the surface layer of an impounded storm. Either basin modification resulted in a longer detention time than the original basin did for the same volume of runoff inflow. However, no conclusive correlation between the pollutant removal efficiency and the detention time was determined. Rather, it was found that the pollutant removal efficiency in the field was strongly dependent on the inflow concentration. Therefore, the pollutant removal efficiency must be evaluated in the context of variable inflow concentration. The outflow concentration may be a more reliable and useful criterion for evaluating the water quality performance of a detention basin. The outflow concentrations of total phosphorus were found to be significantly reduced due to basin outlet modifications.

This paper presents a computational methodology and software model for direct evaluation of optimal highway drainage inlet design. The optimal design is defined as the most economical combination of stormwater inlet type, size, and location subject to a maximum width of gutter spread. The problem is formulated as a discrete-time optimal control problem in which a genetic algorithm is interfaced with a hydraulic simulation model. The simulation model follows guidelines established by the Federal Highway Administration and is used to implicitly solve governing hydraulic constraints that yield gutter discharge, inlet interception capacity and spread according to a design storm. The genetic algorithm is used to select the best combination of design parameters and thus solves the overall optimization problem. The new methodology allows for a reduced total cost of highway drainage since its primary aim is to minimize user-defined costs that can be associated with materials, initial construction and long-term maintenance. Capabilities of the model are demonstrated through application to a hypothetical highway drainage system. The example reveals that genetic algorithms and the discrete-time optimal control methodology comprise a comprehensive decision-making mechanism that can be used for cost-effective design of storm water inlets.

Criteria for selecting riprap to protect bridge abutments against scour were investigated. experiments were conducted with a spill-through abutment under clear water conditions for various riprap sizes, apron sizes and apron extents. The abutments were constructed from the bed sediment and riprap was laid on top, to a thickness of two stone diameters. Tests were run for a period of 24 hours, after which the abutment was assessed for failure, either total, partial or not at all. An abutment was adjudged to have failed if the side slopes of the abutment (including the riprap blanket) had shifted in any way. Initially, the riprap apron was constructed following the HEC-23 recommendations. This recommendation was found to be conservative in all cases, and was reduced by increments in subsequent tests until an abutment failure occurred. This process was carried out for two abutment lengths and three riprap sizes. A useful relationship was found between the dimensionless riprap size and apron extent, showing a clear zone of partial failure.

Reinforced earthen slopes through mechanically stabilized earth (MSE) utilizing Geogrid are an effective and innovative channel stabilization measure which can eliminate requirements for highly visible structural control measures, particularly when difficult environmental or physical site constraints are involved. Current advances in new construction material have resulted in soil retention systems through reinforced earth construction which offer a new applications for flood control and streambank protection control measures. Most conventional applications of reinforced earth systems have primarily involved earthwork slope stabilization or roadway projects. However, reinforced earth systems offer numerous advantages to conventional streambank stabilization techniques which include: structural reinforcement of the earthen streambank, ease of construction with normal fill operations, low costs, and an inert mattress that becomes an integral matrix with the earthen bank. Geogrids are typically manufactured of high density polyethylene (HDPE) resins that resist elongation when subjected to high load for long periods of time. The geogrids can carry large tensile load applied in one or two directions, and their open structure interlocks with the natural earthen fill material. The geogrid installation results in a structurally stable embankment which reacts similar to a gravity wall. In addition, the geogrid constructed streambanks can provide a steeper than normal slope face which can be naturally landscaped and provides an aesthetic alternative to conventional streambank revetments. Geogrid slope stabilization technology offers a new form of "bioengineering" with unique long term engineering properties and avoid common failure mechanisms. In addition, there are a variety of proprietary industry systems that combine the use of geogrid that have potential flood control and erosion protection applications. Comprehensive design procedures are reviewed for applied designs utilizing geogrid material for reinforced earth stabilization of channel banks, including the hydraulic and structural evaluation steps involved in the design of this type of system. Several unique flood control projects utilizing geogrid technology are evaluated, focusing on the different applications and constraints for each project.

Riprap design procedures often stipulate the use of angular shaped stone materials. However, angular shaped riprap materials are not always available nor economically feasible at all construction locales. Alluvial materials are often available at remote locations that yield relatively high quality materials, but the rock is usually rounded in shape. Currently, the stability of rounded riprap compared to angular riprap is unknown. A physical testing program was performed subjecting rounded rock to overtopping flow. Soil embankments 76 cm in height with slopes of 20%, 25%, and 30% were constructed in a recirculating flume. A geotextile was placed atop of the embankment, followed by a shallow (6 cm) filter/bedding material layer. Rounded riprap with median stone sizes of 2.4 to 9.9 cm (0.94 to 3.9 inches) was placed in layer thicknesses of 1.5 to 3 times the median stone size on the bedding. Flow was conveyed over 12 test configurations and slowly increased until the rock layer integrity was disrupted. The data analysis yielded a procedure through which the stable median rock size may be determined as a function of the degree of roundness, rock uniformity, slope, and unit discharge.

Riprap is one of the most commonly used methods for channel stabilization (both bank and bottom). Presently, there are many riprap design methods used in the United States. Some of the prominent methods are the U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, U.S. Geological Survey, California Bank and Shore Protection, Federal Highway Administration, Isbash, and ASCE. This paper briefly discusses each of these methods, the theory and data used in their development, recommendations on their usage made by their developers, and the observations and recommendations of the authors of this paper. To illustrate these points, hypothetical examples are presented and a computer program is used to easily make comparisons between these seven methods. These examples are utilized to properly interpret the applicable range for each method and assist in the decision of which method to use. This was done by examining the results of combinations of shear force and velocity versus the representative (D₅₀) riprap size for each method.

The U.S. Army Corps of Engineers' Hydrologic Engineering Center (HEC) recently introduced a new software program, Flood Impact Analysis (HEC-FIA) Version 1.0. HEC-FIA provides state-of-the-art techniques to calculate post-flood or forecasted-flood damage for urban and agricultural property. It is also used to determine the flood damage reduction benefits attributed to flood control projects (reservoirs and levees). This paper presents the capabilities of HEC-FIA and shares how it can be applied as a planning and engineering tool. The HEC-FIA models developed for the various District offices will be used to help illustrate the program. The paper will relate how GIS techniques were used to help build the damage functions and how the damage/impacts were divided between urban and agricultural categories, numbers of structures and population. This paper will discuss how project benefits are calculated and distributed. Finally, the paper will report on the program output and how it provides information to the planner and engineer.

Impacts of ecosystem restoration alternatives and the associated affects of flood damage for the Tres Rios study area, located near Phoenix, AZ, were studied using the Hydrologic Engineering Center River Analysis System (HEC-RAS) in concert with HEC-GeoRAS. HEC-GeoRAS is a set of procedures, tools, and utilities for processing geographic information systems (GIS) data in ArcView GIS, using a graphical user interface. The interface allows preparation of geometric data for import into HEC-RAS and generation of GIS data from exported HEC-RAS simulation results. Automated GIS processing procedures in HEC-GeoRAS provides a valuable and expeditious method for repetitive hydraulic model development during floodplain analysis. Further, the GIS is ideally suited for visualizing proposed alternatives and the associated flood impacts.

Since 1992 Devils Lake, a terminal lake in North Dakota, has risen nearly 7.6 meters (25 feet), flooding an additional 362 square kilometers (sq. km.) (140 square miles (sq. mi.)). In July 1999, the lake reached a peak elevation of 441.11 meters (1447.2 feet) above mean sea level, with a corresponding surface area of 518 sq. km. (200 sq. mi.). Like the Great Salt Lake in Utah, Devils Lake is highly saline due to the long-term accumulation of salts from evaporation. To alleviate flood impacts on surrounding communities, the St. Paul District, U.S. Army Corps of Engineers is investigating the feasibility and environmental impacts of pumping saline water from the lake into the fresher Sheyenne River water. The Sheyenne River flows through Lake Ashtabula, a Corps of Engineers reservoir, and into the Red River of the North, which then flows north to Lake Winnipeg in Canada, thereby creating interstate and international concerns. The Hydrologic Engineering Center's HEC-5Q program is used to address downstream water quality impacts. By simulating with- and without-pumping scenarios on the Sheyenne and Red Rivers, a quantitative evaluation of the effects can be made, including alternative operating plans for the outlet and operation of Lake Ashtabula. Vast amounts of data are conveniently handled by the HEC's Data Storage System (HECDSS). HECDSS is used to preprocess the data for input to HEC-5Q and to post-process the data from HEC-5Q for analysis.

