摘要:

ABSTRACTThe Las Vegas, Nevada area like most semi‐arid basins, was developed through exploitation of available ground‐water resources. Area growth in this large valley has occurred in a scattered and sporadic manner with development both in incorporated areas and within the County. As a result, today there exist five major water suppliers which are: a water district, three municipalities, and a large corporation, in addition to numerous small water companies and thousands of domestic wells. In the past 20 years the area has grown from a population of less than 50,000 to over 300,000 today. The bulk of the water demand for this growth has been met from the ground‐water resource and as a result the basin is being severely mined. Current extractions are over three times the estimated annual replenishment. Rapidly declining water levels are increasing the costs of water and are creating water shortages during periods of peak demand. To meet both the current and anticipated water demands, the Southern Nevada Water Supply Project is being constructed to import additional water from nearby Lake Mead.Agriculture in the area is very limited, and primarily uses reclaimed waste water for irrigation. The chief water demands in the area are thus municipal and industrial, with the former predominating.This study was designed to determine how best the Las Vegas Valley Water District, supplier of 80 percent of the domestic water, might integrate the use of the existing ground water and anticipated imported surface water. Additionally the consequences of application of certain provisions in the Nevada Water Law were examined to determine their effects on the ground‐water system and costs of water.To achieve these objectives, a dynamic programming technique was utilized. The problem as formulated consists of a single decision variable, single state variable dynamic programming algorithm evaluated over a fifty‐year planning horizon at monthly intervals. Three alternative solutions, with different ground‐water law constraints are evaluated.In all solutions certain basic operating rules regarding ground‐water pumping distribution and use of surface‐water systems are kept constant.The problem is considered as deterministic in all respects. Recharge to ground water is assumed to equal the estimated average annual replenishment evenly distributed over the year and additionally is not considered to be a function of average basin ground water potential. The only surface supply, Lake Mead, is considered to operate at near constant elevation and not be subject to shortage conditions. In light of the size of Lake Mead, the Colorado River flow and the size of Nevada's allotment, 300,000 ac ft, the latter assumption is reasonable. Demand for water is considered as a known function of time.Optimization of conjunctive use for the Water District is based on the objective function of minimizing water production costs. Costs of distributing water are considered to be constant regardless of source, and so are not included. Also, fixed costs of amortizing the pipeline project and well fields are not considered.Results of the study are presented as a series of policy traces under each of the three alternatives considered. These traces describe the ground‐water basin response under optimal operating conditions, given an estimate as to the present worth of ground‐water pumping rights, and prescribe monthly water‐procurement schedules for the operation

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00484.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTThe environmental pollution problems prevalent in gulf coast estuaries are a cause of great concern to those in water quality management. This paper outlines the dominant characteristics which affect the properties of these estuaries including geography, tide and current effects, wind effects, salinity and density regime, nature and level of waste discharge, low inflow levels, dredging effects and present quality levels.Two basic levels of analytical modeling which are useful in water quality management are presented. The first is a relatively crude completely mixed estuarine model which permits economical evaluation of varying parameters. The second is a very general steady state model which permits analysis of stratified systems. The ESTPOL computer language designed to simplify the use of the steady state model is described.The practical use of the analytical models as management tools for the solution of Texas Estuarine quality problems is demonstrated.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00485.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTA very fashionable term in present day engineering is mathematical model. A term which has grown into somewhat ill‐repute is “curve fit.” The basic purpose of this paper is to discuss the difference between a mathematical model and a “curve fit.” In addition, a discussion of proof testing of both “curve fits” and mathematical models will be presented, followed by a brief discussion of the form and of the uses of “curve fits” and ma

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00486.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTRegulated water flow is an essential feature of modern civilization. Effective use of water resources by industrial, agricultural, and municipal processes, as well as domestic conveniences, require controlled flow systems. Closely related to this regulation is the requirement for flow measurement, the techniques of which have developed over many centuries. Because of the relatively long history of flow metering and the multitude of improvements and new developments, a complete coverage of the subject is beyond the scope of this paper. Greater emphasis is placed on describing new developments and less conventional methods that are most usable for water resource applications and research studies, and less emphasis on older, generally familiar devices. Because of the diverse requirements in water measurement, few devices can be regarded as having no possible application. The selection of the most usable devices is somewhat arbitrary. Thus, at least passing mention will be made of most known devices for all fluids, and the reader guided to reference material for more complete coverage of a particular device or system.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00487.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTComputer simulation of river basin hydrology has rapidly progressed from an interesting academic exercise to a practical engineering procedure of increasing utility. Mathematical models of the many interrelated processes which occur in a basin have been developed along with efficient numerical procedures for their solution. The present paper is concerned with a particular model which has been used to describe the transformation of a temporally and spatially varying rainfall into a time history of stage and discharge on a flood plain. Although developed principally as a model of the physical processes involved, it is envisioned that the model can serve as one component of an information system for flood plain planning and management.The model consists of the following elements: (i) a rainfall simulation which generates stochastic inputs to the model according to specified rainfall statistics, (ii) a catchment‐runoff model which converts the rainfall to surface runoff, (iii) a flood stage model which converts the surface runoff to time histories of flood stage and discharge.The model has been used to investigate the effect of various structural flood control measures in a basin and, in particular, to establish frequency‐stage information for each of these.Of particular interest in development of the model have been recurring and partially unanswered questions relative to the proper balance among availability of data for use in the model, data requirements of the model and the objectives of the outputs produced by the mo

