摘要:

Four variables involved in the water resources planning decision characterized by hydrology, modeling of dissolved oxygen behavior in an estuary, projection of economic development, and water quality objective, were tested for sensitivity in the evaluation of a water resources system's performance. The results were obtained assuming a 25% range in economic projection, 1 mg/1 range in the dissolved oxygen objective, two separately developed models of estuarial dissolved oxygen behavior, and 50‐ and 10‐year sequences of hydrologic data. The results of simulations of system operation with the different values of the planning variables were subjected to a four‐way analysis of variance to partition the variance attributable to each planning variable. For the system under consideration, the relative importance of the variables in descending order is: (1) economic development projection, (2) water quality objective, (3) dissolved oxygen modeling, and (4) hydr

ISSN:0043-1397    

DOI:10.1029/WR005i006p01165

年代:1969

数据来源: WILEY

摘要:

Investment programing for multiple objectives rather than simply for the traditional water resource investment objective of increasing the national income has become an important new element in water resources planning in the United States. Reference is made to current multiple objective planning efforts, and the relevant theory is briefly explained. The benefit‐cost ratio appropriate to projects in multiple objective programs is presented, and it is shown how this ratio differs from the ratios required by current federal instructions, which do not allow agencies to reflect accurately the interaction of social preferences and investment opportunities. A change in the federal instructions is recommende

ISSN:0043-1397    

DOI:10.1029/WR005i006p01174

年代:1969

数据来源: WILEY

摘要:

This paper discusses the problems involved in identifying valid demand and supply parameters estimated from sample data on recreation. It is argued that an analysis of cross section data permits the quantification of the effects of demand variables. Cross section results can then be pooled with recreation time series to enable the valid estimation of supply parameters. These supply parameters can be used to improve decisions regarding the expansion and development of recreation sites. More refined projections of rates of use can be derived for use as benefit measures in cost‐benefit analysis. An example of the pooling technique is presented using demand equations estimated from the National Recreation Surveys and a time series of visitation data at the Tennessee Valley lakes. The results tend to confirm the superiority of the method proposed, particularly in comparison with an analysis using only time series dat

ISSN:0043-1397    

DOI:10.1029/WR005i006p01179

年代:1969

数据来源: WILEY

摘要:

The marginal value of water for dilution of waste is observed to be small when computed on either a long run or a short run basis. A policy of clean water places a low marginal value on dilution water since these values increase in many situations with any increase in allowable concentration of waste in the receiving water. The marginal value of waters used to dilute saline irrigation return flows is generally higher than those used to dilute oxygen demanding wastes because of the relative currently higher salt removal treatment costs and the much higher allowable receiving water concentration for most salts.

ISSN:0043-1397    

DOI:10.1029/WR005i006p01186

年代:1969

数据来源: WILEY

摘要:

A minimum present cost strategy for investment in water projects is derived. An increase in demand for water is considered to be supplied by a number of projects that have an indefinite life. The optimum sequence of installation of these projects is determined by (1) the shape of the water demand/time relationship, (2) the appropriate interest rate, and (3) the relative costs and capacities of the facilities from which a selection is made. A general method to derive the optimum sequence of construction is developed using dynamic programing. Examples of the use of the technique are given.

ISSN:0043-1397    

DOI:10.1029/WR005i006p01196

年代:1969

数据来源: WILEY

摘要:

The purpose of this study is to define ‘critical period’ in conjunction with reservoir design and operation and then to analyze the usefulness of the concept in the evaluation of deficiencies of water for project planning purposes. Streamflow records from a number of rivers in the United States are analyzed, and certain defined characteristics of their various critical periods are derived. These characteristics are shown to be functions of both the active storage and the degree of variation in annual streamflow. The dates of occurrence of the critical periods from historical records tend to be stable within certain geographic areas and over a range of active storages. A study is made of the significance of the critical periods and their associated droughts respecting their use for design purposes. This is done by generating large numbers of equally likely hydrographs of the same length as the historical record and comparing the critical periods and yields of these synthetic records with those found in the historical record. Some of the synthetic records produced critical periods in which the severity, measured by the decrease in the full record firm yield, was greater than the historical. However, the generated records as a whole had significantly less severity than the historical records of the same length. The critical periods also showed a strong tendency for nesting, i.e., the larger critical period includes within its duration the smaller critical periods over a wide range of storage and target draft. These observations suggest, but do not prove, that the more severe critical periods observed in historical records may be due to major perturbations of the cause‐effect relationships not reflected by the hypothesis of static probability relationship (i.e., constant parame

ISSN:0043-1397    

DOI:10.1029/WR005i006p01205

年代:1969

数据来源: WILEY

摘要:

In justifying small watershed projects under Public Law 566, the U.S. Soil Conservation Service (SCS) frequently counts as a benefit the intensified use of agricultural land resulting from increased flood protection. This paper, based on a study of a watershed project in southwestern Wisconsin, shows that actual land use changes were far less than predicted by the SCS. The reasons are less related to the watershed project than they are to changes in farming practices. Questions could be raised concerning the adequacy of project evaluation techniques.

ISSN:0043-1397    

DOI:10.1029/WR005i006p01216

年代:1969

数据来源: WILEY

摘要:

A technique for selecting flood protection levels that exceed mean flood intensities by a large amount is based on a probability model derived from the assumption that base flow floods occur at random with exponentially distributed magnitudes. It is a parametric approach involving the estimation of two statistical parameters by the method of maximum likelihood. The sensitivity of the results to errors made in choosing the correct flood intensity distribution is examined by computing the loss when the flood intensities are log normally distributed. This loss is shown to be small over a wide range of parameter values likely to be encountered. Through the use of a quadratic loss function it is shown that the expected loss is inversely proportional to the length of record. Furthermore if the existing level of protection exceeds the mean peak flood intensity by a large amount, then parameter estimation losses can be quite large, even when a record of considerable length is available. The quadratic loss function also demonstrates that the loss is due primarily to errors in estimating the expected flood intensity.

ISSN:0043-1397    

DOI:10.1029/WR005i006p01223

年代:1969

数据来源: WILEY

摘要:

An exponential relation was developed to describe the spatial distribution of convective storm rainfall in southwestern United States. Given that a storm center has occurred, a geometric distribution was used to describe the frequencies of point rainfall depths. A Poisson distribution was assumed to represent the probability of at least one storm center occurring over a given area a specified number of times during a season. Assuming that the two probability distributions are independent and uncorrelated, maximal and minimal distributions of point rainfall depths were derived. The minimal distribution indicates that with a very high certainty a single rain gage will miss at least one convective storm a year. When compared with frequencies determined from long‐term historical records, the maximal distribution exhibits a similar mean, a greater variance, and lower recurrence intervals for the higher rainfall depth

ISSN:0043-1397    

DOI:10.1029/WR005i006p01229

年代:1969

数据来源: WILEY

摘要:

Estimation of the parameters of Gumbel's third asymptotic distribution of the smallest value has been accomplished in the past by the following methods: (1) the method of moments; (2) using an order statistic on the characteristic drought; and (3) using the smallest observed drought. These three methods are compared with a fourth method that uses sequential least squares and a Fibonacci search. Based on estimates of the parameters of 44 rivers in the United States, it appears that methods 1, 2, and 3 do not give a satisfactory estimate of the smallest drought in a large number of cases. The method of using an order statistic was the least successful. The use of the least squares and Fibonacci search approach gave more acceptable estimates than the other methods.

ISSN:0043-1397    

DOI:10.1029/WR005i006p01238

年代:1969

数据来源: WILEY