The Hydrologic Engineering Center (HEC) has added Lateral Weir and Split Flow Optimization capabilities to our river hydraulics software, HEC-RAS. The new capabilities are part of the steady flow computations and work in subcritical, supercritical and mixed flow regimes. The lateral weir optimization allows for general weir profiles that span multiple cross sections and computes the flow based on a sloping water surface from cross section to cross section. Lateral weirs can include multiple gates with gate openings specified by profile. The split flow algorithm enables the steady flow program to balance flows between streams to solve a looped or diverging network. This paper presents the capabilities that have been added to HEC-RAS for Lateral Weir and Split Flow Optimization. The input specifications and computation procedures are described.

In urbanized watersheds, storm water discharges from industrial facilities potentially major but poorly understood source of pollutants. Estimates of pollutant load from industrial facilities may vary with many factors, but must be refined if watershed based regulations, such as the Total Maximum Daily Load (TMDL) program, are to be implemented fairly and effectively. Storm water runoff from industrial facilities under the NPDES program are regulated through a general permit, which among requires facility operators to implement a limited monitoring program. This research used monitoring data reported by industrial facilities to estimate the contribution of pollutant load into the upper San Gabriel watershed in the Los Angeles region. First, we attempted to control for data variability caused by factors such as facility size, impervious portion of surface area, rainfall intensity, and seasonal antecedent rainfall, but no relationships were identified. Next, we estimated total loads from industrial facilities in the watershed. Industrial facilities constituted less than one percent of the watershed area, but contributed between 10% and 70% of total copper load and between 15% and 60% of total zinc load. Load estimates were strongly affected by variability in concentration data and estimates of the number of non-compliant facilities, but less strongly by spatial variability in rainfall.

Villanova has recently been awarded an EPA 319 Non-point Source Implementation Grant from the Pennsylvania Department of Environmental Protection to retrofit an existing detention pond creating a stormwater wetland. An overview of the project focus and framework is presented. The objectives of the project are (1) to provide non-point pollutant treatment to a degraded urban watershed and stream segment through conversion of a stormwater detention basin to an extended detention wetland best management practice (BMP); and (2) to create a permanent wetland BMP demonstration site that has substantial research, education, and technology transfer value for the future.

Recognizing that urban storm water is a significant source of water quality impairment, federal and state water pollution control regulations have been implemented requiring industrial facilities to take steps to monitor and minimize the exposure of storm water runoff to pollutant from their operations. In the seven years since the regulations were implemented, approximately 9080 California facilities have taken at least the initial step to comply by self-identifying and seeking coverage under the general permit program. To achieve full compliance with the regulations a facility must first evaluate operations and exposures followed by the development and implementation of a site-specific pollution prevention and management plan plan. This research describes the California population that has sought general permit coverage and characterizes activities and physical factors that may predict a site's propensity to contribute pollutants to storm water. Eight SIC codes were found to represent 54 percent of all permittees. Direct observations established that while the majority of sites were highly impervious and conduct more that one regulated activity, the intensity of such exposed activity and housekeeping varied substantially. Twenty-eight percent of complying facilities were found to occupy sites of one acre or less. These findings raise questions about whether the general permit applied equally to all is the appropriate allocation of resources to reduce pollutant load.

Hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), demonstrate a high affinity for fine particles, the so-called suspended solids or sediments (SS) in natural waters. This study focused on PAHs from the SS collected from non-point source runoff into Santa Monica Bay, California. The runoff came from the urbanized Los Angeles watershed of Ballona Creek, which is approximately 325 square kilometers in size and developed primarily with residential and light commercial industries. In the 1997–98 rain season, an El Nino year, storm events were monitored to show the pattern of non-point source runoff. The primary objective of this study was to determine the types and concentrations of organic pollutants associated with the suspended solid phase. A calculation of the mass of the pollutants for each storm was conducted. Other objectives included 1) to study for the relationship between storm flow and pollutant loading, including the determination of a first flush, 2) to compare concentration of pollutants with an environmental indicator and 3) to do a simple comparison between point source and non-point source sources of pollution.

The Eugene Water and Electric Board (EWEB) retails water to customers located within the City of Eugene, Oregon. Current annual average demand for the full system is approximately 55 megaliters per day (mgL/d) (25 mgd) with a peak day demand ranging up to 155 mgL/d (70 mgd). Water is obtained from the McKenzie River and treated at the Hayden Bridge filtration plant. Capacity of the treatment system is 158 mgL/d (72 mgd). Treated water from the plant is pumped to Eugene along a dedicated corridor (approx 5.6 km) through the City of Springfield. At the eastern limits of Eugene, the water transmission lines split into three primary supply lines to serve Eugene (Intertie). A base level reservoir is located at the end of each supply line. Above the base level system are five elevated service levels layered along the south hills. Separate pumping and storage facilities provide water to each level. Reservoirs provide storage for ensuring consistent water pressure and flow throughout the system and emergency storage for short periods of duration.

One of the primary uses of water distribution system models is to identify problems and evaluate alternative solutions to existing or anticipated problems in water distribution planning. While numerous papers have been written on use of optimization for design, optimization techniques rarely fit real problems. Rather than discuss the generalities of modeling, this paper uses the Comprehensive Planning Study (CPS) (i.e. "master plan") of the water distribution system for the Pennsylvania American Water Company's (PAWC) Wilkes-Barre/Scranton system to illustrate the kinds of issues that drive modeling efforts in a master planning study.

As part of their recently completed water master plan, the City of Phoenix, AZ required a demand generator that would produce a demand set for hydraulic modeling based on user input for time-of-day, day-of-the-year, and year during the study period. The demand allocation had to be able to predict instantaneous demands at any point in the system, formulate base demands, and create an aggregate peaking curve for use with hydraulic models. Such a model was developed using the City's comprehensive GIS, the Visual Basic programming language, and a Microsoft Access relational database seeded with attributes required by common pipe network analysis software. The resultant model provides extreme flexibility. Demand nodes can be seeded using several methodologies, ranging from a simplistic inverse pipe-diameter model to comprehensive polygon overlay processing with nodal weighting, where weights can either be automatically generated or user defined. Subsequent to the Phoenix study, the demand allocator has been successfully applied to other smaller systems.

The Eugene Water and Electric Board (EWEB) retails water to customers located within the City of Eugene, Oregon. Current annual average demand for the full system is approximately 55 megaliters per day (mgL/d) (25 mgd) with a peak day demand ranging up to 155 mgL/d (70 mgd). Water is obtained from the McKenzie River and treated at the Hayden Bridge filtration plant. Capacity of the treatment system is 158 mgL/d (72 mgd). Treated water from the plant is pumped to Eugene along a dedicated corridor (approx. 5.6 km) through the City of Springfield. At the eastern limits of Eugene, the water transmission lines split into three primary supply lines to serve Eugene (Intertie). A base level reservoir is located at the end of each supply line. Above the base level system are five elevated service levels layered along the south hills. Separate pumping and storage facilities provide water to each level. Reservoirs provide storage for ensuring consistent water pressure and flow throughout the system and emergency storage for short periods of duration.

Feedback control of water quality in drinking water distribution systems using chlorine boosting is a complex, large-scale, multivariable problem. This paper presents some preliminary results on developing a partially decentralized adaptive control approach for water distribution networks. The approach is based on approximating the input/output dynamic behavior of chlorine concentration in the distribution system as a time-varying, discrete-time linear model with unknown coefficients. Each local adaptive control algorithm requires knowledge of the remaining control actions but feedback information from only one sensor output. A simulation study is presented to illustrate the approach.

An integrated approach to control of quantity and quality in water supply and distribution systems is proposed. The integrated control consists in optimising the operational cost, meeting a demand on water of desired quality and maintaining the constraints. This constrained optimising control problem is complex due to nonlinearities, large dimension, output constraints, mixed-integer structure of the variables involved, at least two time scales in the system dynamics and an uncertainty. A sub-optimal two-level hierarchical control structure is proposed that allows incorporating the desired controller functions and yet making the synthesis of these functions possible. The algorithms for implementing the functionalities are proposed and discussed.

Reliability analysis water distribution systems is a complex task. It requires both the quantification of reliability measures and criteria that are meaningful and appropriate, while still being computationally feasible. This paper focuses on a tailor-made reliability methodology for the assessment of regional water distribution systems in general, and its application to the regional water supply systems of Nazareth in particular. The methodology is comprised of two interconnected stages: (1) analysis of the storage — conveyance properties of the system, and (2) implementation of stochastic simulation through use of the US Airforce Rapid Availability Prototyping for Testing Operational Readiness (RAPTOR) software.

Reliability analyses are performed on two large-scale water distribution systems in the Tucson Metropolitan Area in Arizona. Reliability is defined as the probability of satisfying nodal demands and pressure heads for various possible pipe failures (breaks) in the water distribution system. An existing reliability model based on a minimum cut-set method is linked to a steady-state simulation model that implicitly solves the continuity and energy equations. The results from the simulation model are used in the reliability model to define minimum cut sets and determine the values of system and nodal reliability. A discrete failure relationship is used with absolute failure if pressure heads fall below a prescribed minimum. Comparisons of results illustrate the similarities and differences in the design of each system under varying operating conditions. Design alternatives to improve reliability are discussed.

Skeletonization is the process of representing a water distribution system by selected pipes. Historically, skeletonization was the norm and was dictated by limitations of the computer models or the resources available to develop the network representation. With the advent of more powerful models and data handling techniques, skeletonization is no longer essential but becomes a trade-off between the potentially greater accuracy that can be achieved with more detailed networks and the costs associated with data gathering, network building, output analysis and longer computer run times associated with the more detailed representations. In this paper, accuracy, use, cost, parameterization, and calibration issues associated with skeletonization are discussed. A case study is presented in which four different levels of skeletonization are modeled.

A simple integrated approach to calibration of water network model and leakage distribution is proposed. The distribution of water losses is studied as the first step in the calibration procedure of the mathematical model. In order to calculate the leakage from pipe an empirical formula which takes into account the length of the pipe and mean pressure, and also contains certain coefficients, is used. For determination of leakage the pressure measured in control nodes is used. For defining pressure in other nodes an iteration process is applied which determines the leakage and pressure intermittently. Following that process the roughness values of the pipes are varied to minimize the differences between the calculated and measured pressures. Pipes with almost similar roughness are grouped together and corrections of roughness for each group are set up. This is followed by adjusting roughnesses with linear optimization process, where the increments of roughnesses are determined on condition that the sum of the squares of the differences between the simulated and measured pressure in control nodes will be minimal. A trial-and-error approach has been used for the comparison as well. The method was used by elaborating a software package for water distribution network of the City of Tallinn.

Creating diurnal demand curves should be a fairly straightforward process using tank water level and flow meter data to reconstruct demands. However, there are frequently problems with the raw data and how those raw data are used. This paper discusses some of those problems and how they can be avoided.

Smart management of distribution networks calls for a deep understanding of domestic water- use patterns. It is important to analyse not only average values, but how and why these vary from house to house. Diurnal patterns affect daily network scheduling and leakage analysis whilst the makeup of demand - for example the ramp-up in hot weather - affects longer-term water -resource planning. The paper discusses analysis of usage patterns from nearly 2000 accurately-logged domestic sites, with meters logged every 15 minutes. Various ways of characterising usage are outlined, including occupancy models and spectrums of usage frequency. Alternative models are proposed for domestic usage, with explanatory variables covering both the physical aspects of the site and the life-styles of its occupants.

The optimal design of water distribution systems for expansion, rehabilitation, reinforcement or rezoning is a complex process requiring systematic examination and evaluation of the design alternatives. The issues that make these design problems difficult to solve are presented in this paper, and the case for formal optimization methods is made. The reasons for adopting the genetic algorithm (GA) as the search technique are explained, and an outline of the GA methodology is given. Design variables include pipe locations and diameters, valve status, pumps and reservoirs. The inclusion of pumps into the optimization process requires that both the design and the operation of the network should be considered. Provision of new or expansion of existing service reservoirs is also described. Including service reservoir storage in the optimization requires simulation of the filling and emptying of the reservoirs through the daily cycle of demands, in addition to analysis of the instantaneous peak and emergency flows. A new methodology is used to increase the efficiency of the GA and to include the reservoir balancing in the problem formulation. Finally, the problem of rezoning an existing system for leakage control is presented using a case study. Substantial savings on manually produced solutions are demonstrated. These savings justify the use of genetic algorithms for these types of problem, and indicate that most other manually designed schemes may be costing far more than is necessary.

A new method is proposed for the least cost design of looped piped networks under various levels of redundancy using a genetic algorithm. Various levels of redundancy can be obtained by considering the number of pipes to be taken out of service at any one time. As a result, a tradeoff curve of redundancy and cost can be developed. The approach is being extended to consider different measures of redundancy as well as other performance criteria. Such extensions are more computationally demanding and are therefore being implemented using a distributed GA.

Computer models are vital for the evaluation and management of hydraulic infrastructure systems. This paper describes the development of an efficient computer optimization software system, called H₂ONET Designer, for use in obtaining the least-cost design and rehabilitation of municipal water distribution piping systems. The software system links an object-oriented hydraulic network solver and an optimization model in a fully integrated graphical mapping and database management environment to provide an effective computer aided decision-support tool for water engineers. The optimization model is based on a variation of the genetic algorithm employing a global search strategy and delivering reliable solutions in sub-quadratic times. Least cost design and improvement solutions are chosen to satisfy designated performance constraints on the network hydraulics for any given range of demand loading and operating conditions. Network improvements can include cleaning, cleaning and lining, pipe expansion, and/or installing new pipes (as constant diameter pipes or split pipes of differing diameter) that can either parallel or replace existing pipes. The constraint set prescribes minimum bounds on node pressures and maximum bounds on pipe velocities and hydraulic gradients that are allowed in the system. Comparisons with published results show improved performance, rapid convergence, and applicability to large-scale water distribution systems. Enhancement of water distribution infrastructure planning and management is a principal benefit of the proposed software system.

A least-cost methodology is presented for use in upgrading existing single-source water distribution networks in order to sustain any single component failure (link or node). The methodology is developed by casting the network reliability problem in terms of an explicit level of system redundancy. As a result, minimum cut set computations are avoided as well as the need to select an arbitrary level of system reliability. The design engineer can thus select a design based on the total cost and the desired level of service. The proposed methodology provides two different levels of system redundancy: topologic and hydraulic. Topologic redundancy is satisfied through the application of methods from graph theory. Hydraulic redundancy is satisfied through the application of genetic optimization and hydraulic network simulation. The developed methodology is tested against a known optimal solution for a single source system.

The England and Wales Water industry has changed dramatically in the past ten years since privatisation in 1989. The once fully government operated water authorities are now operated by private companies that are publicly listed. The operation of these companies is regulated by the government appointed Office of Water Services (Ofwat), who have ultimate responsibility in setting the limits for the prices charged the consumers for their water supply. Ofwat has implemented a rigorous auditing regime that involves extensive reporting of the valuation, performance, extent and conditions of the water distribution system assets. Serviceability is increasingly being used to describe the performance of the assets and it is used as a guide on the level of expenditure required to maintain the system. The measures used in Ofwat's auditing regime are those that are being suggested to assess an asset's serviceability. The concern from the water companies was that these regulatory-based performance measures are backward looking, and cannot be directly translated into a pro-active planning strategy. The optimisation technique genetic algorithm is used to address the suitability of these measures in a decision making framework. The genetic algorithm has increasingly been used in the development of rehabilitation strategies, providing information on the trade-offs that need to be made throughout the process. The other major constraint on the work is the data available. Therefore the investigation will utilise the data recorded on the GIS packages used by a typical water company in England.

Analysis and control of pressure transients in pipelines continues to be a tedious process, despite availability of sophisticated modeling packages. The complexity is magnified when the transient suppression devices, such as surge tanks, need to be designed for minimum cost. The paper describes a surge tank design model that obtains an optimal set of decision variables while satisfying a specified set of pressure constraints. The model was developed based on a bi-level optimization framework and it employs a genetic algorithm in minimizing a nonlinear objective function. The model was applied to optimize sizes of two surge tanks on an example water distribution network. Enumeration of the entire solution space demonstrated that the solution obtained by the genetic optimization model is close to the global optimal solution, while requiring only a fraction of computational time that was necessary for enumeration.

