摘要:

Water resource development is commonly associated with hardware components, of the water supply system and not the existing institutions and established arrangements. In this paper we inquire into the social cost of the institutional arrangements existing in Israel's water economy, quantify the potential of institutional changes, and assess their capacity to compete with projects aimed at the development of “new” resources. The present situation is examined against situations which might have evolved should institutional barriers be relaxed using a linear programming model of Israel's water supply and farming systems in the various regions and social strata. The findings presented demonstrate the low economic cost of the institutional alternative relative to that provided through new resource developm

ISSN:0043-1397    

DOI:10.1029/WR023i001p00001

年代:1987

数据来源: WILEY

摘要:

Given an imperfect forecast of the total runoff volume for a season, it is useful to determine the distribution of the forecasted runoff volume in each subperiod. A method is developed for deriving the joint distribution of the subperiod flows and the total seasonal forecast. Historical subperiod flows and the corresponding total seasonal forecast are transformed to the Gaussian domain via three‐parameter lognormal transformations. The transformed subperiod flows and total seasonal forecast are then modeled as multivariate normal, from which the conditional distribution of the runoff volume in each subperiod, given the total seasonal forecast, is obtaine

ISSN:0043-1397    

DOI:10.1029/WR023i001p00009

年代:1987

数据来源: WILEY

摘要:

A system identification methodology for distributed‐parameter model building is described and compared with other methodologies for the modeling of groundwater reservoirs. The methodology is then applied to the analysis of New Zealand's Hutt Valley‐Port Nicholson groundwater reservoir data. It is established that there are too few measurement wells to allow for the identification of a model suitable for forecasting reservoir performance. Application of the methodology does, however, indicate where additional wells should be drilled, so that such a model could be identified. Certain field parameters are identified to within 100%, and this accuracy is found to be acceptable, provided all the important features of the reservoir are represented in the mo

ISSN:0043-1397    

DOI:10.1029/WR023i001p00015

年代:1987

数据来源: WILEY

摘要:

In this paper we consider a time series model which can easily be used for simulating stationary river flow sequences with high skewness and the long‐term correlation structure of an ARMA(1, 1) model. The model is fitted to monthly streamflows taken from a river in Malaysia. The simulated data bear a close resemblance to the historical sequence in terms of the mean, variance, skewness, and autocorrelation coefficient

ISSN:0043-1397    

DOI:10.1029/WR023i001p00032

年代:1987

数据来源: WILEY

摘要:

A new framework for modeling large‐scale transient unsaturated flow systems in spatially variable soils is proposed in order to overcome the problem of limited information about the local details of spatial soil variability. A stochastic approach, which assumes that local soil properties are realizations of three‐dimensional random fields, is followed for derivation of a large‐scale model representation (structure). The three dimensionality of the local flow and the nonlinear dependence of the local flow output on the local soil properties are considered. The large‐scale model structure is derived by averaging the local governing flow equation over the ensemble of realizations of the underlying soil property random fields. The resulting mean model representation is in the form of a partial differential equation in which averaged or effective model parameters occur. These effective model parameters (i.e., effective hydraulic conductivity and effective specific moisture capacity) are evaluated using a quasi‐linearized fluctuation equation and a spectral representation of stationary processes. The large‐scale model representation considers the large‐scale effects of soil property variability and has relatively few parameters. The general conclusions of this study are that soil property variability produces large‐scale hysteresis and anisotropy of the effective parameters. The potential theoretical and practical ramifications of these results in the area of unsaturated flow modeling need to be investigated. The general stochastic modeling framework developed here is applicable not only to unsaturated flow but also to other distributed parameter systems (e.g., saturated flow and transport, geothermal and oil rese

ISSN:0043-1397    

DOI:10.1029/WR023i001p00037

年代:1987

数据来源: WILEY

摘要:

The capillary tension head variance, the mean soil moisture content, and the effective specific soil moisture capacity are evaluated in the case of transient unsaturated flow in stratified soils using a three‐dimensional stochastic approach. The large difference in the correlation scales in stratified soils simplifies the related stochastic equations, allowing for analytical evaluations and derivation of generic expressions. Simplified asymptotic expressions, valid at particular ranges of the soil property and the mean flow characteristics, are also derived. Examples applying the theoretical results to two real soils are presented. It was found that the capillary tension head variance, the mean soil moisture content, and the effective specific soil moisture capacity show a large‐scale hysteresis which is due to spatial variability of the local hydraulic soil properties rather than to hysteresis in the local parameters. A companion paper shows that the effective hydraulic conductivities also show hysteresis produced by spatial soil variability. Such large‐scale hysteresis is mathematically, physically, and intuitively plausible. This may suggest that the hysteresis observed in laboratory or field experiments is, at least partly, due to soil variability rather than pore scale effects. This could be anticipated since spatial variability is the rule rather than the exception and it exists even in small‐scale expe

