摘要:

This paper presents a pilot study of a method for finding an approximation for the optimal policy of a dynamic system which depends on stochastic state variables. The systems being considered are multi‐reservoir water supply systems whose (stochastic) state variables are the quantities of water in each reservoir and some previous inflows which affect future inflows. Of special importance is the three‐reservoir system which represents the major part of Israel's water supply system: Lake Kinneret and two underground aquifers. This system can be represented by five stochastic state variables: the quantities of water in each of the three reservoirs and the inflows into the Kinneret for the two previous months. Since this system is too large to be solved by the usual dynamic programing approach, a method was devised in this study for obtaining an approximate solution which does not consume too much time or space. This method will be referred to as the parameters iteration method. It has been tested on a smaller system which contains only three stochastic state variables: the amount of water in the Kinneret and two previous monthly inflows. The results were satisfactory in the sense that the approximate solution obtained by this method was as good as the optimal solution obtained by a dynamic programing approach to this problem. Thus it can be expected that the parameter iteration method would be efficient for the three reservoir problems as well and for larger probl

ISSN:0043-1397    

DOI:10.1029/WR015i004p00737

年代:1979

数据来源: WILEY

摘要:

A branch‐and‐bound method for use in planning regional wastewater treatment systems is extended to include a methodology for generating and evaluating alternative plans. Since many planning issues are related to a specific configuration of regional facilities, economic trade‐offs among alternative plans are evaluated using imputed values of individual facilities or groups of them. The imputed values, or bounds on them, are calculated from information contained in the branch‐and‐bound tree using an ‘imputed value incidence matrix.’ The general approach, which can be applied to other public facility location problems, is designed to aid an analyst in gaining more insights into the problem under study than obtainable from conventional optimization methods. The procedure is designed for use within a larger planning process where the steps are to generate, to evaluate, and to elaborate on alternative plans. The method is illustrated using the regional wastewater system for DuPage Cou

ISSN:0043-1397    

DOI:10.1029/WR015i004p00750

年代:1979

数据来源: WILEY

摘要:

The New England River Basins Commission has utilized communication strategies designed to stimulate public involvement in the planning process of three ‘level B’ studies. The effectiveness of these strategies, including agency‐produced printed information, use of the mass media, personal staff contact, and public meetings has been evaluated by means of questionnaires administered to members of the public who attended the final public meetings conducted in each study. The implications of the research findings for more effective functioning of citizen participation programs are disc

ISSN:0043-1397    

DOI:10.1029/WR015i004p00757

年代:1979

数据来源: WILEY

摘要:

Residential water demand is estimated as a function of temperature, rainfall, house value, water price, and household size using monthly cross‐section and time‐series meter readings from 261 residential households in Raleigh, North Carolina, between May 1969 and December 1974. Tests for validity of assumptions are made, and a methodological approach is used that provides unbiased estimates of parameters and standard errors with data that exhibit serially correlated residuals. Demand relations are estimated for total residential, winter, and sprinkling demands. Sprinkling use per period per customer for each year is estimated by subtracting winter (November–April) from summer (May–October) use. Household size explained the largest proportion of the variation in the data. Estimated sprinkling demand was found to be highly responsive to changes in water price and the level of the climatic variables, while total residential demand and winter demand were less responsive to price

ISSN:0043-1397    

DOI:10.1029/WR015i004p00763

年代:1979

数据来源: WILEY

摘要:

A procedure for helping analysts to choose the objectives and uncertainties to be considered in the evaluation of alternative system designs has been developed. Two models are described, one for screening system attributes (and their related objectives) and one for screening uncertainties about the levels of these attributes. The models use first‐order estimates of utilities and probabilities to calculate a measure of the maximum expected effect on the results of the evaluation of not considering an objective or of assuming certainty, rather than uncertainty, about the levels of an attribute. The models are applied to the problem of planning a hypothetical multipurpose dam and reservoir syste

ISSN:0043-1397    

DOI:10.1029/WR015i004p00768

年代:1979

数据来源: WILEY

摘要:

Although many indices of drainage basin characteristics have been devised and employed in previous studies, there is still a need to identify those indices which have an easily interpreted physical significance to be of use in explanatory models. Whereas stream power has been used in hydraulic studies of river channels, a comparable expression can be developed to denote the potential energy available in the stream network of a drainage basin. An index of drainage network power is obtained as the volume of the channel network divided by the basin relief and this index expresses the potential energy of the network of channels in the basin and it may be directly related to flood potential. The index is used in a study of 14 basins in Britain and it correlates well with mean annual flood obtained from a partial duration series.