This paper describes the use of Particle Swarm Optimization (PSO) for optimizing pump operations in water distribution systems. Here, the decisions are pump speeds for variable frequency drive (VFD) pumps. The objective is to minimize the energy costs while maintaining pressure heads and tank levels within acceptable bounds. The pressure bounds may be set such that leakage losses will be reduced. Alternatively, target pressure heads may be defined and the objective would become to minimize deviations from those targets. PSO is a stochastic optimization methodology along the lines of evolutionary techniques and based upon the concept of simulating social behavior. Unlike genetic algorithms, PSO considers continuous variables. Solutions computed by PSO are derived from both local and global searches. This allows PSO to consider solutions near the vicinity (local) of the starting point, in addition to a possible solution located within a global region. The search process for new point(s) includes consideration of the pervious best solutions. Thus, results have shown that this method converges to global optimal solutions.

The optimization of production and transport costs in a drinking water network has been modelized using various operational research methods in recent years. For several years we have been building models used on large water networks, managed in real time. For short calculation times, linear programming has been chosen. Our optimization model is based on an objective function that minimizes the daily proportional costs and on physical constraints such as tank size. In order to calculate the flows being able to forward on the network an hydraulic model is used. In certain networks, one constraint has not yet been incorporated into optimization models. It is associated with the operating conditions of the water treatment plant. To avoid problems with water quality, a waterworks must be able to operate continuously. The problem is difficult to solve because Bellman's principle of optimality cannot be applied. To take account of this extra operating constraint, we propose a method based on linear programming with mixed variables. We introduce set-up, stop and start-up variables. The optimization model is resolved using the Cplex Solver. The Solver uses several shortcuts that reduce the time taken by a conventional branch and bound algorithm. This method provides satisfaction by maintaining computing times compatible with real time network management. For example, we can solve the optimization of a real network with two different resources (river and groundwater), five tanks supplying 20,000 inhabitants in about 30 seconds.

Disinfecting the water supplied by a distribution network with chlorine or other disinfectants directly acts on its quality. Good water quality imposes lower and upper bounds on the chlorine concentrations all over the network, at any time. These concentrations may be controlled at the sources and at intermediate points of the network, the booster stations, but determination of the optimal chlorine injection strategy is usually not easy, as the transport and reaction phenomena modifying the chlorine concentrations are complex. We propose linear programming formulations to determine the locations where disinfectant must be added and optimize the injection patterns. The variables we choose are the discretized chlorine concentration values at the nodes of the network and the locations where booster stations are needed. The constraints are linear relations between these variables, obtained thanks to a special code simulating the evolution of the concentrations over the network; they describe the interdependence of the variables over the network and take explicitly the system's dynamics into account. Besides, lower and upper bounds on the optimum concentrations are also introduced. Finally, the criterion we propose here is the minimization of the maximum difference between optimum and target concentration values. Solving the proposed optimization problem not only gives the best booster stations locations and injection patterns, but also calculates the corresponding chlorine patterns at all the nodes of the network.

In the context of the preservation of the water quality in drinking water distribution systems, network managers have to maintain chlorine residual during the distribution step. Since the chlorine residual decreases with the residence time, the disinfection process applied at the outlet of the treatment plant is often not sufficient to reach a good spread-out of chlorine in the system. To achieve this specific goal, implementation of booster stations may be a strategic goal. Moreover, a good balance between main chlorination and booster chlorination may help to limit the concentration of disinfection-by-products (DBPs). In order to define optimal booster programs, especially in large utilities, the CIRSEE has developed a new strategy of selection of rechlorination sites.

Disinfectant residual maintenance has always been a concern to water utilities, and is a requirement of the total coliform rule. Booster disinfection is a strategy that is being applied to add disinfectants at strategic locations throughout a water distribution system. A designer needs information about the network hydraulics and water quality to decide how to locate and operate booster stations. This paper describes a formal optimization method that uses such information systematically to locate the minimum number of booster stations within a water distribution network. The method is demonstrated to be practicable for real distribution networks. The optimization model is in the form of a maximum set covering (MSC) model, and can be solved using a branch and bound procedure. Branch and bound methods are typically time-consuming but rigorous. An alternative heuristic solution method is available due to the particular form of the MSC model. Heuristic methods typically require less computational effort than optimal methods, and the present heuristic performs well for the cases examined. The attributes of the model solutions are illustrated through an application to a real network.

This paper presents a total social cost framework for optimisation of the design and operation of water distribution systems, including water quality considerations. The objective function includes the traditional capital and operating costs of the infrastructure. To this are added the social costs associated with waterborne diseases, the risk of cancer due to disinfection byproducts and a cost due to poor aesthetic quality of the water. In this paper water quality is considered purely in terms of levels of disinfectant (chloramine and chlorine) throughout the system. A case study for Yorke Peninsula in South Australia is analyzed. The results from the case study illustrate the need to consider seasonal variations and their impact on water quality levels in addition to the traditional peak hydraulic loading conditions. The genetic algorithm optimization models used to solve this problem are quite complex and require long run times. Ways of reducing this complexity need to be explored in future studies.

State estimation is the process of computing the optimal estimates of the time-varying states of a system from time-varying measurements. With the exception of fast dynamics such as water hammer, water distribution networks are said to be in equilibrium or steady-state notwithstanding the fact that the flows and pressures may be rapidly varying with time. The class of state-estimator applicable to water distribution network monitoring is called a static state-estimator. This paper reviews a sub-set of these methods including weighted least squares, iteratively re-weighted least squares and new method of including bounds on parametric uncertainty in state estimation.

A state estimator is an algorithm that computes the current state of a system from on-line measurements. It is a widely held belief that since state estimators are used in the power industry they are appropriate for water networks. However, one of the key differences is the observability of the respective systems. Power systems have sufficient measurements to give high redundancy values whereas water networks are not typically as well metered. Furthermore, there is a much greater level of uncertainty present in water network models (parametric uncertainty) and in the measurements. The measurement uncertainty is largely due to the predominance of pseudo-demand measurements necessary to make up for the lack of real transducers. Before state estimation can be used, it is essential to know how observable the water distribution network is. A poorly observable system will produce misleading state estimates. This paper will present a new method, using a linear fractional transformation (LFT), which separates the parametric uncertainty in the network parameters from the nominal system. This will be compared numerically with results from a Monte Carlo simulation, applied to a thirty-four-node test network. Finally, using an algorithm based on eigenfunction analysis, the paper will demonstrate how additional measurements can be chosen in order to make the system more strongly observable.

While state-estimation is widely used for electrical power systems, it is still in its infancy for water distribution systems. The main reason for this is that water systems, being underground, are much less accessible for metering. Traditionally, flow and pressure telemetry has been supplemented with pseudo-demand data in order to achieve sufficient data redundancy. Since the pseudo-demands are already estimates, there is a danger of circular conclusions. In this work, the least-squares state-estimation equations are re-formulated such that normalised demand factors within District Metered Areas (DMAs) are used instead of pseudo-measurements. This formulation has several advantages. Firstly, one source of error is eliminated since a nominal time profile for the pseudo-demands is no longer required. Secondly, the demand factors are in some sense orthogonal to the DMA boundary measurements such that swamping of the real flow measurements is avoided. The practical implementation of the above state-estimation method for large systems, however, is non-trivial. Considerable numerical analysis has been employed in order to solve large systems without shortcut approximations. Results will be presented for a 5000 node South London test area covering 88000 properties.

A novel input-output model of water quality in water distribution systems is presented as a partide backtracking algorithm. The algorithm is a simpler and more efficient version of that described by Zierolf et al. and is extended to consider the case of storage tanks (the tank algorithms will be described elsewhere, although simulation results are given here). The input-output model provides information that is not available using traditional simulation approaches: the various paths that water takes between input source and output node and time, decomposed into their associated time delays and impact coefficients. Such information constitutes a complete description of the input-output behavior under typical assumptions of first-order chemical decay or production reactions. Thus the output behavior can be calculated for any source quality input, and the revealed mathematical form of the input-output behavior may be useful information for certain applications such as feedback control. More generally, the input-output model may be useful in understanding the effects of water quality processes that are flow path-dependent, since those paths are made explicit.

