bluuebunny/crossref_metadata_2025 huggingface dataset:
An economic approach to coping with flood damage
Authors: Krutilla John V.
Published: February 2008

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.)
Fluid flow from nuclear chimneys
Authors: Korver John A.
Published: February 2008

One promising application of engineering uses for nuclear explosives is the creation of large underground rubble chimneys into which liquid wastes can be injected. To assess the feasibility of this application, a predictive capability has been developed by matching laboratory model studies with mathematical analogs. The effects of varying permeability, porosity, input flow rates, and chimney dimensions were examined. Variation between laboratory and mathematical model results was less than 10%. This paper describes the laboratory model studies of two hydrologic environments, the development of the mathematical models, and the numerical solutions obtained with the mathematical models. Also summarized are two examples of potential applications of nuclear explosives to the field of waste disposal. The results indicate that, for many selected hydrologic conditions, it is feasible to use nuclear rubble chimneys in permeable but unsaturated formations for the disposal of liquid wastes. (Key words: Nuclear explosives; waste disposal; groundwater.)
Storage requirements for water in the United States
Authors: Löf George O. G. , Hardison Clayton H.
Published: February 2008

Storage requirements for various levels of streamflow regulation in the 22 major regions of the contiguous United States are presented to supersede those given in Committee Print 32 of the Select Committee on National Water Resources, U. S. Senate. At high levels of development, the storage required to provide the desired flow in 95 and 98% of the years is substantially larger than that previously given. Carry‐over storage requirements based on probability routing of annual discharge are combined with seasonal storage requirements to give the revised storage requirements, which are then used to compute revised evaporation losses and revised cost estimates by the methods previously used. The maximum net flow that could be made available for the 22 regions for 98% of the years is shown to be 965 billion gallons per day (bgd) for which a storage capacity of 3.6 billion acre‐feet would be required. A net flow of 922 bgd could be made available with 2 billion acre‐feet of storage. Any increment of flow above the 922 bgd figure would have storage costs exceeding 10 cents per thousand gallons delivered.
The human factor and changes in water usage patterns
Authors: Bylund H. Bruce
Published: February 2008

There are certain trends in contemporary society that are generally accepted as facts. These trends include increasing population, increasing urbanization, and increasing industrialization. With these changes come increasing demands for water. Changes that allow for more efficient use of existing water supplies are inevitable.
The modeling of overland flow
Authors: Grace R. A. , Eagleson P. S.
Published: February 2008

The partial differential momentum and continuity equations governing two‐dimensional overland flow on a plane surface with vertical inflow are developed and normalized.Using extensive data from the literature on such subjects as rainfall, topographic characteristics, and unsteady overland flow, the individual terms in these normalized equations are compared on an order‐of‐magnitude basis. This comparison results in a systematic and justifiable simplification in the equations and thus in the similarity criteria given by heir coefficients. The criteria obtained are realizable over a limited, but significant, range of prototype rainfalls and land forms.
Retention of 65Zn by Columbia River sediment
Authors: Johnson Vernon , Cutshall Norman , Osterberg Charles
Published: February 2008

Less 65Zn is displaced from Columbia River sediments by the interaction of sea water than can be removed by leaching with solutions of certain first transition series metals. We interpret this to mean that ion exchange is not an important mechanism in the retention of 65Zn in these samples. Instead, much of the 65Zn is held by ‘specific sorption.’ Neither treatment displaced 51Cr or 46Sc from the sediments, whereas about one‐third of the 54Mn was removed upon contact with sea water.
Rainfall intensity and elevation in southwestern Idaho
Authors: Cooper Charles F.
Published: February 2008

There is no apparent relationship between elevation and the intensity of spring and summer rainfall in a 93‐square‐mile area with a range of 3500 feet in elevation in semiarid southwestern Idaho. Analysis covered four years' data from recording rain gages with an average density of 1 per square mile. Rainfall bursts amounting to 0.10 inch or more were considered. The maximum intensity recorded was 0.49 inch falling at 9.8 inches per hour. Rainfall in excess of 0.8 inch per hour occurred an average of once a year. The logarithm of the amount of rain falling in excess of a given intensity plots as a straight line against intensity. There is no difference in this relationship when the data are separated by elevation classes. The amount of rainfall decreases by about one‐half with each 1‐inch‐per‐hour increase in rainfall rate. This ratio may be a characteristic of the regional climate. It is suggested that data from accessible valley stations can be used to estimate the relative frequency of high intensity rains throughout an area of appreciable range in elevation.
Water in west Pakistan
Authors: Birkhead Guthrie S.
Published: February 2008

