摘要:

A linear programing model is developed to select between modern surface and portable or semiportable sprinkler systems in two irrigation projects in Iran. Skilled labor is included in the model as one of the major limiting factors in the development of modern irrigated agriculture in a developing country.Under the specified conditions and assumptions, a portable or semiportable sprinkler system is indicated to be economically superior to a modern surface irrigation system for the development of new lands. However, in lands where a modern surface irrigation system has already been installed the transformation to sprinkler irrigation is not feasible. A completely automated sprinkler system is not indicated for either set of conditions in Iran. Primitive irrigation was not included in this study because of lack of data. Finally, the welfare effects of the choice of techniques are indicated.

ISSN:0043-1397    

DOI:10.1029/WR008i001p00001

年代:1972

数据来源: WILEY

摘要:

When estimating the benefits from a proposed irrigation project it is desirable to know the best area size to develop for irrigation in conjunction with a given dam. To determine this area realistically both stochastic demand for and stochastic supply of water should be taken into account. In turn, these factors involve the need to know the best area to plant as a function of beginning‐season reservoir levels and the best way to allocate a given quantity of water over an irrigation season. Incorporating the results of models that give solutions to these latter problems into a simulation model and applying it to a hypothetical situation produced estimates of the best acreage to develop for irrigation. The result is sensitive to changes in the fixed costs of the system, and the penalty arising from choosing suboptimal acreages is much greater than the likely costs of applying the model. Although this application of the model has limitations, the basic approach is capable of useful elaboratio

ISSN:0043-1397    

DOI:10.1029/WR008i001p00007

年代:1972

数据来源: WILEY

摘要:

A landowner in a floodplain must choose a way to use his land fromnavailable alternative activities. We develop a model that describes that choice as a function of the probability of a flood when the criterion is expected present value. We show the expected present value calculations for four simple benefit stream patterns: no‐decay, one‐hoss shay, experimental decay, and delayed benefits. Within this model we define and discuss several often elusive concepts: the damage due to one flood, the hazard due to being in the floodplain, and the benefits of flood probability reduction. We then show the relationship between the benefits of flood control and damage reduction, and point out that they are not identical. With this model we have a common framework for comparing such disparate flood relief and control policies as floodplain zoning and flood relief measures. Finally we show the misallocative effects of simple flood relief polic

ISSN:0043-1397    

DOI:10.1029/WR008i001p00018

年代:1972

数据来源: WILEY

摘要:

The role of Bayesian decision theory in hydrologic design problems is presented both in theory and by example. The theory is applied to an actual flood levee design problem on the Rillito Creek floodplain in Tucson, Arizona. Computer solutions provide a basis for judging the costs of overdesign in the face of uncertainty in the parameters of the flood frequency model (log normal) and for determining the worth of hydrologic data. One conclusion is that decision theoretic analysis looks at the decision situation from the standpoint of the engineer: how can one best decide in the face of limited data and the present knowledge about system behavior?

ISSN:0043-1397    

DOI:10.1029/WR008i001p00033

年代:1972

数据来源: WILEY

摘要:

Equilibrium temperatureTeis the water surface temperature at which net energy exchange to the atmosphere is zero. Since heat loss rate is a function of (Tw−Te), whereTwis the actual water surface temperature, the concept of equilibrium temperature is useful in predicting water temperatures. By selecting a set of equations to describe the heat exchange processes at the surface, one can produce curves of heat exchange rate (excluding shortwave radiation) versus (Tw−Ta), whereTais air temperature. These curves can be approximated by linear functions. The slopesqand interceptsQoof these curves are in turn linear functions of wind speed for a specified set of weather conditions (clear and low humidity or cloudy and high humidity). Specifying these weather conditions, wind speed, air temperature, and net incoming solar radiationQR, one can calculateqandQoand compute the equilibrium temperature asTe= [(QR−Qo)/q[ +Ta. This relation provides a simple yet general means of calculatingTeand can be used to investigate time variations ofTwin response to meteorologic condi

ISSN:0043-1397    

DOI:10.1029/WR008i001p00042

年代:1972

数据来源: WILEY

摘要:

The kinetics of many biologically and chemically reactive substances in natural waters can be approximated by first order reactions. A recurrence formula is presented that relates the concentrations in the sequence to the concentration distribution of the first reactant in the sequence. This recurrence relation applies to general spatial and temporal regimes. In particular, the recurrence relation immediately extends the known analytical solutions for a single first order reacting substance to any sequentially reacting set of substances for various spatial and temporal settings. This increase in the applicability of known solutions renders problems soluble that had heretofore been difficult to analyze.

ISSN:0043-1397    

DOI:10.1029/WR008i001p00050

年代:1972

数据来源: WILEY

摘要:

Studies on seven small watersheds have shown that monthly runoff can be satisfactorily predicted from a self‐calibrating four‐parameter model. The model requires as input the estimated average potential evapotranspiration and the daily rainfall. In addition at least one and preferably two or three years of observed monthly flows are required for parameter estimation. The model is adaptable to a wide range of hydrologic conditi

ISSN:0043-1397    

DOI:10.1029/WR008i001p00058

年代:1972

数据来源: WILEY

摘要:

A conceptual model was used to generate synthetic error‐free runoff data from precipitation and potential evaporation records. Random errors were then introduced into all three data records. By automatically and objectively fitting the model to different combinations of error‐free and error‐contaminated records, the effects of the errors on the fitting were studied. The value of the fitting criterion was found to depend largely on the errors in the runoff record. The variations in the final parameter values for fittings to error‐contaminated data were shown to be no greater than for the error‐free case. The data were then used to find the sensitivity figures for each parameter by a method that is less localized than the standard perturbation

ISSN:0043-1397    

DOI:10.1029/WR008i001p00070

年代:1972

数据来源: WILEY

摘要:

Hydrologists unfamiliar with computer programing methods can use Hymo to great advantage in watershed modeling. This problem‐oriented computer language provides twelve commands, commonly used in hydrology, to transform rainfall into runoff hydrographs and to route these hydrographs through streams and valleys or reservoirs. These functions make Hymo quite useful in the design and evaluation of flood control structures, flood forecasting, and research studies. The procedures used in Hymo were selected because of their accuracy, simplicity, and practicality. The input data required for Hymo are normally available for most watersheds. Hymo is quite flexible in that hydrologists familiar with Fortran 4 programing can easily add new commands or modify the present command

ISSN:0043-1397    

DOI:10.1029/WR008i001p00079

年代:1972

数据来源: WILEY

摘要:

Forecast models using historical time series data for temperature and flow are constructed by means of parametric time series models recently proposed by G. E. P. Box and G. Jenkins. An exposition of the new methods and two examples of data illustrative of the iterative procedures necessary to construct a good forecast model are given. The daily water temperature and Ohio River discharge at Wheeling, West Virginia, for January 1, 1963–December 31, 1968, provide the raw material for the models. The methods are easily extended to other problem

ISSN:0043-1397    

DOI:10.1029/WR008i001p00087

年代:1972

数据来源: WILEY