The significance and impact of leaks in a pipeline system creates new opportunities of leak detection. In essence, the concept is to use the pressure response from a transient event to locate and size a leak. Previously, Brunone determined both the location and size of a leak on the basis of the pressure trace during a transient event at a measurement section on the basis of the well-known properties of pressure waves. More recently, formal inverse transient algorithms have been developed. The goal in this study is to see if the genetic inverse transient procedure can correctly locate and size a leak in a "blind test". More specifically, the pressure signal at the downstream end of the system as well as the basic pipe properties will be fed to the inverse procedure to see if the predicted existence, location and magnitude of the leak can be accurately determined. The paper reviews the results of the blind calibration procedure as well as summarizing the key background required to understand these developments. The significance of this study data to the later quality problem, and particularly to the danger of contamination of the pipe contents, are given special emphasis.

Water quality deteriorates between the points of treatment and consumption in water distribution systems. Many water quality problems have been reported in dead-end pipes and other remote service areas where intermittent flows are common. To improve predictions of water quality in peripheral zones of the distribution system, network models need to account for advective-dispersive transport under low flow conditions. Experimental results presented here show that hydrodynamic dispersion can be a significant transport mechanism in intermittent laminar flow, a condition that is prevalent in dead-end lines of a water distribution system.

A dynamic-stochastic model of a reservoir and municipal water system has been developed. The model is written in Stella II. The overall structure of the model is discussed; the physical- environmental- and end- use- segments are explained and sample simulation results are presented. The application of the model for policy analysis relating to the management of a municipal system are illustrated.

Failure in residential supply pipes (the final stage of waters distribution journey) is a comparatively rare event. However, there are many such pipes so the aggregate of these failures can have a significant impact on overall network demand. On a mature network there are various failure modes; some can persist without being obvious to the householder. This Paper outlines analysis of supply-pipe leakage patterns in over 2000 accurately-logged domestic sites. The meters are located at the boundary box and logged every 15 minutes. Many types of property are logged and some demographics are known; often several years data is available for analysis. The frequent logging allows persistent supply-pipe leakage and wastage to be differentiated from intermittent final demand. A model has been developed to allow the life-cycle of supply-pipe leakage to be studied using this data. The analysis also shows the distribution of loss-rates from such leaks and the effect of pressure variation to be examined. The Paper concludes with some observations on the economics of detecting and repairing supply pipe leakage on the basis of the panel data.

In this project, artificial neural networks (ANN) are used for the estimation of water quality parameters of River Gediz in the western part of Turkey. Gediz River basin contains the third largest city of Turkey. Moreover, it is the major agricultural area in the region as well as highly industrialised. There are so many pollution sources although clean water is highly demanded. Therefore, estimation of quality parameters from relatively easily measured river parameters is of great importance to maintain adequate water quality monitoring in the river. Selection of appropriate input parameters to estimate another one is key to use ANN. This is essential to obtain maximum success with minimum error. The input parameters selected must be those which affects most the output one. In this study, therefore, to estimate the amount of total dissolved solid (TDS), the river discharge, the water temperature and PH (acidity) are chosen as input parameters. A generic ANN software was run for different values of input parameters. This comprised training and test phases. For the most successful result of training for each month, the test phase was undertaken. The values passing the test phase successfully showed that ANN could successfully be used for estimation of water quality parameters that are relatively difficult to measure from those easily-measured. The outputs of such studies are essential for river water quality modelling studies.

With the increasing degree of automation in Dutch water management the need for control systems and design procedures for control systems is also evolving. Traditionally these control systems were used for water level and discharge control only. With the measurement equipment that is currently available, improved water quality control becomes possible too. A PhD research is currently investigating this subject. To carry out this research an adequate numerical model of the relevant processes such as water movement, transport of dissolved matter is required. This paper will discuss possibilities of water quality control and the use of a numerical model called MODIS that can be used for the simulation of controlled water systems.

A water quality study of the proposed Olivenhain Reservoir in San Diego County, California, was conducted to guide the design of the inlet and outlet towers and mixing facilities from a water quality operations perspective. Seasonal salinity management and taste and odor control by selective withdrawal and mixing were evaluated. The Olivenhain Reservoir is a joint project of the Olivenhain Municipal Water District (OMWD) and San Diego County Water Authority (CWA). OMWD will use the reservoir to supply water to their proposed membrane filter water treatment plant. CWA will use the reservoir as part of their Emergency Storage Project (ESP) for seasonal storage. Olivenhain Reservoir will have a storage capacity of about 24,000 acre-feet (AF). Olivenhain Reservoir will be connected to the CWA aqueduct with a pipeline. The design of the planned connection between Olivenhain Reservoir and Lake Hodges, an existing reservoir with a capacity of about 30,000 AF was also evaluated. The predicted water quality profiles for three operations scenarios were evaluated and compared with measured water quality profiles from nearby reservoir. Recommendations were developed for selective outlet design and reservoir mixing management strategies. The water quality model will be used to guide operations and maintenance decisions for salinity management, nutrient control, mixing, and outlet elevation selection.

A framework is presented to analyse alternatives of water planning measures. This framework is then applied for assessing different measures for Nile water pollution control. Assessment is undertaken by weighing the cost of at-source wastewater treatment against the degree to which the Nile water quality is improved. A Decision Support System for water Quality Management is used as a computational tool. Results are obtained for both optimistic and pessimistic scenarios of population growth and industrial expansion. The results indicated that treatment at-source may not be cost-effective if made for only few point sources along the Nile.

Monitoring of the Big and Little Blue Rivers in Nebraska for atrazine three times during the 1980s and early 1990s revealed 369 out of 385 samples contained atrazine in detectable concentrations. The concentrations of atrazine within the samples varied from 0.05 to 166 micrograms per liter. AGNPS is a computer model that analyzes nonpoint-source pollution and prioritizes potential water quality problems in rural areas. The event-based model uses geographic cells to represent upland and channel conditions. Within the framework of the cells, runoff characteristics and transport processes of sediment, nutrients, chemical oxygen demand and pesticides are simulated for each cell and routed to the outlet. This permits the flow at any point in the watershed to be examined. Upland sources contributing to a potential problem can be identified and prioritized where remedial measures could be initiated to improve water quality most efficiently. The objective of this study was to (1) calibrate AGNPS to four runoff events between May 14 and June 1, 1996, from a Big Blue River watershed in Rural York County, Nebraska and (2) simulate atrazine runoff for each storm event comparing computed results to observed atrazine concentrations. Hydrologic calibration was accomplished by varying watershed curve numbers to fit peak flow rates and runoff volumes. The measured watershed atrazine application rate was 1.57 kg/ha on May 1, 1996 with an assumed 75 percent application efficiency. The watershed average computed atrazine concentrations for each storm event was an order of magnitude higher than the observed average concentrations. The event simulated means ranged from 220 to 280 micrograms per liter, while the observed means ranged from 8.6 to 33 micrograms per liter. Less atrazine may be simulated to be adsorbed to sediment and more dissolved in runofF than actual conditions. Parameters that could be better computed to solve this problem may be the soil-water-partitioning coefficient and sediment enrichment ratio.

Almost 25 years after the passing of the Clean Water Act (CWA), the Environmental Protection Agency (EPA) has introduced the concept of Total Maximum Daily Load (TMDL). This concept encompasses the determination of the Load Capacity (LC) of a stream and the associated Waste Load Allocation (WLA) for point and Load Allocation (LA) for non-point source pollutants. A fundamental pillar of TMDL is the recognition that the conflicting interests and demands of potential users of an aquatic system need to be balanced. It is therefore imperative to include a framework that allows optimization as the omission of the latter causes excess costs that otherwise could potentially be reduced. This paper presents a methodology to develop a very efficient WLA procedure. Specifically, it incorporates the imposed environmental constraints and at the same time optimizes the discharge rates into the aquatic system. It is shown (using the Potomac River Estuary as an example domain) that using a 2-dimensional dynamic modeling approach with a high temporal discretization allows identifying optimum loadings for a large number of discharges along a stream. Various aspects like concentration of dischargers in a small stretch of stream, number and placement of monitoring nodes and varying water quality standards along the stream are investigated.