This article describes several of the salient problems about water and the administration of water programs in West Pakistan. The separation of India and Pakistan in 1947 divided the Indus Basin, leaving three major tributaries in India and most of the irrigated lands in Pakistan. The 1960 Indus Waters Treaty provides for a series of waterworks, financed primarily by Western countries, that will reroute much of the surface water in the Basin. Part of the water allotted to India will be replaced, and hopefully there will be a more dependable water supply for the 20 million acres of land in the Province's agricultural base. There and elsewhere severe waterlogging and salinity conditions have been growing rapidly, and other water problems abound. Since 1958 a semi‐autonomous government corporation has managed these water programs, as well as generating and wholesaling most of the electric power. The corporation currently spends well over a quarter of the total provincial budget for economic development purposes. Allowing such an agency to play so predominant a role is of course a matter of conscious policy choice. It may be argued that thus far this Pakistan corporation has performed constructively in the field of water and power, resource administration. (Key words: Agriculture; economics; planning; water management; water resources)
The persistence of silvex in water and hydrosoil
Authors: Cochrane D. R. , Pope J. D. , Nicholson H. P. , Bailey G. W.
Published: February 2008

The propylene glycol butyl ether ester of silvex, an herbicide useful to control aquatic plants, hydrolyzed almost totally to silvex acid in about two weeks when applied at the rate of 8 Ibs/acre (acid equivalent) to water overlying Cecil sandy clay loam, Lakeland loamy fine sand, and Brighton muck soils in plastic pools. Silvex acid increased in concentration in water for a week and then dissipated gradually over a 19‐week period. Apparent adsorption of both the ester and acid occurred on the hydrosoil and was followed by gradual diminution of both. Laboratory studies confirm that silvex acid can be adsorbed by the three soils. The possibility exists that silvex acid and/or a degradation product may be desorbed and readmitted to water. (Key words: Pollution; aquatic plants; soil )
Meteorological studies in the Marmot Creek Watershed, Alberta, Canada, in August 1965
Authors: Munn R. E. , Storr D.
Published: February 2008

The meteorology of a mountainous watershed in the Alberta Rockies is shown to be strongly influenced by upslope‐downslope diurnal wind circulations during rain‐free periods of observation in August, 1965. The evapotranspiration from the forest is inferred from measurements of net radiation above the canopy and from vertical temperature gradients obtained from an 80‐ft tower. The forest water loss during August rain‐free periods is estimated to be between 0.15 and 0.6 gm/cm2/day with high confidence, or between 0.25 and 0.48 gm/cm2 with somewhat less confidence. A ‘best’ engineering estimate of evapotranspiration is 0.3 gm/cm2/day.
Hydrology of surface mining—A case study
Authors: Stenberg Yaron M. , Agnew Allen F.
Published: February 2008

A mathematical model representing a strip‐mined area is formulated and analyzed. Solutions are obtained for the changes in ground water elevation and ground water flow that would occur in response to a uniform rate of deep percolation over the spoil bank. The solutions developed are for a bounded one‐dimensional aquifer (spoil bank) where the water level in the last cut (ditch) is a function of time described by an error function. Computed curves showing the ground water elevation for two particular sets of aquifer characteristics for various times are presented. The solution for the ground water flow can be used to forecast maximum and minimum flows from the spoil bank to the last cut. The formulation of the model is based on some preliminary data and may require some modification as more data become available.
Some thermodynamic relationships for soils at or below the freezing point: 1. Freezing point depression and heat capacity
Authors: Low Philip F. , Anderson Duwayne M. , Hoekstra Pieter
Published: February 2008

An extended equation was derived relating the relative partial molar free energy of water in a soil to its freezing point depression and relative partial molar heat content. The equation was used to prepare a table from which each of these three quantities can be ascertained if the other two are known. The table was used with experimental data to obtain a curve of freezing point depression versus water content for Na‐Wyoming bentonite. Provided the activity of the liquid water in the clay is a single‐valued function of the liquid water content, and that the ice has the properties of pure bulk ice, this curve also represents the relationship between freezing point depression and unfrozen water in the partially frozen clay. An equation for the heat capacity of a partially frozen soil was also derived. This equation was employed to calculate the heat capacities of the clay at different water contents and sub‐zero temperatures. A comparison of the calculated unfrozen water contents and heat capacities of the partially frozen Na‐Wyoming bentonite with the available experimental data indicated satisfactory agreement, especially as regards the unfrozen water contents.
Streamflow Fluctuation, Bar Roughness, and Bed Load Movement:A Hypothesis
Authors: Norgaard Richard B.
Published: February 2008

A relation between streamflow variables and bar conditions on the Lower Columbia River derived by linear regression analysis on U.S. Army Corps of Engineer and U.S. Geological Survey data leads to the hypothesis that bed‐load movement and bar scour are increased by streamflow fluctuation.
The Profile of a Random Stream
Authors: Dacey Michael F.
Published: February 2008

