摘要:

The U.S. Water Resource Council has twice recommended that regional or multi‐site recreation economic models be relied on in place of single site models. This recommendation is evaluated by developing the advantages and disadvantages of different types and sizes of Regional demand models relative to water resources planning issues needing to be addressed in benefit cost analyses. The accuracy of use and benefit estimates of two different sized regional travel cost method demand models is compared with benefit estimates from single site travel cost and contingent value methods estimates. The results indicate that regional or large multi‐site demand models may not be as cost effective or as accurate as single site models in answering simple resource issues such as benefits of an existing site. For planning issues dealing with evaluation of the benefits of building a new recreation site or improving quality at an existing site, the regional approach is desirable, howe

ISSN:0043-1397    

DOI:10.1029/WR022i004p00431

年代:1986

数据来源: WILEY

摘要:

Exchange through markets is one way of allocating water. In many settings this method possesses a number of desirable attributes to a greater degree than alternative allocative mechanisms: flexibility, security, predictability, fairness …. Markets have shortcomings, too, especially related to quantity and quality return flow effects, but these can be mitigated through changes in the administrative framework of the water rights system. It is shown that an economically efficient water allocation system must integrate quantity and quality management and would be neither a priority nor a proportional rights system. However, the nature of the water rights system may not be very important if short‐term rental markets are operative. The potential for intrastate and interstate water markets is discus

ISSN:0043-1397    

DOI:10.1029/WR022i004p00439

年代:1986

数据来源: WILEY

摘要:

A methodology is developed for determining optimal pumping and recharge of large scale artesian and/or nonartesian aquifers. This methodology couples optimization techniques with existing groundwater simulation models. It can be applied to both groundwater policy evaluation (allocation) such as large‐scale aquifers and to hydraulic management problems such as the dewatering of mining or excavation sites. The state variables which represent the heads and the control variables which represent the pumpages are implicitly related through the groundwater simulator. The simulator equations are used to express the states in terms of the controls, yielding a much smaller reduced problem. Techniques for computing gradients of reduced problem functions are described. The reduced problem is solved by combining augmented Lagrangian and reduced gradient procedures. The optimization‐groundwater simulation system is referred to as GWMAN. Two small examples are solved in addition to both steady state and transient type dewatering problems. Also, an application to the Edwards Aquifer in Texas is presen

ISSN:0043-1397    

DOI:10.1029/WR022i004p00447

年代:1986

数据来源: WILEY

摘要:

With the methodology recommended by Baumol and Oates, comparable estimates of wastewater treatment costs and industry outlays are developed for effluent standard and effluent tax instruments for pollution abatement in five hypothetical organic petrochemicals (olefins) plants. The computational method uses a nonlinear simulation model for wastewater treatment to estimate the system state inputs for linear programming cost estimation, following a practice developed in a National Science Foundation (Research Applied to National Needs) study at the University of Houston and used to estimate Houston Ship Channel pollution abatement costs for the National Commission on Water Quality. Focusing on best practical and best available technology standards, with effluent taxes adjusted to give nearly equal pollution discharges, shows that average daily treatment costs (and the confidence intervals for treatment cost) would always be less for the effluent tax than for the effluent standard approach. However, industry's total outlay for these treatment costs, plus effluent taxes, would always be greater for the effluent tax approach than the total treatment costs would be for the effluent standard approach. Thus the practical necessity of showing smaller outlays as a prerequisite for a policy change toward efficiency dictates the need to link the economics at the microlevel with that at the macrolevel. Aggregation of the plants into a programming modeling basis for individual sectors and for the economy would provide a sound basis for effective policy reform, because the opportunity costs of the salient regulatory policies would be captured. Then, the government's policymakers would have the informational insights necessary to legislate more efficient environmental policies in light of the wealth distribution effects.

ISSN:0043-1397    

DOI:10.1029/WR022i004p00467

年代:1986

数据来源: WILEY

摘要:

A point rainfall generator is a probabilistic model for the time series of rainfall as observed in one geographical point. The main purpose of such a model is to generate long synthetic sequences of rainfall for simulation studies. The present generator is a continuous time model based on 13.5 years of 10‐min point rainfalls observed in Belgium and digitized with a resolution of 0.1 mm. The present generator attempts to model all features of the rainfall time series which are important for flood studies as accurately as possible. The original aspects of the model are on the one hand the way in which storms are defined and on the other hand the theoretical model for the internal storm characteristics. The storm definition has the advantage that the important characteristics of successive storms are fully independent and very precisely modelled, even on time bases as small as 10 min. The model of the internal storm characteristics has a strong theoretical structure. This fact justifies better the extrapolation of this model to severe storms for which the data are very sparse. This can be important when using the model to simulate severe flood event

ISSN:0043-1397    

DOI:10.1029/WR022i004p00475

年代:1986

数据来源: WILEY

摘要:

The planning of reservoir operation presents decision makers with a trade‐off between competing functions, which are energy production and flood control in this study. To optimally resolve the trade‐off between maximization of energy revenues and minimization of downstream losses, the interaction between the expected value and variance of revenues (accruing from the reservoir operation) is included in a stochastic daily reservoir operation planning model. By parametrically varying the expected value and variance of the objective function, the risk‐averse nature of decision makers is incorporated, resulting in a range of feasible alternative policies that reflect the decision maker's attitude toward revenue maximization and poor performance of the reservoir oper

