摘要:

An optimization model that may be used by reservoir system operators to improve daily, real‐time operations and to evolve better long‐term operating guidelines is developed and tested. The four multipurpose reservoirs in the Green River Basin (GRB) of Kentucky are used as a case study. The GRB Operation Optimization Model (GRBOOM) is a linear program constructed to imitate the decision‐ making process that results in actual reservoir release decisions. The model is easily modifiable and very flexible, which allows sensitivity analysis and experimentation with new operating guidelines. This experimentation should permit the operators to evolve improved operating policies. The inputs to the model are data that are readily available, and the outputs may be presented in easily interpreted graphical

ISSN:0043-1397    

DOI:10.1029/WR019i001p00001

年代:1983

数据来源: WILEY

摘要:

A joint reservoir control‐capacity expansion problem is considered in which the expansion policy is required to be deterministic. Since this problem is difficult to solve, because the release policy is stochastic, a heuristic procedure is proposed, which utilizes an upper bound to the optimal deterministic solution obtained by solving a modified stochastic problem and a simple averaging heuristic for transforming stochastic policies into deterministic policies. A simple numerical example demonstrates the overall procedur

ISSN:0043-1397    

DOI:10.1029/WR019i001p00015

年代:1983

数据来源: WILEY

摘要:

A linear programing model is used to evaluate the economic feasibility of reducing phosphorus loads from cropland to levels that are expected to alter adequately the trophic conditions of a water supply reservoir. The model employs phosphorus buffer curves for distributing phosphorus losses between runoff and eroded soil. Phosphorus pollution reductions are estimated for conservation activities according to the amount of erosion control and phosphorus fertility status. The planning model is intended to provide the best available estimates of pollution control attainable with given budget outlays, as well as to allocate pollution control funds efficiently among watersheds. It also contains sufficient detail to suggest practices for each local soil that are consistent with water quality plans.

ISSN:0043-1397    

DOI:10.1029/WR019i001p00021

年代:1983

数据来源: WILEY

摘要:

An algorithm is presented to introduce real time streamflow forecasts in reservoir operation. The adaptive control technique can handle situations where stream flow transition probabilities and system objectives are continuously updated and changing over finite transient periods before achieving steady state conditions. As a case study, streamflow forecasting and adaptive control are used in the High Aswan Dam, Egypt, to minimize losses due to irrigation deficits, power production deficits, and flood damages. Results are extensively compared to those obtained using a traditional steady state stochastic dynamic programing approach and those obtained using the heuristic operational policy of High Aswan Dam.

ISSN:0043-1397    

DOI:10.1029/WR019i001p00033

年代:1983

数据来源: WILEY

摘要:

Compliance in Maryland with the Federal Clean Water Act will cost an estimated $3 billion. By charging a modest water/sewage fee for residential water use ($2 per thousand gallons), it is shown that sewage flows could be reduced, resulting in a compliance cost savings of $21 million. The cost reduction occurred even though only one third of the municipalities (heavy per capita water users) had to bear the increased price. Pricing policies are suggested as a method of reducing the costs of environmental standards.

ISSN:0043-1397    

DOI:10.1029/WR019i001p00053

年代:1983

数据来源: WILEY

摘要:

Field measurements of CCl3F and CCl2F2in groundwater have shown that concentrations in recharge areas are often higher than those in water at equilibrium with the atmosphere. Sorption and desorption of these fluorocarbons from soil surfaces in response to changes in soil moisture may be responsible for this enrichment. Soil slurry experiments were performed to determine whether concentrations of aqueous fluorocarbons increased when water came into contact with dry soils. The aqueous concentrations of CCl3F increased by a factor of 83–981% after mixing water with soils. Concentrations of CCl2F2in water increased over a range of 34.6–144% for six slurries and decreased in two slurr

ISSN:0043-1397    

DOI:10.1029/WR019i001p00057

年代:1983

数据来源: WILEY

摘要:

A mathematical model is presented which describes the salt water–fresh water motion with a sharp interface, assuming the validity of the Dupuit approximation. This model is used as a base to derive a numerical model (finite difference method) which is unconditionally convergent and stable. A method for solving the equations is selected together with a convergence accelerating procedure. The treatment of the boundary conditions in the interface is discussed, and a general and automatic solution for that problem is presented. Several tests with analytical solutions have been performed with good result

ISSN:0043-1397    

DOI:10.1029/WR019i001p00061

年代:1983

数据来源: WILEY

摘要:

The transition probability matrices which result from the Lloyd model of storage are very large, and when these matrices are constrained to be of manageable size, loss of accuracy in the performance of the model results. A description is given of an extension to a previous technique, the divided interval scheme, which makes possible the practical use of Markov chain analysis with given inflow distributions to provide comparatively accurate results in a probabilistic account of reservoir behaviour. The extension is applied specifically to the Lloyd model of storage for single reservoirs, and the results of such analyses are obtained with modest computer storage requirements.

ISSN:0043-1397    

DOI:10.1029/WR019i001p00069

年代:1983

数据来源: WILEY

摘要:

Seawater and fresh groundwater were made to flow through columns filled with samples from a ‘good aquifer’ that contained 5% or less clay minerals. Hydraulic conductivities decreased very sharply whenever seawater was flushed by fresh groundwater. The extent of the decrease depended mainly on the percentage of clays and reached maximum values of 10−1to 10−3of the original hydraulic conductivity. Subsequent flushing with seawater restored hydraulic conductivity only in a slight measure, if at all. The mechanism of this process was investigated by using CaCl2and NaCl solutions with the ionic strengths of seawater and fresh groundwater. It appears that the decrease of hydraulic conductivity is caused by an incipient stage of gel formation. The small water‐clay configurations that are formed during this stage behave as practically rigid particles and close the bottlenecks between adjacent pores. The major implications of these findings for groundwater hydrology are as follows: (1) In natural coastal aquifers the seawater‐freshwater interface is likely to undergo shifts on a semigeologic time scale. If the aquifer contains even a small percentage of clays, these shifts may create an almost impermeable boundary in the zone of the interface. Hitherto existing theories on movements of the interface regard permeability as constant. (2) The attempt to repel a fresh water‐seawater interface by the injection of fresh water may create a practically impermeable boundary within a relatively short time, and thus defeat it

ISSN:0043-1397    

DOI:10.1029/WR019i001p00077

年代:1983

数据来源: WILEY

摘要:

A procedure for solving the differential groundwater flow equation is presented herein. Using a finite difference or finite element discretization scheme, a set of simultaneous linear equations is obtained. The eigenvalues and eigenvectors of a matrix, which is a function of the coefficients of the set, are the key to the solution. A vectorLis obtained straightforwardly by combining the eigenvector matrixA, the eigenvalue vector α, the pumping vectorP, and the initial head vectorH. VectorL, which depends on time, can be expressed simply and explicitly as a function of the eigenvalues. Piezometric heads can be obtained by combiningAandL.Lis the only vector that needs to be computed asPchanges with time. In this way, influence functions of a piezometric head, flow velocity and flow depletion of a stream connected with the aquifer under a unit stress, can be obtained explicitly and continuously in time. The method can be applied to confined as well as to leaky aquifers and to one‐, two‐, or three‐ dimensional linear models. Its main advantage lies in the fact that it is unnecessary to repeatedly solve a matrix for every time increment. The method is particularly useful for groundwater management problems in which a large number of alternatives have to be eva

ISSN:0043-1397    

DOI:10.1029/WR019i001p00087

年代:1983

数据来源: WILEY