A probabilistic formulation is given for the profile of a stream. The elevation of a stream is considered at successive pointsj,j= 1, 2, · · ·, that have equidistant spacing along the stream. The basic assumptions of the model are (1) between thejth and (j+ l)th points stream elevation remains constant or drops by a unit of elevation, and (2) the probabilitypof decrease between thejth and (j+ l)th points is independent ofj. Two formulations of the model are examined by assuming thatpis constant throughout the stream length, and thatpis a random variable. The model is analyzed for these two cases, and results include the frequency functions, means, and variances of length of stream from its origin to ‘sea‐level’ and for elevation of stream at each pointj.
Permeability of Orthotropic Porous Mediums
Authors: Szabo Barna A.
Published: February 2008

The mathematical definition of permeability for orthotropic porous mediums is developed from the assumption that orthotropic porous mediums (i.e., porous mediums that possess three mutually perpendicular planes of structural symmetry) obey Darcy's Law in the three directions normal to the planes of symmetry. This assumption is shown to lead to the conclusion that permeability obeys the transformation law definitive of second‐order tensors; and that consequently a permeability quadric, the Mohr circle representation of transformation of permeability components and permeability invariants, can be defined.
Albedo of Intercepted Snow
Authors: Leonard Raymond E. , Eschner Arthur R.
Published: February 2008

Incident and reflected shortwave radiation above a red pine plantation was measured at 30‐minute intervals for two days after a 12‐inch snowfall. Maximum albedo was less than 20% of incident radiation, markedly lower than the 70–90% observed for fresh snow on the ground and commonly assumed to apply to intercepted snow. Thus, energy available for evaporation of intercepted snow may be 4 times greater than previously supposed. As intercepted snow ripened, albedo decreased and eventually approached summertime values once the snow left the upper part of the canopy.
Base‐Flow Recessions—A Review
Authors: Hall Francis R.
Published: February 2008

Hydrologists have studied base‐flow recessions for one hundred years or more. By the early nineteen hundreds much of the basic mathematical development was completed, and some methods of hydrograph analysis were known. Recent mathematical work, although repetitive to some extent of the earlier efforts, has the advantage that it assesses more closely the effects of the simplifying assumptions used to obtain solutions. Most workers have preferred to follow graphical or statistical rather than mathematical approaches. The reasons appear to lie mainly in problems caused by the assumptions and in difficulties in interpreting the real stream hydrograph. Also, base flow can come from numerous sources besides ground water. Other complications arise from the question of whether the basin response is linear or nonlinear, because the response is a function of various geologic and hydrologic factors in addition to those considered in the mathematical derivations.
Digital Simulation of Estuarine Water Quality
Authors: Dornhelm Richard B. , Woolhiser David A.
Published: February 2008

Partial differential equations describing the unsteady, one‐dimensional mixing process in an idealized homogeneous, linearly expanding estuary are presented and solved numerically, using an implicit finite‐difference scheme. These solutions portray the change in concentration of conservative substances with time and distance as a result of tidal fluctuations and variable inflow. Although the model presented is highly simplified in terms of estuarine geometry, experiments with varying boundary conditions can provide insight into the adequacy of the more commonly used quasi‐steady‐state models.
The demand for water: Some empirical evidence on consumers' Response to a commodity uncertain in supply
Authors: Turnovsky Stephen J.
Published: February 2008

Based on a theoretical model that studies how individuals respond to a commodity uncertain in supply, this paper estimates some demand functions for water in situations where supplies are known to be stochastic. The model is applied to data consisting of a sample of Massachusetts towns, separate functions being estimated for household and industrial demand. Two cross sections are estimated, one for 1962 and one for 1965, the beginning and the end, respectively, of the New England drought.

As far as household demand is concerned, price, uncertainty as measured by supply variance, and particularly housing space are significant, whereas for industrial demand only the first two variables are significant. The results also indicate that firms are more responsive than households to both price and uncertainty and that their response to uncertainty lessened as a result of the drought, an implication that agrees with the theoretical model.
Determination of the ground‐water component of peak discharge from the chemistry of total runoff
Authors: Pinder George F. , Jones John F.
Published: February 2008

The ground‐water component of stream discharge may be determined from the chemical characteristics of the stream water. A chemical mass‐balance is used to relate total, direct, and ground‐water runoff. To solve the mass‐balance equation, it is necessary to estimate the chemical composition of the ground‐water and direct‐runoff components. The solute concentration of ground water is determined from total runoff during baseflow; the chemical characteristics of direct‐runoff are estimated from samples of total runoff collected from selected locations in a basin during peak discharge periods. In three small watersheds in Nova Scotia ground‐water runoff constituted from 32 to 42% of peak discharge for the period of analysis.
Elects of Hurricane Storms on Agriculture
Authors: Hartman L. M. , Holland David , Giddings Marvin
Published: February 2008