ISSN:0043-1397    

DOI:10.1029/WR015i004p00775

年代:1979

数据来源: WILEY

摘要:

Stochastic dynamic programming (DP) is used to find the operating policy with the least expected steady state cost for a water supply system consisting of a reservoir and an alternative source. The set of possible decisions consists of a number of release rules, each expressing release as a function of storage, rather than a number of discrete releases, as in the conventional DP approach. A flexible procedure is developed which permits inflow to be described by piecewise linear probability density functions, and removes the constraint that inflow and release must be multiples of the discrete unit of storage. The techniques are applied to a reservoir‐river system, and through simulation, the results are compared with the solution found by conventional D

ISSN:0043-1397    

DOI:10.1029/WR015i004p00778

年代:1979

数据来源: WILEY

摘要:

Bulk precipitation contributes significant quantities of cations and trace metals to a subalpine catchment located in the North Cascade Range of Washington. Precipitation loadings account for 30% of the major and more than 50% of the minor element export from the catchment. Preliminary data from larger basins in the North Cascades suggest similar values. Calcium and potassium measured in bulk precipitation are largely derived from continental dusts, while sodium and magnesium originate as marine aerosols. Lead, copper, and arsenic, products of anthropogenic activity in the Puget Lowland, are deposited downwind in the Cascade Mountains; mean precipitationpH at the study site was 4.85 during 1974 and 1975. Elements contributed by precipitation become part of complex upland biogeochemical cycles. With the exception of highly mobile ions like sodium, elemental levels in streamflow reflect biologic and pedogenic cycling processes rather than direct precipitation influence.

ISSN:0043-1397    

DOI:10.1029/WR015i004p00787

年代:1979

数据来源: WILEY

摘要:

A 0.3028‐ha watershed has been instrumented to monitor streamflow and subsurface flow through the soil mantle at a variety of topographic locations. The watershed is forested, with steep (35°) slopes and shallow (average 55 cm) soils on impermeable Old Man gravels. Data for a number of storms indicate that subsurface flow via ‘macropores’ (root channels, pipes) and seepage zones in the soil is the predominant mechanism of channel stormflow generation in storms with quickflows greater than about 1 mm. Subsurface flow from all parts of the watershed appears to contribute to stormflow even in very small storms (quickflow of the order of 3% of net precipitation). The saturated hydraulic conductivity of the soil matrix is not a limiting factor on the ability of subsurface flow to generate channel stormflow, because dye tracer experiments demonstrate that water may move through macropores (particularly root channels) at rates 2 orders of magnitude greater. However, subsurface flow from lower slope areas contributes to delayed flow; cessation of subsurface flow and Streamflow after a drought period is roughly coincident in time. In the study area it appears that streamflow is at almost all times dominated by subsurface flow and that runoff from partial and variable source areas contributes significant quantities of streamflow only during the rising limb of small (less than 1 mm of quickflow) flood hydro

ISSN:0043-1397    

DOI:10.1029/WR015i004p00795

年代:1979

数据来源: WILEY

摘要:

Reservoir operation objectives are considered by maximizing an objective function while maintaining various minimum values of a second objective in an optimization constraint. This is often referred to as the ϵ‐constraint approach; a priori estimates of objective worth are thereby eliminated. The constrained optimizations are repeated for many synthetic sequences of inputs to evaluate the risk associated with attainment of one objective for a given value of another objective. A trade‐off level for design of the reservoir operation rule is then subjectively selected based upon consideration of objective trade‐offs and their risks. An operation rule is estimated from the optimum decision set associated with the selected trade‐off level, by using Implicit Stochastic Optimization methods already available. These techniques are applied to the practical problem of the Coralville reservoir, near Iowa City, Iowa, for flood control and recreation operating purposes and resulting operation rules are compared to the existing operat

ISSN:0043-1397    

DOI:10.1029/WR015i004p00807

年代:1979

数据来源: WILEY