ISSN:0043-1397    

DOI:10.1029/WR022i004p00483

年代:1986

数据来源: WILEY

摘要:

Reliability in water supply reservoir operation is commonly thought of as the probability of failing to achieve some target release. Here we explore two additional proposed descriptions of reservoir performance: the maximum shortfall from the target (system vulnerability) and the maximum number of consecutive periods of deficit during a record (system resilience). The larger the maximum shortfall, the greater the vulnerability. The shorter the maximum length of deficits, the more resilient the system. Using multiobjective mixed‐integer, linear programming, the tradeoffs between reliability, vulnerability, and resilience are examined. It is found that as reliability is increased or as the maximum length of consecutive shortfalls decreases (resilience increases), the vulnerability of the water system to larger deficits increase

ISSN:0043-1397    

DOI:10.1029/WR022i004p00489

年代:1986

数据来源: WILEY

摘要:

Linear estimation has found many applications in the inference of spatial functions in surface and subsurface hydrology. The effect of parameter uncertainty is examined in a Bayesian framework with emphasis on the derivation of the Bayesian distribution (and its first two moments) of unknown quantities given some measurements. This distribution accounts not only for natural variability but also for parameter uncertainty. For known covariance parameters the Bayesian distribution is Gaussian (for Gaussian processes) with the mean being a given linear function of the data. This linear estimator is equivalent to the conventional Gaussian conditional mean estimator for a priori known drift coefficients and is the same with kriging for diffuse prior distribution of the drift coefficients; however, the developed procedure is more general. When both drift and covariance function parameters are uncertain, the Bayesian distribution is generally not Gaussian, and the Bayesian conditional mean is a nonlinear estimator. The case of diffuse priors is examined in some detail; it is shown that the posterior distribution of the covariance function parameters is given by the restricted likelihood function, i.e., the likelihood function of generalized increments. The results provide insight into the applicability of maximum likelihood versus restricted maximum likelihood parameter estimation, and conventional linear versus kriging estimation. A more general procedure which includes these methods as special cases is presented.

ISSN:0043-1397    

DOI:10.1029/WR022i004p00499

年代:1986

数据来源: WILEY

摘要:

Solutions are obtained with the Laplace transform technique for four cases related to radionuclide transport from an injection well to a fractured porous formation. The four cases are described by two models (models I and II). Each model is solved for two different boundary conditions at the well bore, namely, a constant concentration or an exponentially decaying concentration relationship. Model I assumes that radionuclides are transported through the fracture by radial advection and longitudinal dispersion, while model II assumes radial advection only. In both models, attenuation mechanisms, such as radioactive decay and adsorption of linear equilibrium isotherms, are considered in the fracture as well as in the porous rock. Transport from the fracture to the surrounding porous rock is accounted for by molecular diffusion. Analytical solutions of concentration distributions valid for small‐time periods and for steady state are obtained for model I; solutions at intermediate and large time intervals are determined by inverting the appropriate Laplace transform equations with the Stehfest method. Analytical solutions of concentration distributions for the transient (valid for any specific time) and steady state conditions are given for model II. These two boundary conditions at the well bore may lead to significant discrepancies in calculated concentration distributions for large injection time periods, but they yield essentially the same results for short injection periods. As shown by a sample problem, computational results of models I and II converge at large injection time periods, indicating that the effect of longitudinal dispersion on the transport of radionuclides may be unimportant at long injection periods. When subjected to Taylor's dispersion theory, it is found that model I can be reduced to the conventional one‐dimensional advection‐dispersion model involving radionuclide transport through a fracture in which the groundwater velocity is con

ISSN:0043-1397    

DOI:10.1029/WR022i004p00508

年代:1986

数据来源: WILEY

摘要:

As part of the investigation of groundwater contamination at a uranium‐scrap recovery plant at Wood River Junction, Rhode Island, laboratory experiments led to the development of a model for predicting the transport of strontium 90 in glacial outwash sediments based on an approximate mechanism for ion exchange. The multicomponent system was simplified to two components by regarding all exchangeable cations other than strontium 90 as a single component. The binary ion‐exchange parameter was a function of the variable, total ion concentration. A one‐dimensional solute transport model was formulated to evaluate the time necessary for natural groundwater flow to remove the strontium 90 contamination plume from the groundwater system to the Pawcatuck River. The finite difference transport equations were solved sequentially for total ion concentrations, then strontium 90 concentrations. Clay‐free quartz and feldspar sands at the study site have little potential for strontium 90 sorption, and high calcium, magnesium, and sodium concentrations compete for the few ion exchange sites. As the total ion concentration plume moves out of the system, ion exchange of strontium 90 increases, reducing the strontium 90 concentration in the groundwater. Cleanout times predicted using the binary ion exchange mechanism were about two thirds of those predicted using a constant distribution coefficient. It is suggested that this type of model can simulate solute transport more realistically in many groundwater systems where the total ion concentration is not c

ISSN:0043-1397    

DOI:10.1029/WR022i004p00519

年代:1986

数据来源: WILEY