Hurricane storms as they move inland are accompanied by rather widespread rainfall. The effect of the rainfall on crop production depends upon the time occurrence of the storm. A statistical time series analysis of the relation between rainfall by time periods and crop yields indicates that rainfall during the major hurricane season (August, September, and October) is damaging to many crops. The analysis consisted of a multiple regresssion of crop yields on rainfall by ten‐day time intervals. The total benefit or loss from any storm would depend upon the time occurrence and the track of the storm. A summary of change by states in total crop value from one inch of incremental rainfall for their five major crops resulted in both positive and negative totals, depending upon the time period. Predicted changes in yield and crop value for three historic storms indicate net losses for two storms occurring in August and September and net benefits for one storm occurring in July.
Antitranspirants Research and Its Possible Application in Hydrology
Authors: Davenport David C. , Hagan Robert M. , Martin Paul E.
Published: February 2008

Research on antitranspirants may have application in increasing the yield of water from watersheds by reducing transpirational losses from vegetation under certain environmental conditions. There are three broad groups of antitranspirants: (1) reflecting materials that decrease the heat load on the leaf. (2) film‐forming materials that hinder the escape of water vapor from the leaf, and (3) stomata‐closing materials that increase stomatal resistance. Antitranspirants are most effective in decreasing transpiration when other resistances in the passage of water to the roots, through the plant, and to the atmosphere are not great, when there is good coverage of the stomatal bearing leaf surfaces (except for reflecting materials), when new foliar growth following treatment is minimal, and when optimum concentrations and application rates are used.
The Linear Decision Rule in Reservoir Management and Design: 1, Development of the Stochastic Model
Authors: Revelle Charles , Joeres Erhard , Kirby William
Published: February 2008

With the aid of a linear decision rule, reservoir management and design problems often can be formulated as easily solved linear programing problems. The linear decision rule specifies the release during any period of reservoir operation as the difference between the storage at the beginning of the period and a decision parameter for the period. The decision parameters for the entire study horizon are determined by solving the linear programing problem. Problems may be formulated in either the deterministic or the stochastic environment.
Diffusion of Trapped Gas from Porous Media
Authors: Adam Kenneth M. , Bloomsburg George L. , Corey Arthur T.
Published: February 2008

When a gas‐filled porous medium is permitted to imbibe liquid from a source at a pressure equal to the initial gas pressure, some of the gas is trapped in the pores and is discontinuous with the atmosphere surrounding the medium. The amount of gas initially trapped varies over a range at least as wide as from about 5 to about 50% of the pore volume. The percentage of trapped gas is gradually reduced to zero as the gas diffuses away under the influence of capillary compression. This happens even though the imbibed liquid is presaturated with the gas initially trapped. Porous media become completely saturated with liquid first at exposed surfaces, and the zone of complete saturation moves continuously toward the interior.
Clogging in Surface Spreading Operations for Artificial Ground‐Water Recharge
Authors: Behnke Jerold J.
Published: February 2008

Clogging is a complex phenomenon dependent upon many variables. For the conditions studied it is essentially a surface‐sealing process. When turbid water contains a range of grain sizes, clogging is initiated by the deposition of a surface layer that is graded because of the gravitational segregation of heavier particles. Most of the clogging results from the straining of finer particles from the flowing water by the graded depositional layer. An equation was developed which predicts accumulated water quantity versus time relationships for several concentrations of a specific turbidity. Even coarse‐grained porous media clogged at turbid water concentrations as low as 50 ppm.
A Note on Moran's Probability Theory of Dams and Storage Systems
Authors: Venetis C.
Published: February 2008

The distribution of the reservoir content is examined (discrete time, continuous state space) for constant release continuous during the time interval (t, t + 1). Empty and full reservoir probabilities are expressed by the Dirac delta function. The distribution of the reservoir content at time t + 1 is obtained from that at time t by convolution, taking into account the constraints in the range of variation of the content of the finite reservoir that may not meet the demand. The case of nonzero probabilities of zero inflows is briefly discussed, and the equations for the discrete case are derived from those of the continuous by substituting summations for the integrals.
Anisotropie Permeability of Fractured Media
Authors: Snow David T.
Published: February 2008

The mathematical equivalents of parallel plate openings are used to simulate real fractures dispersed in orientation, distributed in aperture, and of arbitrary spacing. With this idealization of jointed pervious rock, the discharge of each conductor is a second rank tensor proportional to the cube of aperture and to the projection of a hydraulic gradient generally parallel to no conductor. One may add components of discharge through each intersecting conductor and components of discharge through intervening pervious blocks. The reciprocal of specific surface of the fracture system like spacing serves as a weighting factor for the tensor sum, which is the anisotropic Darcy's law permeability of an equivalent continuous medium.

