摘要:

A methodology for estimating direct recreational benefits from water pollution control was developed through a model of biological and behavioral relationships involved in sports angling. A biological production function was envisaged between inputs of angling effort and the output, or yield, of fish taken. The marginal product, angling success per unit of effort, was taken to represent the ‘quality’ of the recreational experience. Water pollution would cause deteriorations in dissolved oxygen, temperature, or toxicity characteristics of the water, thus shifting the production function downward and causing reductions in angling success, angling effort, and recreational value of the fishery. Demand equations and ‘success‐effort’ elasticities were estimated for three estuarial sports fisheries, and the methodology was illustrated by means of an assumed reduction in angling success. The direct recreational benefits were identified as the consumer surplus that would result from the prevention of water pollution. (Key words: Economics; quality of water; re

ISSN:0043-1397    

DOI:10.1029/WR002i002p00167

年代:1966

数据来源: WILEY

摘要:

A compulsory flood loss insurance scheme is one means of achieving efficient uses of flood plain lands. Insurance premiums proportional to risk and equal to both the private and the social cost of flood plain occupance will serve as a rationing device, eliminating economically unwarranted uses of flood plain lands on the one hand, while not prohibiting uses for which a flood plain location has merit on the other hand. In addition, reduction of flood loss insurance premiums can serve as a standard to measure the economic justification of alternative flood control measures and/or discrete increments in scale of protective works or other nonstructural flood control measures. A final advantage of flood loss insurance, which no alternative in flood management possesses, is indemnification for the residual damage potential against which it is not economic to seek protection. (Key words: Economics; flood control; flood plains; floods.)

ISSN:0043-1397    

DOI:10.1029/WR002i002p00183

年代:1966

数据来源: WILEY

摘要:

Expressions in terms of sample size and parameters of the probability distribution are obtained for the standard errors of sample estimates of flood magnitudes corresponding to given return periods for normal and double exponential universes. These errors are shown to converge toward fixed proportions of the estimates for very high return periods. (Key words: Floods; frequency analysis; statistics.)

ISSN:0043-1397    

DOI:10.1029/WR002i002p00191

年代:1966

数据来源: WILEY

摘要:

The law of stream orders can be deduced by assuming that river junctions are subject to a statistical branching process. (Key words: Drainage basin characteristics; river classification; statistics.)

ISSN:0043-1397    

DOI:10.1029/WR002i002p00199

年代:1966

数据来源: WILEY

摘要:

A detailed study of lake evaporation in Illinois has been made utilizing a technique developed by the United States Weather Bureau. Monthly lake evaporation and pan evaporation have been computed for a 52‐year period utilizing parameters of air temperature, dewpoint, solar radiation, and wind movement. Records of seven weather stations in and around Illinois were used. The results were checked against observed pan evaporation data for various periods of years available at seven locations. The resulting map of annual lake evaporation in Illinois is based on considerably more information than was previously available and permits more efficient design and operation of water supply impoundments. (Key words: Computers, digital; evaporation; lakes; reservoirs; water management

ISSN:0043-1397    

DOI:10.1029/WR002i002p00205

年代:1966

数据来源: WILEY

摘要:

A graphical recorder for a pan evaporimeter has been developed. Water from a reservoir is pumped at a steady rate to the pan in which an overflow device maintains constant level, the overflow water being returned to the reservoir by gravity flow. The change in level of the water in the reservoir represents the difference between evaporation from the pan and precipitation. The record is made on a vertical cylindrical chart, the recording pen having direct coupling to a float in the reservoir. Recording amplification is determined by the pan‐to‐reservoir area ratio. In the present model, amplification values of 2 and 5 can be selected by a cock that controls a tubular by‐pass between concentric reservoirs. (Key words: Evaporation; instrum

ISSN:0043-1397    

DOI:10.1029/WR002i002p00209

年代:1966

数据来源: WILEY

摘要:

Tallow alcohol (TA) affects the properties of water in soil by forming compressed monolayer films on the water‐filled pores of the soil. Besides directly effecting a small evaporation reduction, the films lower the soil‐water tension. This tension‐lowering leads to several other effects, including reduction of the flow rate of water through uniform soils and, in layered soils, lowering of the soil‐water concentration in the TA‐containing layer. The last effect, which leads to self‐mulching, accounts for most of the substantial evaporation reduction from soils with TA in the surface layer. This effect also aids the infiltration of water into such soils. The full effects of TA are realized only when it is solvent‐dispersed; with powdered TA only partial effects are obtained. Attention is directed to the possible effects on the soil‐fatty alcohol‐water system of soil micro‐organisms growing on fatty alcohol. (Key words: Evaporation; infiltration; so

ISSN:0043-1397    

DOI:10.1029/WR002i002p00213

年代:1966

数据来源: WILEY

摘要:

The heat balance of a U.S. Weather Bureau class A evaporation pan located near Tucson, Arizona, was calculated for selected periods during the interval July 26–31, 1963. The method used required two pans, one of which was insulated on the side and bottom to prohibit heat transfer through these surfaces. For 10 of the 14 observation periods, heat transferred into the uninsulated pan via the side or bottom accounted for 29% of the total heat added to the pan. In the remaining periods, 6% of the heat leaving the pan was transferred through the side or bottom. Elimination of this heat transfer in the insulated pan resulted in an average daytime water temperature 2°C lower than that in the standard pan and a reduction of the daily evaporation rate by 28%. The data show the necessity of taking into account the heat transfer through the walls of the pan, especially when evaporation of natural water bodies is estimated from pan evaporation data. The heat balance method described offers one way in which the magnitude of this heat transfer can be determined. (Key words: Evaporation; lakes; meteorology; hydrolog

ISSN:0043-1397    

DOI:10.1029/WR002i002p00223

年代:1966

数据来源: WILEY

摘要:

The transient values of water pressure, water content, and rate of water evaporation from soils can be predicted theoretically from the mathematical model representing the physical problem of the evaporation phenomenon from soils. Evaporation of water from a soil surface is an initial‐value problem arising in many cases of water transfer through soils. A nonsteady state exists that leads to the mathematical model of a nonlinear parabolic partial differential equation in which the time and the position in the vertical direction are taken as the independent variables and the volumetric water content as the dependent variable. Because of the strong nonlinearity, the governing partial differential equation is approximated by finite differences at discrete mesh points in the solution domain and is integrated for initial and boundary conditions corresponding to the evaporation phenomenon. The procedure for the numerous calculations required for the numerical integration is programmed in Fortran coding language, and fast answers consisting of transient values for the pressure distribution, water content, and evaporation rate are obtained with the aid of an electronic digital computer IBM 704. (Key words: Evaporation; porous mediums; soil moisture; unsaturated flow

ISSN:0043-1397    

DOI:10.1029/WR002i002p00227

年代:1966

数据来源: WILEY

摘要:

Moisture movement to a freezing front in an unsaturated porous medium of Fairbanks silt was measured by γ‐ray attenuation. It was shown that the presence of an ice phase greatly enhances the amount of moisture transfer under temperature gradients. The chemical potential of soil water in the frozen soil as a function of temperature is calculated. The chemical potential of unfrozen absorbed water in frozen soils, if in equilibrium with ice, is independent of total water content (unfrozen water plus ice). Consequently, no equilibrium moisture content distribution is reached, and water content in the frozen soil changes continuously. Moisture flow in the frozen soil takes place under temperature gradients through the films of unfrozen water. Since the thickness of the unfrozen films decreases with temperature, the rate of water transport also decreases rapidly with decreasing temperature below 0°C. (Key words: Frost; soil moistu

ISSN:0043-1397    

DOI:10.1029/WR002i002p00241

年代:1966

数据来源: WILEY