Journal of Water Resources Planning and Management

WASP is a mass‐balance quasi‐simulation computer package developed to facilitate analysis of the performance of the head works and transfer components of a water supply system under different operating policies and changes to system configuration. Its generality is due to the use of a network linear program (LP) which allows system components to be connected in virtually any configuration. The user defines an operating policy in terms of easily understood rules which guide the network LP when it makes seasonal assignments of water within the water supply system. WASP is based on a network LP to take advantage of computer codes up to 100 times faster than standard LP codes. This paper discusses the principles used to formulate the network LP. It then presents a case study involving a complex urban water supply system to demonstrate the generality of WASP. Finally it reviews the input/output features of WASP which streamline its use.

Multicriterion decision‐making (MCDM) techniques are used to analyze a multiobjective wastewater management problem in order to select an appropriate management scheme. A specific case study consisting of 15 alternative management schemes is evaluated with respect to 12 noncommensurable, discrete criteria, using three different MCDM techniques; compromise programming (CP), cooperative game theory (CGT), and ELECTRE I. The case study is the Nogales International Wastewater Management Project, which treats wastewater coming from the twin cities of Nogales, Arizona and Nogales, Sonora, Mexico. The problem is formulated in a multicriterion context in terms of objectives, specifications, criteria, criterion scales, and construction of an evaluation matrix that consists of the alternative versus criteria array. Analyses of the matrix using the MCDM techniques result in selecting the most satisfying alternative in the case of CP and CGT and narrowing the choice to a few non‐dominated alternatives (here, two) in the case of ELECTRE I.

A study to determine the sensitivity of the unit hydrograph to the effects of the urbanization process was conducted. The overland flow parameter that defines the degree of urbanization in an urban watershed is the percentage of the total watershed area that is impervious. Furthermore, the parameter which defines the degree of urbanization in the channelized flow portion of a watershed is the channel roughness coefficient. Several rainfall‐runoff simulations were conducted in order to determine the hydrologic response of the unit hydrograph to the impact of urbanization. A hydrologic model was formulated for an urban catchment located at Houston, Texas, using the kinematic wave model developed by the Hydrologic Engineering Center (HEC). The model was used to simulate various degrees of urbanization by allowing the percentage of watershed imperviousness and the channel roughness coefficient to vary from simulation to simulation. A system of regression equations was developed to quantify the impact of urbanization on the unit hydrograph. The equations were incorporated into the A&M Watershed Model and verified by modeling three test watersheds.

Both theory and experience indicate that, while detention basins designed to control peak discharge are effective in controlling peak rates, the basins are ineffective in controlling the degradation of erodible channels downstream of the basin. The increase in runoff volumes that accompanies land development causes greater rates of channel degradation because of the increased duration of high in‐bank flow rates. While planning and design procedures are available for peak discharge control, there has been a need for similar methods for the control of channel erosion and water quality. A relationship for making planning estimates of the volume of detention storage required to control channel erosion is provided. A procedure that can be used for design is also provided. Planning and design methods for water quality control through detention time control are also provided. The importance of adopting multicriterion stormwater management policies is emphasized, with the policy recommending control of flooding, channel erosion, and detention time for water quality enhancement.

Soil erosion has long been a major problem to mankind and continues to threaten soil conservation worldwide. To deal effectively with this problem, the first step is to obtain a reasonably accurate prediction of the soil loss. This paper uses an inference procedure to combine soil loss predictions obtained from different methods. The objective of this combination is to minimize the uncertainty associated with the applied techniques. The procedure is applied to several cases to evaluate this procedure, and future developments are discussed. The procedure is performed satisfactorily in test routings on two Nebraska watersheds. A similar procedure will be used in erosion and runoff control evaluation.

Physiographic, hydrologic, and rainfall data from 18 small drainage basins in semiarid, central Wyoming were used to calibrate topological, unit‐hydrograph models for celerity, the average rate of travel of a flood wave through the basin. The data set consisted of basin characteristics and hydrologic data for the 18 basins and rainfall data for 68 storms. Calibrated values of celerity and peak discharges subsequently were regressed as a function of the basin characteristics and excess rainfall volume. Predicted values obtained in this way can be used as input for estimating hydrographs in ungaged basins. The regression models included ordinary least‐squares and seemingly unrelated regression. This latter regression model jointly estimated the celerity and peak discharge. The correlation between residuals of the celerity and peak‐discharge regressions was sufficiently large to de‐, crease the variances of estimated univariate‐model parameters.

An expert system is an efficient human‐computer system designed to automatically produce decisions that normally require the application of both factual and heuristic information by a human expert. Expert systems do not add inherent validity to the decision‐making process. They currently provide, however, the avoidance of errors in solution procedures arising from inexperience, fatigue, overconfidence, and other human factors. Information in expert systems is normally represented by production rules. In the development of an expert system two primary concerns are the development of the set of rules and the logic by which the information is processed to obtain a decision. Several approaches to the elicitation of rules, the logical structuring of rules and uncertainty, and calibration of expert systems are reviewed. Decisions resulting from the application of expert systems are very dependent on the logic structure of the system used. Little evidence exists to guide expert system developers in the selection of these approaches.