Special cases of one, two, and three joint sets are modeled by applying Monte Carlo methodsto pair orientations of individual planes sampled from Fisher dispersions with apertures sampledfrom skewed normal distributions. Statistics of the orientation of principal axes and ofprincipal permeabilities are developed to show the relationship between joint geometry andanisotropy and to assess its variations.
Upconing of Fresh Water—Sea Water Interface Below Pumping Wells, Field Study
Authors: Schmork S. , Mercado A.
Published: February 2008

Field investigations on the upconing mechanism of interface under the influence of pumping were carried out to check the validity of the existing theoretical formulas, to study the salinization of pumped water as related to the position and characteristics of the interface, and to provide some analytic design procedures for skimming fresh water from above saline water bodies. It was found that the existing theoretical formulas describing the upconing interface are in agreement with field results up to some critical rise of the interface, which seems to be approximately half the distance between the bottom of the well and the undisturbed interface. In addition, the use of the linear approximation for the dispersion pattern was justified as a first approximation of the resultant transition zone. The salinization of the pumped water is probably caused by the intrusion of saline water above a certain critical depth. From correlation analysis, the salinity increase of pumped water is about 5 to 8% of the average salinity of the saline water intruded above the critical depth. The average salinity above the critical depth is determined by the existing formulas corrected for dispersion. Design procedures based both on theoretical formulas and field investigations are summarized in the form of nomograms. These nomograms were constructed on the assumption that the mixing mechanism for other geometries is similar to the observed one.
Weather and Diurnal Frozen Soil Structure at Charlottesville, Virginia
Authors: Outcalt Sam I.
Published: February 2008

The results of a field study of weather conditions and diurnal frost structures demonstrate the effect of the atmospheric environment on the structure of soils at a site where soil water content was not a limiting factor. Statistical discrimination of soil freezing and frozen soil structures is often made possible by using late afternoon sky and dew‐point temperature data. An evolutionary classification of three typical frozen soil structures is also presented.
Determination of soil density and water content by fast neutrons and gamma rays
Authors: Corey J. C. , Boulogne A. R. , Horton J. H.
Published: February 2008

Sequential measurements of gamma and fast neutron attenuation were used for nondestructive determination of both soil density and water content of soil samples. Soils containing known amounts of water were packed into 22.5‐cm diameter cylinders to a depth of ∼9 cm. Measurements were made of attenuation of fast neutrons from a 3‐μg 252Cf source and attenuation of gamma rays in a collimated beam from a 137Cs source. The attenuation was used to calculate the soil density and water content of these samples. The mean difference between the calculated and known water contents was 0.006 g/cm3 with a standard deviation of 0.010 g/cm3; the mean difference for soil density was 0.010 g/cm3 with a standard deviation of 0.017 g/cm3. Calculations based only on counting statistics show that an attenuation method using a combination of gamma and fast neutrons is better than a method using two gamma energies.
Some Finite Difference Solutions for the Dispersion of Thermal Sources in Steady Prismatic Flow
Authors: Ahlert R. C. , Biguria G. , Tarbell J.
Published: February 2008

Mathematical models and numerical difference techniques simulate the dispersion of heated effluents in steady, prismatic flow. Isovelocity point and line sources of finite volumetric flow develop in a short‐time region of the order of two depths. Dispersion of plane sources and developed sources of the former type occurs in a longtime regime and is variable in two dimensions with respect to both velocity and diffusivity. Short‐time solutions serve as input to a general longtime finite difference scheme. Flow mechanics control dispersion in typical problems employing point and plane source configurations.
A Model of Surface Crusting and Infiltration of Bare Soils
Authors: Seginer Ido , Morin Joseph
Published: February 2008

An infiltration equation was derived on the assumption that a drop upon impact with the soil compacts into final crust structure a small area. The size of this area is characteristic of the drop and the soil properties. Extensions of this model can treat spectrums of drops and variations of rainfall characteristics with time. The model applies to initially saturated homogeneous soil columns and leads to the conclusion that the reduction of infiltration capacity is not directly related to time but rather to the number of drops that hit the surface. The effect of the depth of the soil column on the final infiltration capacity is such that the deeper it is, the higher the final infiltration capacity, approaching a limit, which depends on the properties of the crust, not of the subsoil. It is suggested that comparisons between infiltration experiments in columns be made on the basis of the intrinsic value of the limiting infiltration capacity.
Water Use by Salt Cedar
Authors: van Hylckama T. E. A.
Published: February 2008

Six years of observations on water use by salt cedar, conducted in a battery of evapotranspirometers, or tanks, have shown that thinned out stands use nearly as much water as control tanks if the water is of good quality. It is concluded that the method of making a vegetation survey and then extrapolating water use as measured in evapotranspirometers to a 100% density can lead to serious overestimation of water use. Thinning and cutting are ineffective methods of saving water. In cutoff stands, under favorable conditions, shoots can increase in length by as much as 5 cm per day. Only a few plants such as bamboo and cucumber are reported to grow faster than that. The assumption that phreatophytes always transpire at a potential rate is not sustained by the facts presented in this paper. When differences in depth to water as small as 1.5 to 2.1 meters and 2.1 to 2.7 meters affect the water use, it seems reasonable to conclude that with a water table at four meters for instance (a situation not unusual along dry river beds), salt cedar still may thrive but use comparatively little water, and the claims as to the quantity of water potentially saved by their eradication could well be overestimated.
Numerical Modeling of Unsaturated Groundwater Flow and Comparison of the Model to a Field Experiment
Authors: Green Don W. , Dabiri Hassan , Weinaug Charles F. , Prill Robert
Published: February 2008

A mathematical model describing isothermal, two‐phase flow in porous media has been developed. The model, which consists of describing differential equations and algorithms for their numerical solution, was applied to the problem of vertical groundwater movement in unsaturated soils in the absence of evaporation and transpiration. The equations describing water‐air flow through porous media are second order, nonlinear partial differential equations. These equations were converted to finite difference form and were solved with the aid of a digital computer using an iterative implicit procedure. The model includes effective permeabilities of each phase and capillary pressure as functions of liquid saturation. The properties of the porous media may be varied in the model as functions of position. A comparison was made between computed results and experimental field data on moisture movement beneath a shallow surface pond. Water was added to the pond at controlled rates to maintain an approximately constant head for a set time period. Following this wetting period the pond was kept dry, but covered to reduce evaporation. At different times during the wetting and drying periods, neutron logs were run to measure water saturation versus depth at depths of up to 22 feet. The experiment was simulated with the computer model and excellent agreement between calculated results and the data was obtained; thus the mathematical model could be used to describe soil moisture movement during wetting and drying periods.
P‐N Junctions—A Tool for Temperature Measurement
Authors: Enfield Carl G. , Tromble John M.
Published: February 2008

Silicon semiconductors were investigated for use as temperature transducers (−25°C → +75°C), and were found to have good stability, linearity, and high sensitivity. When one ma of forward current was applied to a diode, a sensitivity of approximately 1.9 mv/°C was obtained with a forward voltage drop of approximately 600 mv.
A Modification of the Benzene Synthesis Method for Tritium Analysis
Authors: Wallick Edward I. , Knauer George A.
Published: February 2008

A modification of the benzene synthesis method for tritium analysis by liquid scintillation counting is suitable for limited production of hydrologic samples and has a lower detection limit of 10 TU (1 TU = 10−18 T/H). Procedures are described for elimination of sulfide quenching of the benzene and optimization of the acetylene‐benzene conversion. Tritium isotopic fractionation is constant during benzene synthesis with a loss of (19.3 ± 0.2)% of the water sample tritium activity. Cross checks with other laboratories agree within counting statistical error.
Optimum Operating Procedure for a River Gaging Station Established To Provide Data for Design of a Water Supply Project
Authors: Moss Marshall E.
Published: February 2008

A scheme for determining the optimum length of streamflow record and the optimum frequency of discharge measurement has been applied to the gaging station on Arroyo Seco, an intermittent stream near Soledad, California. If the streamflow record is used only in the design of a water supply reservoir at the gage site, the optimum record length is found to vary between 9 and 56 years, depending on nonhydrologic time constraints. The optimum frequency of measurement of discharge for calibration of the station rating curve is found to be indeterminate. Sensitivity analysis indicates that the optimum length of record is more sensitive to the variability of the streamflow and the planned level of development at the site than to discount rate or cost of obtaining streamflow data.
Lithologic Controls on the Development of Solution Porosity in Carbonate Aquifers
Authors: Rauch Henry W. , White William B.
Published: February 2008

Movement of ground water in maturely karsted limestone aquifers is commonly through solution conduits of considerable size. The object of this study was to determine the lithologic controls on the distribution of conduits within a heterogeneous sequence of carbonate rocks. The volume of all accessible caves more than 100 feet in length in the Nittany Valley area of central Pennsylvania was measured. Most caves are entirely within limestones, cave development in dolomite is extremely rare. Within the limestone sequence the bulk of the cave volume is concentrated in a few members. Chemical and petrographic analyses of the carbonate rocks were associated with cave volume by bar graphs and components analyses. The more cavernous limestones seem to be those with low amounts of dolomite, clay, and other impurities, and a high micrite grain fraction. Coarse limestones and dolomites are less cavernous.
Selection of Frequency Distribution Models
Authors: Gupta Vulli L.
Published: February 2008