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00488.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTWithin the past few years, a number of papers have been published in which stochastic mathematical programming models, incorporating first order Markov chains, have been used to derive alternative sequential operating policies for a multiple purpose reservoir. This paper attempts to review and compare three such mathematical modeling and solution techniques, namely dynamic programming, policy iteration, and linear programming. It is assumed that the flows into the reservoir are serially correlated stochastic quantities. The design parameters are assumed fixed, i.e., the reservoir capacity and the storage and release targets, if any, are predetermined. The models are discrete since the continuous variables of time, volume, and flow are approximated by discrete units. The problem is to derive an optimal operating policy. Such a policy defines the reservoir release as a function of the current storage volume and inflow. The form of the solution and some of the advantages, limitations and computational efficiencies of each of the models and their algorithms are compared using a simplified numerical example.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00489.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTTo the average layman, the distinction between opinion and attitude is artificial at best, and is neither consistent nor logically defensible. For many purposes one need not distinguish between the two. However, when assessing opinion and attitude the disparity becomes quite evident. Opinion surveys are characteristically concerned with replies to specific questions which need not be related. The responses are kept separately as opposed to being combined into a total score. Attitude scales, on the other hand, typically yield a total score indicating both a direction and intensity of an individual's feelings, thoughts, and predispositions to act toward a given concept. Further, in the construction of an attitude scale, the different statements are designed to measure a single attitude or unidimensional variable. The Likert method of constructing attitude measuring instruments requires a large number of judges to indicate their own attitudes by responding to statements thought to pertain to an attitude in question. Five possible responses are provided for each item. The procedure for construction of a Thurstone type scale utilizes the Law of Categorical Judgment as a basis. Statements are obtained and analyzed for the various categories and in final form, the attitude scale is presented to the respondent who indicates statements with which he agrees or disagrees.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00490.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTA statistical technique which offers considerable promise in ground water studies is the fitting of polynomial trend‐surfaces to ground water data and studying the variations in the surfaces and the residuals from these surfaces over a period of time.The application of trend‐surface analysis to ground water study is based on the premise that the piezometric surface or water table can be approximated by a mathematically computed polynomial surface of the water levels of the wells in the aquifer.The evaluation of trend surface analysis application in ground water investigations was made up essentially of two considerations; a study of the relationship existing between the trend surfaces and the actual ground water surface and a study of the potential use of the residuals from the trend‐surfaces to assist in the location of favorable sites for future development of ground water resources. The conclusions on aquifer behavior drawn from the trend surface analysis were compared with conclusions drawn from a concurrent survey of ground water conditions carried out independently of this investigation. This comparison provided the basis for the critical examination of the application of trend‐surface analysis in ground water investi

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00491.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTThe basic theories and fundamental assumptions usually employed in the solution of unsteady groundwater flow problems are reviewed critically. The best known method of analysis for such problems is based on the Dupuit‐Forchheimer approximation and leads to a nonlinear parabolic differential equation which is generally solved by linearization or numerical methods. The accuracy of the solution to this equation can be improved by use of a different approach which does not employ the Dupuit Forchheimer assumption, but rather is based on a semi‐numerical solution of the Laplace equation for quasi‐steady conditions. The actual unsteady process is replaced by a sequence of steady‐state conditions, and it is assumed that the actual unsteady flow characteristics during a short time interval can be approximated by those associated with “average” steady state flow. The Laplace equation is solved by a semi‐discretization method according to which the horizontal coordinate is divided into subintervals, while the vertical coordinate is maintained continuous. The proposed method is applied to a typical tile drainage problem, and, based on a comparison of calculated results with experimental data, the method is evaluated and practical conclusions regarding its applicability

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00492.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

ABSTRACTTo aid in planning and design of additional flood protection on the Lower Rio Grande, the Hydroraeteorological Branch prepared a probable maximum precipitation study for the International Boundary and Water Commission (United States and Mexico) and the Republic of Mexico. Five drainages from 2,000 to over 17,000 square miles in area between Falcon and Anzalduas Dams including Rio San Juan and Rio Alamo in Mexico are the areas of concern. The great rains of hurricane Beulah, September 19–24, 1967 verified that additional protection is needed. Procedures for estimating probable maximum precipitation (PMP) are described. A particular problem was to estimate rainfall potential for the Sierra Madre Oriental in Rio San Juan and Alamo drainages. These mountains form a north‐south windward‐facing slope and barrier of over 7000 feet in elevation. A detailed study was made of rains from hurricane Beulah. The storm produced the greatest known rain depths in North America for 50,000 square miles or greater, and durations longer than 48

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1970.tb00493.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY