Journal of Water Resources Planning and Management

Western Terrebonne Parish, a low‐lying coastal marsh with numerous meandering bayous and small lakes, is located in south‐central Louisiana. The area is frequently inundated by backwater, tidal, and headwater floodings. An extension of the existing Avoca Island levee is proposed for further providing flood protection to the area. This paper evaluates the potential changes in the hydrologic regime and the area's hydrodynamics caused by the proposed levee extension. The study area is modeled as a network of junctions and channels. Riverine and tidal boundary conditions are used as input to a watershed model that predicts the time history of water level, flow, and sediment of the area. The response of the marsh to flooding events is simulated with both existing and future conditions. The results in terms of surface water contours, current discharge patterns, and sediment concentration distributions are presented. The changes before and after the levee extension are discussed.

The BRASS (basin runoff and streamflow simulation) model was developed to improve the real‐time and predictive determination of flood discharges and stages, and to aid in flood management decisions within the Savannah River system. BRASS is an interactive hydrologic/hydraulic model that combines aspects of continuous and event hydrologic simulation with dynamic streamflow routing, and represents a significant step in the evolution of flood forecasting and flood management techniques. Model datasets were developed for the three major multipurpose reservoirs in the Savannah River system. Practical considerations in development, calibration, verification, and application are discussed. Standard flood management procedures are compared to BRASS results, indicating a potential for improvement in the use of flood control storage, as well as the inaccuracy of hydrologic routing methods. In addition to real‐time water control management, the model has been successfully used in the analysis of flooding in coastal areas, spillway design and design flood operations for dams, emergency operations for dam failures, and the design of channel modifications for flood control.

Several models that can be used to optimally size water distribution pipes were applied to a hypothetical system. The results are summarized in this paper. The models produced solutions with costs that were within 10% of one another, although the solutions were quite different. While the models were helpful in sizing pipes, some manual calculations and a good deal of engineering judgment were required to apply them.

A methodology for identifying and prioritizing areas in Illinois for monitoring of hazardous substances in groundwater is described. The criteria used to determine monitoring priorities are the density of hazardous substancerelated commercial/industrial activity, the amount of current groundwater withdrawals for public water supply, the likelihood of future groundwater development through potential yield of sand and gravel and shallow bedrock aquifers, and the susceptibility of these aquifers to contamination. A computerized map overlay system is employed to differentiate prioritized areas throughout Illinois at a spatial scale of discrete United States Postal Service zip code units.

Increasing concentrations of carbon dioxide and other gases are expected to warm the earth several degrees in the next century, which would raise sea level a few feet and alter precipitation patterns. Both of these changes would have major impacts on the operation of coastal drainage systems. However, because sea level rise and climate change resulting from the greenhouse effect are still uncertain, most planners and engineers are ignoring the potential implications. Case studies of the potential impact on watersheds in Charleston, South Carolina, and Fort Walton Beach, Florida, suggest that the cost of designing a new system to accommodate a rise in sea level will sometimes be small compared with the retrofit cost that may ultimately be necessary if new systems are not designed for a rise. Rather than ignore the greenhouse effect until its consequences are firmly established, engineers and planners should evaluate whether it would be worthwhile to insure that new systems are not vulnerable to the risks of climate change and sea level rise.

A definition of the term “floodway” is suggested, considering historical perspective, and discussing often‐overlooked floodway functions that should influence floodway delineation. Rationales are presented for value judgments that might affect floodway delineation. Also emphasized is the importance to local governments of thorough assessment of multiple land and water needs and risks before making floodway delineation determinations.

A model called SWRRB (simulator for water resources in rural basins) was developed for simulating hydrologic and related processes in rural basins. The SWRRB model was developed by modifying the CREAMS (chemicals, runoff, and erosion from agricultural management systems) daily rainfall hydrology model for application to large, complex, rural, basins. The three major components of SWRRB are weather, hydrology, and sedimentation. Processes considered include surface runoff, return flow, percolation, evapotranspiration, transmission losses, pond and reservoir storage, sedimentation, and crop growth. SWRRB has been tested on 11 large watersheds from eight Agricultural Research Service (ARS) locations throughout the United States. The results show SWRRB can realistically simulate water and sediment yields under a wide range of soils, climate, land‐use, topography, and management conditions. SWRRB should provide a versatile and convenient tool for use in planning and designing water resources projects.

The use of embedding technique as a mechanism for coupling the simulation model of a particular groundwater system with an optimization model has been extended herein to multi‐aquifer systems. The combined management model is used to determine the optimal groundwater management schemes in a hypothetical multi‐aquifer system under transient and steady state conditions. The model enables the determination of optimal allocation of wells in different aquifers and their pumping rates to achieve a system‐wide maximum head distribution while satisfying the water production targets, well capacity restrictions, and lower bounds on hydraulic heads at critical points. Constraint and weighting methods of the multiobjective programming techniques are used to develop trade‐off curves relating the sum of hydraulic heads in the whole system as well as in individual aquifers at various water production targets. The generated trade‐off curves may enhance the decision maker's ability to select the best development policy from a set of alternative policies by considering other technological, financial, and legal constraints.

Public policies in the Great Lakes have traditionally developed in an ad hoc manner as specific issues occurred. Recently, the transboundary pollution problems have caused this historical approach to become inadequate. Key policy issues now are acid rain, water quality, and lake levels and quantity. These policy issues were examined to help define research needs in the atmospheric and hydrospheric sciences so as to help resolve future policy issues. However, policy development and in‐depth documentation of policies are needed for the Great Lakes to enable development of sound research agenda.

An approach to establishing priorities for future flood control planning has been developed and applied to hydrologic subbasins in New Jersey. Data on historical flood losses, flood potential, and current and prior flood control planning efforts were compiled and entered into a flood control data base, accessed through a computer data base management system. The selection of indicator variables, characterizing flood control planning needs, is considered, along with a system of ranking and weighting these variables for assignment of planning priority numbers to the subbasins. This approach is concluded to provide an adequate screening mechanism for establishing an initial list of planning candidates, although more subjective factors must then be used for further evaluation.

Two simple numerical models adopted for microcomputer applications and used to analyze groundwater problems are described. The alternating direction implicit method is an iterative procedure used to model relatively large two‐dimensional aquifers on microcomputers. The direct solution model uses a checkerboard numbering pattern of the grid elements to reduce the number of continuity equations and solves the remaining equations simultaneously. The analysis of a water barrier and recovery system for a petroleum products terminal is presented in the paper, and the computation times for both models are compared using IBM, AT&T, and HP microcomputers.

Recently, calcium magnesium acetata (CMA) was identified by the Federal Highway Administration as a potentially suitable, noncorrosive road deicer substitute for sodium and calcium chloride. Research on the environmental effects of CMA has principally dealt with the effects of CMA on plant life and water quality in areas surrounding points of deicer application. However, in urban areas served by combined storm/sanitary sewer systems, most road deicing material is washed into the sewer system and, therefore, passes through the publicly owned treatment works (POTW). Because of the chemical nature of CMA, significant increases in organic loadings to POTW may result. The purpose of this technical note is to delineate potential adverse effects of CMA application on POTW operation, based on theoretical considerations and past collected runoff data for conventional deicing salts. The city of Buffalo, New York, is used as an example.