A method is considered for selecting mathematical models to fit frequency distributions of hydrologic data among ten commonly used methods of frequency analysis. The methods are those of Gumbel, Lieblein, Chow, and the seven types of Gringorten. The best fitting model is chosen on the basis of comparison for goodness of fit indicated by the coefficients of determination. Friedman's nonparametric statistical test was employed to detect significant differences between the models.
Partial Area Contributions to Storm Runoff in a Small New England Watershed
Authors: Dunne Thomas , Black Richard D.
Published: February 2008

During an experimental study of runoff producing mechanisms in a small drainage basin, the major portion of storm runoff was produced as overland flow on a small proportion of the watershed. Where the water table intersected the ground surface before and during a storm, water escaped from the soil surface and ran quickly to the stream at velocities 100 to 500 times those of the subsurface system. Direct precipitation onto the saturated area was another major contributor of storm flow. Storage of water within these source areas was small and travel times out of them were short. Runoff from them was largely controlled by rainfall intensity. These partial areas contributing quick runoff could expand or contract seasonally or during a storm. Their position and expansion can be related to geology, topography, soils, and rainfall characteristics. In the study basin, water that remained below the ground surface on its way to the main stream channel was a relatively minor contributor to the storm hydrograph. The response of subsurface flow to rainfall was heavily damped by storage and transmission within the soil. Measurements of water table elevation and runoff from experimental plots in another small watershed with different geologic conditions confirmed the results outlined above. Runoff records from a large number of small basins of the Sleepers River experimental watershed indicate the more general applicability of these findings.
Variational Principles for Confined and Unconfined Flow of Ground Water
Authors: Neuman Shlomo P. , Witherspoon Paul A.
Published: February 2008

Finite element techniques are being employed to an increasing degree in solving complicated groundwater flow problems, including problems with a free surface. These methods usually rely on the development of appropriate variational principles. This paper presents several such principles for both confined and unconfined flow.
Some Behavioral Characteristics Associated with Residential Water Price Changes
Authors: Hanke Steve H.
Published: February 2008

The specific types of change in residential water‐user behavior after the installation of meters are described for a sample of residential customers from Boulder, Colorado. The major types of response in order of sample frequency were (1) watching sprinklers more carefully, (2) ceasing to sprinkle parts of the yard, (3) permitting the yard to turn brown, (4) watering at night, (5) repairing outside leaks, (6) repairing inside leaks. The survey showed that 71% of the sample showed some interest in water matters and that, ex post, 58% would prefer not to be metered with restrictions being imposed as necessary. The conservation practices of 58% of the sample population intensified over time.
Benefit‐Cost Analysis and Multiple Objectives: Current Issues in Water Resources Planning
Authors: Freeman A. Myrick , Haveman Robert H.
Published: February 2008

Basic principles of multiple objective planning are discussed. The need for careful, nonoverlapping, empirically measurable definitions of each objective is brought out. The limits placed on multiple objective planning by the absence of a set of social weights are pointed out, and the possibility of deducing these weights from congressional actions is discussed. The regional development objective receives particular attention.
Comparing Power Spectra Computed by Blackman‐Tukey and Fast Fourier Transform
Authors: Edge Billy L. , Liu Paul C.
Published: February 2008

Since controversy has arisen as to whether the Blackman‐Tukey or the fast Fourier transform (FFT) technique should be used to compute power spectra, single and cross spectra have been computed by each approach for artificial data and real data to provide an empirical means for determining which technique should be used. The spectra were computed for five time series, two sets of which were actual field data. The results show that in general the two approaches give similar estimates. For a spectrum with a large slope, the FFT approach allowed more window leakage than the Blackman‐Tukey approach. On the other hand, the Blackman‐Tukey approach demonstrated a better window closing capability. From these empirical results it is concluded that the Blackman‐Tukey technique is more effective than the FFT approach in computing power spectra of short historic time series, but for long records the fast Fourier transform is the only feasible approach.
Groundwater Thermal Regime in a Glacial Complex
Authors: Parsons Myles L.
Published: February 2008

Numerical simulation of the groundwater thermal regime in a glacial complex in the northern Ontario clay belt and numerical modeling of a hypothetical groundwater basin suggest that groundwater flow has a significant effect on the subsurface temperature field. Borehole temperature measurements reflect the hydrogeologic contrast between the highly permeable eskerine deposits and the adjacent less permeable clay and till strata. The eskerine groundwater is several degrees warmer and possesses lower spatial temperature variations than does the clay‐till groundwater. Numerical simulation of the temperature field indicates that the temperature variations are related to differences in thermal conductivities of the flow media, to variations in the magnitude of the groundwater flux between esker and clay‐till flow systems, and to spatial variations in the water table temperature. The latter factor probably reflects contrasting surface cover conditions between the sandy eskerine terrain and the organic terrain of the clay plain.
Sampling Considerations in Stream Discharge and Temperature Measurements
Authors: Quimpo Rafael G. , Yang Jing‐Yea
Published: February 2008