ISSN:0043-1397    

DOI:10.1029/WR023i001p00047

年代:1987

数据来源: WILEY

摘要:

The effective hydraulic conductivities of transient unsaturated flow in stratified soils are evaluated using a three‐dimensional stochastic approach. Because of the disparity of the correlation scales in a stratified soil, the general stochastic equations are simplified, and this allows analytical evaluation and derivation of generic expressions for the effective hydraulic conductivities. Simple asymptotic expressions, valid at particular ranges of the soil property and the mean flow characteristics, are also derived. Several examples illustrating the results using data from two real soils are also presented. It was found that the effective hydraulic conductivities show significant hysteresis and are anisotropic with a degree of anisotropy depending on the mean flow conditions (wetting or drying). Such hysteresis and anisotropy are produced by the spatial variability of the hydraulic soil properties rather than hysteresis or anisotropy of the local parameters. A physical interpretation of the results is given along with a qualitative comparison with field observations. The ramifications of this study need to be further investigated and be considered in field applications such as waste disposal contro

ISSN:0043-1397    

DOI:10.1029/WR023i001p00057

年代:1987

数据来源: WILEY

摘要:

Upon well recharge of aerobic water into an anaerobic aquifer a number of redox and dissolution reactions occur. In these redox reactions sulfides and organic material are oxidized by oxygen and nitrate present in the recharge water. Acid, produced during these redox reactions, is neutralized by calcium carbonate present in the aquifer and by the hydrogen carbonate‐carbon dioxide equilibrium. Sulfides, organic material, and calcium carbonate are present in finite quantities in the aquifer. Therefore these processes will terminate after some time, and an aerobic zone will spread around the recharge well. These geohydrochemical reactions have major consequences for a system consisting of separate recharge and discharge wells with respect to the clogging of the discharge wells and to the treatment of the abstracted water to drinking wate

ISSN:0043-1397    

DOI:10.1029/WR023i001p00069

年代:1987

数据来源: WILEY

摘要:

The potential benefits of basinwide groundwater management in agricultural areas are analyzed with an optimization model. The model incorporates functions to compute spatial and temporal groundwater responses to hydraulic stresses, net agricultural revenues as a function of water use, and groundwater recharge from individual stream reaches. Stream recharge is computed on the basis of both groundwater elevations and the amount of streamflow. The model can be run either to maximize basinwide net revenue over a planning period or to simulate private optimization by individual agricultural sectors. The effects of several hydrologic factors on the benefits of basinwide groundwater management are estimated by comparing model results for conditions in the Salinas Valley in California prior to reservoir construction with a number of other hydrologic scenarios. Results indicate that basinwide groundwater management and reservoir operation may be close substitutes for each other under certain conditions, that an interesting relationship appears to exist between the potential benefits of groundwater management and the annual amount of streamflow available for recharge, and that consideration of stochastic variations in streamflow is unnecessary in the analysis of systems relying primarily on groundwater. A framework is also presented for identifying strategies that meet environmental constraints while minimizing the revenue losses to current water users. For all scenarios considered, basinwide groundwater management generates larger revenues than private optimization while using considerably less water.

ISSN:0043-1397    

DOI:10.1029/WR023i001p00077

年代:1987

数据来源: WILEY

摘要:

The contributions of this work are twofold. First, a methodology for estimating the elements of parameter matrices in the governing equation of flow in a confined aquifer is developed. The estimation techniques for the distributed‐parameter inverse problem pertain to linear least squares and generalized least squares methods. The linear relationship among the known heads and unknown parameters of the flow equation provides the background for developing criteria for determining the identifiability status of unknown parameters. Under conditions of exact or overidentification it is possible to develop statistically consistent parameter estimators and their asymptotic distributions. The estimation techniques, namely, two‐stage least squares and three stage least squares, are applied to a specific groundwater inverse problem and compared between themselves and with an ordinary least squares estimator. The three‐stage estimator provides the closer approximation to the actual parameter values, but it also shows relatively large standard errors as compared to the ordinary and two‐stage estimators. The estimation techniques provide the parameter matrices required to simulate the unsteady groundwater flow equation. Second, a nonlinear maximum likelihood estimation approach to the inverse problem is presented. The statistical properties of maximum likelihood estimators are derived, and a procedure to construct confidence intervals and do hypothesis testing is given. The relative merits of the linear and maximum likelihood estimators are analyzed. Other topics relevant to the identification and estimation methodologies, i.e., a continuous‐time solution to the flow equation, coping with noise‐corrupted head measurements, and extension of the developed theory to nonlinear cases are also discussed. A simulation study is used to evaluate the methods developed in

ISSN:0043-1397    

DOI:10.1029/WR023i001p00092

年代:1987

数据来源: WILEY