Water Resources Research

Minhas, B. S.; Parikh, K. S.; Srinivasan, T. N.

doi: 10.1029/WR010i003p00383pmid: N/A

The interdependence between the rate of water used by plants and the available stocks of moisture in the soil, the temporal interdependence between water use at different time points, and the consequences of these interdependencies for the relationship between time profiles as well as the quantities of water used by crop plants and yields have not generally been analyzed in a unified framework. We present one such unified framework for the analysis of optimal use of irrigation water. We have estimated from experimental data the mathematical form of a water use function and have used this function to compute the time profiles of actual water use for two crops: wheat in Delhi and alfalfa in Ohio. The estimated time profiles of consumptive use have been used to determine the relationship between wheat yields and dated inputs of water in Delhi.

Hamill, Louis

doi: 10.1029/WR010i003p00395pmid: N/A

Leopold has published a set of techniques for comparing aesthetic factors among rivers, which include uniqueness ratios and graphic derivations of scale of river character and scale of valley character. The usual practice in evaluating recreational and scenic resources is to use a consistent rating scheme and to derive summary measures of attractiveness by adding evaluation numbers or ratings. The latter procedures were used to test Leopold's methods by using the Spearman rank correlation coefficient to compare rankings by the two methods. There was poor correlation between evaluation numbers and uniqueness ratios for physical and water quality factors. Correlation was better for human use and scenic factors. The meaning of additive evaluation numbers is more comprehensible than the meaning of additive uniqueness ratios; the additive uniqueness ratios were concluded to be less efficient. The graphic procedures were found to introduce unexpected anomalies in combining two or more sets of factors, and the addition of evaluation numbers was concluded to be more reliable. The addition of evaluation numbers requires less time and effort than the procedures advocated by Leopold and is less subject to errors.

De Rooy, Jacob

doi: 10.1029/WR010i003p00403pmid: N/A

In order to determine the sensitivity of the industrial demand for water to changes in price a simple set of demand equations is formulated and tested with data on water use by 30 large plants. Results suggest that firms do adjust quantities demanded in response to even small price changes. Demand is also significantly affected by changes in output, by technological improvements, and by employment.

Takeuchi, Kuniyoshi; Moreau, David H.

doi: 10.1029/WR010i003p00407pmid: N/A

A method for finding optimal operating policies for a multiunit water resource system that extends over two river basins and serves multiple demands is presented. The method was developed and tested for one of several systems that have been proposed for further development of the water resource in the urbanizing Piedmont Triad region of North Carolina. Monthly operating decisions are given by solutions of a piecewise linear programing problem, the objective function for which consists of two parts, immediate economic losses within the month and the expected present value of future losses as a function of end‐of‐month storage levels in the reservoirs. The latter function is estimated by imbedding the linear programing problem in a stochastic dynamic programing problem. An approximate solution technique for the larger problem is described, and computational experience is reported.

Porter, Richard C.

doi: 10.1029/WR010i003p00415pmid: N/A

Primers on the discharge of unwanted but unpriced effluents into the air and water now treat as a commonplace the symmetry between taxes (or charges) on effluents and subsidies (or bribes) for abatement as means of reducing an industry's pollution. This note shows that, on the contrary, serious asymmetry results when entry and exit occur in response to subsidies or taxes. Not only does the quantitative symmetry disappear, but even the qualitative impact (i.e., the directions of the effects) of charges and bribes on the volume of firm and industry effluents may differ. More specifically, the possibility emerges that an abatement subsidy offered to an industry may increase the total effluents of that industry.

Smith, R. E.; Schreiber, H. A.

doi: 10.1029/WR010i003p00418pmid: N/A

As a sequel to an earlier study of the stochastic properties of daily rainfall occurrence in a summer thunderstorm season, the probabilistic nature of daily rainfall depths is examined. Daily rainfall depths are found to be well described by what may be termed a compound exponential distribution. Some 1600 to over 2000 daily rainfalls from three stations are partitioned in various conceptual ways to evaluate homogeneity with respect to the pattern of occurrence with sequences or seasons as well as the annual variance of population properties. Although some small but statistically significant inhomogeneities are found, the statistical description of depths in arbitrary intervals, such as annual total depths, is shown to be treatable as the sum of a random number of (independent) random variables by using the model for rainy day occurrence. Simulations from this model match well the measured data from the stations treated. The effect of truncation of the rainfall sample on both depth distribution and Markov chain dependence is discussed. It is also indicated how daily depths are functions, in turn, of individual storm occurrence probability (number per day) and storm depth distributions.

Smith, Roger E.

doi: 10.1029/WR010i003p00424pmid: N/A

Following a two‐part study of the stochastic nature of thunderstorm occurrence and the probability of daily rainfall depths, the importance of point rainfall information to areal rain distribution is indicated. A probabilistic expression is developed for the relationship between the point depth of rainfall, the local probability distribution of storm cell maximum depth, and the dimensionless expression of storm depth area pattern. In a sample test the expression is successfully used to reproduce point rainfall depth probability from storm maximum depth distribution and depth area data from Tombstone, Arizona.

Moss, M. E.; Karlinger, M. R.

doi: 10.1029/WR010i003p00427pmid: N/A

The statistical characteristics of the accuracy of regression analyses as used in surface water regionalization are investigated by simulating logarithmic regressions of the streamflow parameters, mean and standard deviation, derived from synthetic streamflow sequences. Accuracy is measured in terms of equivalent years of at site record. A procedure for the design of surface water data networks that accounts for the statistical nature of the estimates of parameter accuracy is presented.

McPherson, Murray B.; Schneider, William J.

doi: 10.1029/WR010i003p00434pmid: N/A

Modeling of urban watersheds is complicated by the complexities of the hydrologic system brought about by urbanization, model scale, and client diffusion. Modeling objectives vary widely, from storm sewer design to management of local runoff to river basin planning. Each objective requires a different approach to modeling. Current difficulties in modeling involve inherent nonlinearities in most methods of processing inputs for linear models, problems of storm definition, interconnection of urban catchment areas, and shortage of detailed rainfall‐runoff water quality data for calibration. Despite handicaps, progress has been made in modeling urban watersheds and will continue to be made.

Brater, E. F.; Sangal, S.; Sherrill, J. D.

doi: 10.1029/WR010i003p00441pmid: N/A

The effect of urbanization on flood flows is being investigated by analyzing inputs and corresponding flood hydrographs from many watersheds along with corresponding inputs and responses from watershed models. The inputs consist of precipitation plus snowmelt minus infiltration and retention. Because of the large seasonal variation in infiltration rates, accuracy was improved by treating rainfall frequencies seasonally in predicting flood runoff from precipitation and snowmelt. As procedures were developed and improved in accuracy, it became necessary to examine the effect of snowmelt on winter frequencies and the seasonal variation in time‐intensity rainfall patterns more closely. A procedure was developed for including snowmelt with winter rains, and the resulting frequency curves of rain plus snowmelt are presented and compared with conventional rainfall frequency curves. A method of deriving time‐intensity patterns from daily rainfall was developed, and it was shown that a large difference exists between typical winter and summer patterns in southeastern Michigan.