The choice of a sampling interval in hydrometry is constrained by two extremes, redundant information from sequentially correlated observations resulting from sampling too often, and lost information because of too infrequent sampling. The variability of the sample variance is used to obtain a sampling interval at some level of information redundance. This statistic is suggested as an alternative measure of information content to the one based on the variance of the sample mean. Time series of stream discharge and temperature measurements are used to illustrate application of the theory.
Spacing of Drainage Wells in a Layered Aquifer
Authors: Khan Muhammad Yunus , Kirkham Don
Published: February 2008

A theory is presented to determine spacing of identical drainage wells that, by discharging groundwater simultaneously from a layered aquifer, will lower a water table to a preassigned level and maintain it. The theory has been developed by solving a mathematical boundary value problem. The wells are located on a certain regular grid, and the aquifer receives a uniform vertical recharge from rainfall or excess irrigation. The theory shows that the spacing depends on the thickness and hydraulic conductivity of each permeable layer tapped by the wells, the maximum allowable drawdown, the uniform vertical recharge, the radius of the wells, and the well grid geometry. A table of values of a function, useful for determining spacing of wells to be tapped in an aquifer that may consist of any number of permeable layers, is given.
Benefits and Beneciaries: Contrasting Economic and Cultural Distinctions
Authors: Smith Courtland L. , Hogg Thomas C.
Published: February 2008

People and their values are the basic elements of social and cultural systems. To understand adequately the significance of benefit‐cost ratios used in water resource development project justification, knowledge of the people involved is required, as well as recognition that benefit‐cost decision making is part of a set of cultural values governing relationships among people. Comparative observations of peoples of the Salt River valley of Arizona, the Pacific Northwest, and the Kalahari desert of Africa suggest new areas of questioning relative to people's role performance and their cultural values in resource development. These observations show interesting differences in the nature of role performance relative to receiving water resource development benefits and repaying the cost of creating these benefits, and significant differences in the cultural values for obtaining water resource development.
Discrete Differential Dynamic Programing Approach to Water Resources Systems Optimization
Authors: Heidari Manoutchehr , Chow Ven Te , Kokotović Petar V. , Meredith Dale D.
Published: February 2008

The optimization of operating policies of multiple unit and multiple purpose water resources systems by traditional dynamic programing with the use of high speed digital computers encounters two major difficulties: memory requirements and computer time requirements. This paper presents an iterative method that can ease the above difficulties considerably. The method starts with a trial trajectory satisfying a specific set of initial and final conditions and applies Bellman's recursive equation in the neighborhood of this trajectory. At the end of each iteration step a locally improved trajectory is obtained and used as the trial trajectory in the next step. The method has proved particularly effective in the case of so‐called ‘invertible’ systems. The merits of the proposed approach are demonstrated through its application to a four‐unit, two‐purpose water resources system. To save computer time the example is restricted to deterministic inflows.
An Automatic Outflow Measuring Device
Authors: Sharma M. L. , Bawden R. A.
Published: February 2008

A device for continuous and accurate measurement of very small quantities and slow rates of water flow is described. Drops of uniform size are formed and counted instantaneously by digital counters as they fall between pairs of electrodes. The counts and time are recorded by automatically photographing the counters and a clock at suitable time intervals.
Evapotranspiration and Energy Balances of Forest and Field
Authors: Tajchman S. J.
Published: February 2008

The energy and water balance components of a 70‐year‐old Norway spruce forest, a 2‐year‐old alfalfa field, and a potato field near Munich, Germany, were computed for the period May–October 1965 by using hourly averages of metorologic parameters. Turbulent diffusion and energy budget methods were used to determine evapotranspiration and convective exchange. The two methods yielded satisfactory, agreement for the low crops but not for the forest. The mean seasonal albedo values for the potatoes and the alfalfa were 0.18 and 022, respectively. The albedo of the forest was obtained for 1 day and averaged 0.05. The shortwave incoming radiation over the forest was 12% less than that over the fields. The net shortwave radiation over the forest was 2 and 7% greater than that over the potatoes and the alfalfa, respectively, whereas the long wave emission from the forest was 22 and 15% less than that from the potatoes and the alfalfa, respectively. The total net radiation over the forest was 20% greater than that over the alfalfa and 16% greater than that over the potatoes. Sensible heat flux from the forest was 2.6 and 1.6 times greater than that from the alfalfa and the potatoes, respectively. Evapotranspiration from the forest was 4% less than that from the alfalfa but 14% greater than that from the potatoes. The roughness lengths of the forest and the fields were about 0.1 of their heights. The zero plane displacements were 0.71 and 0.5–0.6 of the heights of the forest and the crops, respectively. The exchange coefficient at the top of the trees was about 100 times as large as that at the tap of the crops. The water supply in the soil was not limiting on any of the three experimental sites during the vegetation period.