This paper presents an overview of the Environmental Protection Agency's (EPA) Environmental Technology Verification (ETV) Program which was established to overcome the numerous impediments to commercialization experienced by developers of innovative environmental technologies. Among the most frequently mentioned is the lack of credible performance data. It is believed that objective, independently acquired, high quality performance data and operational information on new technologies will significantly facilitate the use, permitting, financing, export, purchase, and general marketplace acceptance of such technologies. The ETV program was established to provide such data and information to the customer groups in order to accelerate the real world implementation of improved technology. This paper describes the ETV approach and two recently initiated pilot programs for verification testing of source water protection technologies and wet-weather flow technologies conducted in association with the NSF International, EPA's verification partner organization for these activities.

Due to an increased interest and concern about the Los Angeles urban environment, studies have begun to focus on the local water cycle and the impact of impervious land on the Los Angeles River. Findings from initial studies indicate that during the 1990s approximately half of the rain that fell in the watershed turned into runoff (which flowed to the ocean). Prior to 1930, less than 10 percent of the rain turned into runoff leaving 95 percent of the runoff to infiltrate into the subsurface. As the region continues to develop, (approximately 60 percent is currently urbanized the opportunities for rainfall to naturally infiltrate into the groundwater aquifers are reduced. With an ever-increasing population and even greater water demands, method are being explored to capture and direct storm water runoff for recharge purposes instead of ocean water discharge. This paper describes two efforts by partnerships made up of various publicly funded agencies and community organizations to test new stormwater retention technologies in the watershed to better manage stormwater and address the impacts of urbanization and imperviousness. These two efforts are the Broadous and Open Charter elementary schools.

Turbulent benthic boundary layers generated by breaking of internal waves along the sloping bottom of a stratified lake play a significant role in vertical mixing. Benthic boundary mixing in density stratified lakes was investigated by conducting laboratory measurements. The turbulence characteristics of a benthic boundary layer were investigated by using MSCTI (Micro Scale Conductivity and Temperature Instrument) in conjunction with LDV (laser-Doppler-velocimetry). The measurements indicate that the dominant flux path, the path along which particles travel, is along the benthic boundary layer and then horizontally into the main water body via intrusions. The experimental measurements conducted in the Hydromechanics Laboratory at Purdue University suggest that the: (a) breaking of internal wave on sloping boundaries generates a turbulent benthic boundary layer; (b) the thickness of the boundary layer can be scaled as H ~ (λωξL/(N cosθ))^(1/3), where λ, ω, ξ, are internal wave length, frequency, and amplitude respectively, L is the length of the sloping boundary, N is the buoyancy frequency, and θ is the slope of the boundary; and (c) the turbulence intensity in the benthic boundary layer exhibits an oscillatory behavior.

A study has been conducted to arrive at the most cost-effective and environmentally acceptable solution to the discharge of partially treated wastewater into coastal lagoons, lakes and offshore waters, where funding for complete conventional treatment plans has wither been severed or inadequate. Field data of water-quality parameters for effluents discharged out of wastewater oxidation ponds and constructed wetlands have been reviewed and analyzed. The case studies reported herein are those of natural treatment plants in the USA (California) and in the Middle East (Jordan). The results of the extensive work conducted at the natural treatment plant in Jordan and on the effluents discharged into the Zerka river indicate the viability of using treated wastewater for irrigation in the Jordan valley. The findings of the study suggest an appropriate and alternative solution to Alexandria's current disposal of primary-treated wastewater into Lake Maryout. The recommended scheme comprises an integrated system of oxidation ponds and a constructed wetland in the Maryout Valley prior to disposal in the lake or reuse for irrigation.

Several studies have suggested that small-scale fluid motion, scales smaller than a centimeter, influence the kinetics of biological and chemical particles in aquatic environments. One of the key intrinsic fluid flow parameters is the turbulent kinetic energy dissipation rate. The turbulent kinetic energy dissipation rate is obtainable through the indirect method of Batchelor curve fitting. The estimation procedure assumes homogeneous and isotropic turbulence at small scales. Therefore, the procedure requires partitioning each profile of non-stationary temperature gradient microstructure into stationary segments. In this study, ten profiles of temperature gradient microstructure measured in three inland lakes are analyzed by using a segmentation algorithm. Spectral changes in the temperature microstructure are compared using methods based on AR models and one based on wavelet analysis.

Field measurements of dissolved oxygen concentration, performed in a small harbour in Attica during spring and summer 1998, are presented. Synoptic surveys during morning and afternoon hours included D.O. concentration and temperature measurements in twenty one sampling stations inside and outside of the harbour basin. Measurements of wind direction and velocity, as well as wave measurements, were also taken. A seasonal trend of increasing water temperatures and decreasing absolute D.O. concentrations was observed. However, percentage saturation was increasing during the same period and sometimes even supersaturation was observed. D.O. concentrations in the harbour basin were found to be lower than those measured outside the harbour, in the vicinity of the breakwaters, in the order of 1–2 mg/l. D.O. concentration was higher in the area of wave breaking and more so with increased wave heights, especially for wind directions causing breaking waves on the breakwater. The field measurements are in general qualitative agreement with the laboratory measurements.

India has 16% of the world's population, roughly 4% of the world's water resources and 2.45% of the world's land area. With the scenario of population becoming around 1500 million by year 2050, and current status of land degradation and erratic monsoon; watershed development and management in a sustainable manner has become crucial. The activities in this area by government and non-government organisations have achieved varying degrees of success. Some foreign collaboration projects have also been implemented. Keeping in view the need for networking of efforts, a systematic co-ordinated research programme to cover the six ecosystems in twenty ecoregions by sixty research experimental watersheds has been proposed. This also envisages establishment of national data base for use in development of hydrological models including use of GIS, and appropriate decision support systems for stake holders. The co-ordinated programme of research watersheds funded by Department of Science and Technology is based on this concept proposal. It is expected to provide useful research outputs for improvement of watershed management activities in different regions of the country.

Bangladesh is inhabited by about 125 million people in an area of 148,000 square kilometer and is located within the floodplains of three great rivers of the world: the Ganges, the Brahmaputra and the Meghna. The current population density of about 850 per square kilometer is the highest of any nation in the world and its economy is heavily dependent on agricultural productions. During the decade between 1984–85 and 1994–95, share of agriculture to GDP declined from 41.8 to 32.8 per cent. Projection of employment to the year 2020 shows that till that time agriculture will continue as the major source of employment by absorbing over 40% of the labor force. The total annual flow of the river system in Bangladesh is about 1.5 billion cubic meters of which 1.36 billion cubic meters (93%) originates from upper regions in India, Nepal and Bhutan. During the monsoon season (June to October), there is plenty of water (85% of the total flows) and opposite happens in the dry season (November to May) when the flow of the rivers go down so much that in certain areas of the country normal economic life is seriously disrupted. The south western region of Bangladesh which is solely dependent on the Ganges waters for its sustenance has been facing major environmental hazards since the operation of the Farakka barrage in 1975 in the upstream of the river in India. The above water syndrome, too much during the wet months and too little during the dry months, points to the necessity of better management of available water resource. The ongoing National Water Management Plan (NWPM) will make an assessment of the overall availability of water both spatially and temporarily and will project the balanced use of these resources.

The Devils Lake basin in North Dakota is experiencing an wet climatic cycle and rapidly rising lake levels. The basin is a closed basin within the Sheyenne River drainage area, a tributary to the Hudson Bay in Canada. The rising lake levels have caused flooding problems in several towns and in tribal Indian and rural areas. Some remedies costing up to $300 m have been attempted by raising highways, sewer systems and other infrastructure. However flooding continues with significant damages occurring. The solution to the problem is the construction of a pumped outlet to the Sheyenne River. This paper will discuss some of the details required to build partnerships between federal, state and local government agencies and officials. The authorities provided by various public laws and the Boundary Waters Treaty of 1909 provide a background for the network of institutional agreements and working arrangements needed to build the outlet. Multi-disciplinary teams including engineers, environmentalists, fish and wildlife biologists, economists, nonprofit interest groups and others have been required throughout the projects' planning and design phases. Specific issues relating to the interaction between Congress and the Executive Branch agencies will be discussed. The paper concludes with an update on the status of the project including a briefing on what has worked and what hasn't worked. An update on estimated costs will also be provided.

The El Niño-Southern Oscillation is used here as a basis tor long-range exceedance probability forecasts that have the potential for improving the management of water resource systems in eastern Australia and the western United States. An exceedance probability forecast is important for the design and operation of water resource systems, that require a high degree of system reliability. Past studies have shown that the hydrology in these regions is strongly effected by ENSO. The relationship is strong enough to develop a seasonal streamflow forecast in both of these regions. In eastern and south-eastern Australia, there is a strong tendency for below normal hydrologic conditions following an El Niño event. In the western U.S., the potential of making a six-month lead time forecast of spring-summer runoffis demonstrated for the Columbia River basin. The skill associated with these forecasts is better than the baseline "climatology" condition and the potential benefits of using these forecasts in the management of water resource systems is explored. For instance, the potential benefits of using these forecast are demonstrated for an urban water supply system and for a rural irrigation system in eastern Australia.

Presented herein are hydraulic-design guidelines for deploying debris-skimming booms at riverside diversions, such as water intakes for thermal power stations, municipal water-supply facilities, and irrigation canals. Based on laboratory-flume tests and boom literature, the guidelines aim to reduce debris passage into, and accumulations at, diversions. The guidelines include boom distance out from the diversion entrance, boom orientation to the diversion, and boom draft. Optimal deployment of skimming booms is related to the flow field at riverside diversions. The flume tests established how these variables influence the physical processes governing skimming-boom performance, and led to recommendations on effective deployment of straight and bent booms for debris flushing. Bent booms comprise two segments (one angled from upstream and one parallel to the diversion), and are the more effective form of boom for wider ranges of river and diversion flows.

Water quality response to reservoir water withdrawal from Pea Hill Arm of Lake Gaston, a non-tidal reservoir tributary with pool elevation changes driven by main lake hydroelectric power plant and other source-sink operations, was examined in this study. The point of water withdrawal in the Pea Hill Arm tributary is located upstream, from the main lake at a location that causes water withdrawal and pool elevation changes in the main lake to influence both the magnitude and direction of tributary flow causing longitudinal velocity null conditions to occur under some conditions. The study focuses on control of withdrawal rate and timing to optimize both quality of water remaining in the tributary and quantity of water that can be safely withdrawn. Research was first conducted assuming steady state conditions and later under spatiotemporal variability experienced in the reservoir with main lake pool elevation fluctuations at the tributary boundary. A source-sink water quality modeling framework using USEPA SWMM and QUAL2E models was developed first to model in-lake water quality in Pea Hill Arm of Lake Gaston under steady state conditions. The initial framework assumed unrestricted downstream flow with negligible affects from a submerged culvert at the interface with the main lake. The affect of hydraulic head across the submerged culvert was also assumed to be negligible.

The purpose of this project is to develop computer modeling tools to assist in evaluating the impacts of future land use changes as well as point source discharges and spills on the Occoquan Reservoir. The project is being funded by Counties, Cities, and Towns throughout Northern Virginia (it is truly a regional effort) and is being overseen by the Northern Virginia Planning District Commission. The Occoquan Reservoir water supply serves approximately 1 million people in the Virginia suburbs of Washington, DC. Over the years, urbanization in the 560 square mile watershed and changes to point source discharges have raised concerns with the long-term health of this critical water supply. In order to evaluate potential threats to the water supply, this project involves developing a detailed watershed model using EPA's HSPF and linking the HSPF model to the Army Corps of Engineers' CE-QUAL-W2 (vertically-stratified hydrodynamics and water quality simulation). These linked models will allow future development scenarios to be evaluated in terms of potential threat to water supply.

Public concern about the environment, a commitment to environmental stewardship, environmental laws and regulations, and a desire to increase operational efficiency are prompting state and local governments to mitigate, reduce and eliminate the environmental impacts of highway maintenance. At the same time, these agencies must remain focused on their fundamental mission of providing a safe driving condition, offering the level of service customer's desire, and preserving the highway infrastructure. Public accountability also requires cost-effective use of public funds. One major area of maintenance involves work in and around streams and rivers. Drainage structures and channels must be kept open and clear of debris to minimize the possibility of wash outs and undermining of adjacent embankments. Additionally, emergency repairs to structures and roadway fills caused by flooding have to be accomplished to protect the integrity of the structure and the roadway. All these activities have the potential to damage streams and subsequently degrade the water quality through the action of erosion and sedimentation.

Diffusion process is the process by which matter dissolved in water is transported from one part of a system to another. The radial diffusion rate, salt concentration distribution with time and distances were studied experimentally for 36 undisturbed cylinders of clay soils in Southampton University, UK. In this paper, using the previous data, three empirical formulas were developed for salt concentration distribution as a function of the radius of the samples R and distance r from the center of the core for time periods H (H = 24, 48, 72 hours) A mathematical formula was developed to determine salt concentration ratio distribution at any time t and distance r from the center of the soil's core, with initial concentration C₁ and surface concentration C₀ (assumed zero) for a range of the diffusion coefficients D from 4.8 x 10^–6 cm² sec⁻¹ to 1.6 x 10⁻⁵ cm² sec^–1. The equation could predict the time needed to reduce salt concentration in soil by leaching process to the permissible value. This may give the opportunity to save 1/3 of the quantity of water allocated for leaching process in the Nile Delta area depending on the degree of salt accumulated in the soil. This study highlights the importance of the radial diffusion process in the rationalization of water, which is very important in the policy of water management. Especially in parts of the Nile Delta, where the reused of drainage water for irrigation is a common practice.

With an annual population growth rate of over 8%, Yemen's capital Sana'a, is facing an increasing pressure in all municipal service sectors. This pressure is greatest in municipal water supply since the city depends exclusively on a non-renewable groundwater aquifer that is being mostly utilized (mined) also for irrigation. The growing water deficit in the Sana'a basin area is currently being satisfied from the fossil groundwater storage. The study examined, for water supply alternatives, the current cost to consumers and their capacity and willingness to pay for domestic water (‘value to the users'). More specifically, this paper describes and analyzes the structure and cost of the domestic water supply market in Sana'a: (1) the coverage by the public and private water supply systems, their water quality, and the ensuing choices for consumers, (2) the cost and value of different types of domestic water supply, (3) the implications of present and future domestic water demand, and (4) alternatives for future water supply including social economic constraints to water transfer and reallocation.

This paper develops a methodology for charging for water use through simulating investment scenarios to improve the quantity and quality of water resources. The case study involves the Paraopeba river basin in the Brazilian state of Minas Gerais, which includes 48 cities and covers an area of 13,300 km². The basin is home to some 900,000 individuals and besides the drinking supply, the most important water uses are agriculture and mining The study first considers physical, hydrological, social, and economic aspects by inventorying the current and potential uses and users of water resources. Then, a water budget is developed regarding supply and demand for use and/or sewage dilution for current and year-2006 scenarios. Facilities and equipment are proposed to improve water quality and to optimize water resource allocation in the basin, the costs of which are also evaluated. The model considers water quality goals according to users' capacity to pay. The use of economic instruments is based on the recognition that water is an economic good and hence must be linked to its actual monetary value.

Effective management of the highly variable water resources of a river basin requires an understanding of the reliability with which various quantities of water can be supplied, under various conditions, within institutional constraints. Implementation of a water rights permit system in Texas has motivated efforts to expand capabilities for assessing water availability at any location on any stream considering the impacts of water management throughout the river basin. A surface water allocation system was implemented during the 1970's-1980's pursuant to the Water Rights Adjudication Act of 1967. The Brown-Lewis Water Management Plan enacted by the Texas Legislature in 1997 authorized development of a statewide water availability modeling system. This legislation specifies that models for six river basins are to be completed by December 1999 and models for 16 other basins must be completed by December 2001. The modeling effort is built upon the water rights permit system but is designed to support planning as well as regulatory functions.

This paper describes the use of long-term streamflow forecasts for improved reservoir operations. The forecasts make use of climate conditions (El Niño Southern Oscillation and Pacific Decadal Oscillation) to derive operating policies that increase flows for fish while maintaining water supply reliability. The impacts on historical instream flows and reservoir storage volumes of six climate conditions as a function of PDO and ENSO are investigated. Four simulation experiments are performed using current instream flow requirements and three alternatives, including increasing instream flows by 10% and 25%, and a variable trigger based upon climate conditions and reservoir storage volume. Performance is based upon impacts to reliability and ability to meet increased instream flow targets. This study demonstrates that PDO-ENSO conditions can be used to develop reservoir operating policies that provide more flows for fish with little impact on system reliability.

The United Nations classifies Korea as a water scarce nation. Rain is concentrated in three summer months, so that dam construction is a must, but there is no more "appropriate site" for a large-scale dam. South Korea has Indiana-size landmass with 45 million people. Naturally, South Korea is not blessed by even distribution of rain. Man-made thousands of reservoirs, including 10 multi-purpose dams are supplying the necessary amount of water. However, what is the necessary amount of water? Environmentalists argue that the government policy-makers are planning to construct more dams. Estimating the necessary water quantity is based on two different criteria. The government policy makers are forecasting the future water consumption based on the past trend analysis, whereas the environmentalists are forecasting the future water consumption based on the different scenario, for example, reduced consumption due to the higher water price mechanism, and more tree-planting in the mountain and valley.

The paper analyses the pros and cons of water demand management (WDM) measures where water scarcity affects more than one sector of the economy e.g. agriculture and industry. A cost-benefit analysis method is proposed to work out the appropriate level of conservation in each sector. Reference to the case of Egypt is often made. A discussion is made on internalising the environmental, social, and political criteria in the cost-benefit analysis.

The CALFED Bay-Delta Program is an open, collaborative, state-federal-stakeholder effort seeking to develop a comprehensive long-term plan to restore ecosystem health and improve water management for beneficial uses of California's Bay-Delta system. Water transfers can play an important role in achieving that goal. As such, CALFED has identified several actions to be implemented that will help improve the framework upon which the water market operates throughout California. This paper will describe those actions and how implementation is being achieved or is planned to occur over the next several years. This will include discussions regarding stakeholders involvement and how the CALFED agencies, responsible for oversight for most of the water transfer proposals, are coordinating to resolve differences of opinion and to streamline repetitive processes.

Water marketing in Southern California has been increasingly sought to augment water supply for both urban and agricultural users, although it has yet to become a wide spread mechanism of water allocation. This paper explores the potential and limitations for Southern California water markets using an economic-engineering network flow optimization model, CALVIN. CALVIN is used to identify the most limiting constraints to a free water market in Southern California, to estimate how a market would affect overall Southern California water use, to preliminarily assess the economic benefit of more flexible policies, and to explore the characteristics of a free market. Results from CALVIN suggest substantial economic benefits exist for implementing water market mechanisms and these economic benefits could be achieved with relatively small quantities of reallocation of agricultural water. An ideal water market in Southern California also would reduce pressure to increase imports from the State Water Project and the Colorado River as higher valued urban water shortages are decreased.

An overview is presented of renewable fresh water resources, urban water supplies and waste management systems in four Asian countries. The water resource, water supply and waste management development plans for certain urban areas in each country are looked at. Conclusions are drawn on the approaches which would improve water resource protection and help ensure sustainable urban water supply and waste management systems in the countries studied.

A GIS application called GISHYDRO is being used by the Maryland State Highway Administration (MdSHA). The GIS application is being used to save time in developing the hydrologic parameters for a drainage area with a size of approximately 150 square kilometers. To be more specific, GISHYDRO was used to develop RCN numbers for existing and ultimate land use conditions as well as provide initial estimates for times of concentration and to develop a TR-20 model. The use of GISHYDRO saved the project a significant amount of time by automating the process of developing RCN numbers, drainage areas, slopes, stream lengths and times of concentration. Also the results show that it provided this automation with a great deal of accuracy. The watershed is a rural watershed consisting primarily of forested and agricultural lands. The watershed's slopes are between 0.005 and 0.010 m/m, there are no major reservoirs, and the valleys are narrow and provide little storage for attenuation. The watershed is dendric and has a relatively high drainage density. The subwatersheds range from 8.26 square kilometers to 29.16 square kilometers, with the average subwatershed around 15.54 square kilometers.

Maryland, as well as many other East Coast states, is home to the federally threatened Bog Turtle (Clemmys muhlenbergii). Bog turtle populations have been declining since the late 1970s due to draining and filling of wetlands due to industrial, residential, and commercial development; pollution; poor land use practices; and the illegal pet trade. Although there has been much recent research on the habitat, genetics, and movements of bog turtles, there has been little investigation into the hydrologic inputs to bog turtle habitats. A proposal to construct a new highway bypass and industrial park in central Maryland have provided an opportunity to do this. The project is unique because there has been extensive interagency coordination in an effort to improve roadway infrastructure and economic development while also protecting a federally threatened species. An extensive biological assessment is being undertaken in order to investigate the sustainability of the bog turtle wetlands from both water supply and biological perspectives.

Constructed wetlands are an important component of plans to treat stormwater runoff from agricultural areas in South Florida. Several large wetlands are being constructed as part of a plan set forth by the Everglades Forever Act (EFA). Interim goals for these facilities include reduction of long-term total phosphorus concentrations to 50 ppb and restoration of the area's natural hydropatterns. To meet these goals, six Stormwater Treatment Areas (STAs) are being constructed on 18,210 ha of agricultural lands. STA 3/4, a 6,742 ha facility, is the largest of the stormwater treatment areas and the last to be constructed under the EFA mandates. STA 3/4 is being designed to serve the Miami Canal and the North New River Canal basins. It has a maximum design flow rate of 165 m³/s and a footprint that extends approximately 11 km from east to west and 6 km from north to south. To support the design of STA 3/4 models are being developed to simulate the hydraulic profiles and internal flow patterns within each treatment cell (STA 3/4 has five internal cells). Because of the large land area covered by the STA, use of a 2-dimensional (2-D) hydraulic model is necessary to simulate the performance of inflow and outflow control structures, spreader canals, collector canals, and variations in topography within the STA. The Federal Highway Administration's FESWMS-2DH software was selected for use in the design of STA 3/4. Models have been developed using topographic information collected from conventional and GPS surveys, a vegetation survey, and field data collected at other constructed wetlands. To date the models have been useful in demonstrating flow patterns resulting from the location of the control structures and how variations in structure spacing can impact flow patterns, thus reducing short-circuiting within the marsh areas.

Storm water management and watershed management philosophy has been rapidly evolving over the past few decades. Among other things, the objective of these projects is control of quantity or rate of runoff and/or quality control. In short, designers seek an engineering solution which is environmentally sympathetic. To achieve this objective the water resources engineer must apply a holistic or ecosystem approach to the project. When applied to a water-related project the terms "holistic" and "ecosystem" imply an approach that will protect the environment, or specifically, the receiving streams. Therefore, in order to develop a sound management scheme, it is essential to have a proper understanding of the receiving stream, or specifically, to have a background in hydrology, hydraulics, erosion/deposition processes, sedimentation engineering, stream responses, soil mechanics and related subjects. A better understanding of these subjects would assist in the development of practical design criteria for a range of stream protection methods. Moreover, criteria could be established based on the physical processes of stream and river responses. In other words, there is a need to incorporate "stream tolerance characteristics" into the management targets. This paper provides brief discussions about the shortcomings of this overly simplified approach. The paper also demonstrates that, with a proper knowledge of sedimentation engineering, practitioners can improve the design of structural measures for storm water management.

This article explains four general conclusions arrived at while developing information necessary for planning salmonid restoration in the Clearwater River sub-basin in Idaho. This article will summarize the reasoning behind the following conclusions: (1) Management and restoration activities need to be planned at a scale that captures the life history needs of target species and the ecosystem processes with which they interact; (2) ESA species restoration planning needs to occur within the framework that understands species' health as an interplay between biological productivity, ecosystem processes and habitat capacity; (3) Management will take place within an environment of uncertainty. An exhaustive scientific research program will not be developed independently of management activities. Decisions must be made now without the luxury of necessary information; and (4) The process itself is a form of outreach. The science is embedded in a social process that needs to be explicitly addressed or there will be little hope of acceptance of the assessment or implementation of the plan.

The CRCC Native American natural Resource Management Initiative is the "brain child" of Si Tanka College faculty member Mark Peacock. Peacock wrote a proposal for the combined classroom and field camp experience to the David and Lucille Packard Foundation in June 1998 when the college was still known as Cheyenne River Community College (CRCC). In 1999 the college adopted the name Si Tanka College in honor of the Lakota Chief Big Foot. The Packard Foundation funded the program for a one-year period for $100,000. The students participating in the program would begin the Total Maximum Daily Load (TMDL) process for the Moreau River.