bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid flow in the Western Canada Sedimentary Basin: 2. Effect of geology
Authors: Hitchon Brian
Published: February 2008

The observed effect of variations of geology on the fluid potential distribution is treated by considering the three‐dimensional flow net by stratigraphic units. Hydraulic head distribution maps for 27 stratigraphic units in the western Canada sedimentary basin were prepared, and those from the Upper Devonian Beaverhill Lake Formation, Woodbend and Wabamun Groups and the Lower Cretaceous Mannville Group and Viking Formation are illustrated. The low fluid‐potential drain that exists within the Upper Devonian and Carboniferous carbonate rocks itself contains drainage channels belonging to different fluid potential subsystems. Excellent examples of these subsystems are found in the carbonate reef complexes of the Beaverhill Lake Formation and the Woodbend Group. Drawdown of the fluid potentials by some of the low fluid‐potential channels is reflected through up to 2500 feet of strata and across a major unconformity. In general, relatively highly permeable beds significantly affect the regional fluid potential distribution, although the dominant features are topographically controlled. An apparently three‐dimensionally closed hydraulic head low in the Viking Formation is most probably the result of a chemico‐osmotic potential coupled with the regional elevation and pressure potential.
Water Yield Changes after Converting a Forested Catchment to Grass
Authors: Hibbert A. R.
Published: February 2008

A 22‐acre catchment in the southern Appalachians was cleared of hardwood forest in 1958 and 1959 and seeded to Kentucky 31 fescue grass in 1959 and 1960. The amount of evapotranspiration by the grass cover was closely related to the amount of grass produced. During years when grass production was high, water yield from the catchment was about the same as or less than the expected yield from the original forest. As grass productivity declined, water yield gradually increased until it exceeded the predicted yield from the forest by over 5 inches annually. The grass appeared to evaporate more water early in the spring and less water late in the summer than the original forest cover.
Effects of Boundary Conditions of Models on Tracer Distribution in Flow through Porous Mediums
Authors: Gershon N. D. , Nir A.
Published: February 2008

Effects of initial and boundary conditions on the distribution of the tracer in time and distance are calculated for several one‐dimensional systems (infinite, semi‐infinite, and finite) of tagged liquid flowing through a solid matrix, and the effects of hydrodynamic dispersion, diffusion, radioactive decay, and simple chemical interactions of the tracer are included. Exact and approximative solutions show that in most practical conditions the results of steady state experiments are influenced only up to 0.5% by changes in boundary conditions. In nonsteady state, results are influenced up to 5% in the region c/co ≃ 0.5, where c/co is the ratio of the measured concentration and the concentration of the solution entering the porous medium. Results are given in nondimensional form with graphs of representative cases.
A numeric method for estimating infiltration, redistribution, drainage, and evaporation of water from soil
Authors: Hanks R. J. , Klute A. , Bresler E.
Published: February 2008

A general numeric method is described for estimating one‐dimensional infiltration, redistribution, evaporation, and drainage of water from soil. The type of flow is determined by the water flux at the surface of soil or the bottom boundary. The method provides for hysteresis in the water content‐pressure head relation. Comparison with measurement made on soil columns for infiltration, redistribution, and evaporation were made. Good agreement was obtained between measured and computed values.
Effects of cultivation and grass on surface runoff
Authors: Dragoun Frank J.
Published: February 2008

Results of research show the effect of drastic changes in land use on surface runoff from 4‐acre watersheds near Hastings, Nebraska. Surface runoff was significantly reduced two years after converting marginal cultivated fields to perennial grass and was equivalent to runoff from native meadow after the third year. Conversely runoff increased greatly the first year after native meadow was placed in cultivation. The significance of these results is evident in the conversion of more than a million acres of marginal cropland to permanent vegetation in the Great Plains and in the proposed conversion of many more acres.
Modified Rubey's Law accurately predicts sediment settling velocities
Authors: Watson Richard L.
Published: February 2008

Modification of viscous drag and the pressure drag terms in Rubey's theoretic equation for settling velocity of sand grains with two empirically determined constants results in the following formula

urn:x-wiley:00431397:media:wrcr583:wrcr583-math-0001
which predicts accurately the setting velocity of groups of sand grains measured with the Woods Hole rapid sediment analyzer. The following equation is a solution of Rubey's modified general equation that can be used to calculate the diameter of a particle or group of particles if the settling velocity for the particle is known:

urn:x-wiley:00431397:media:wrcr583:wrcr583-math-0002
Benefit‐Cost Ratios for Projects in Multiple Objective Investment Programs
Authors: Major David C.
Published: February 2008

Investment programing for multiple objectives rather than simply for the traditional water resource investment objective of increasing the national income has become an important new element in water resources planning in the United States. Reference is made to current multiple objective planning efforts, and the relevant theory is briefly explained. The benefit‐cost ratio appropriate to projects in multiple objective programs is presented, and it is shown how this ratio differs from the ratios required by current federal instructions, which do not allow agencies to reflect accurately the interaction of social preferences and investment opportunities. A change in the federal instructions is recommended.
Determination of Optimal Flood Protection Levels With Small Exceedance Probabilities
Authors: Shane Richard M. , Gaver Donald P.
Published: February 2008

A technique for selecting flood protection levels that exceed mean flood intensities by a large amount is based on a probability model derived from the assumption that base flow floods occur at random with exponentially distributed magnitudes. It is a parametric approach involving the estimation of two statistical parameters by the method of maximum likelihood. The sensitivity of the results to errors made in choosing the correct flood intensity distribution is examined by computing the loss when the flood intensities are log normally distributed. This loss is shown to be small over a wide range of parameter values likely to be encountered. Through the use of a quadratic loss function it is shown that the expected loss is inversely proportional to the length of record. Furthermore if the existing level of protection exceeds the mean peak flood intensity by a large amount, then parameter estimation losses can be quite large, even when a record of considerable length is available. The quadratic loss function also demonstrates that the loss is due primarily to errors in estimating the expected flood intensity.
Estimation of the Parameters of Gumbel's Third Asymptotic Distribution by Different Methods
Authors: Deininger Rolf A. , Westfield James D.
Published: February 2008

Estimation of the parameters of Gumbel's third asymptotic distribution of the smallest value has been accomplished in the past by the following methods: (1) the method of moments; (2) using an order statistic on the characteristic drought; and (3) using the smallest observed drought. These three methods are compared with a fourth method that uses sequential least squares and a Fibonacci search. Based on estimates of the parameters of 44 rivers in the United States, it appears that methods 1, 2, and 3 do not give a satisfactory estimate of the smallest drought in a large number of cases. The method of using an order statistic was the least successful. The use of the least squares and Fibonacci search approach gave more acceptable estimates than the other methods.
A Peak Discharge Relation for Intermediate Drainage Basins
Authors: Watt W. E. , Kennedy R. J.
Published: February 2008

For ungaged drainage basins of intermediate size, a peak discharge‐frequency relation may be determined from a frequency distribution of rainfall excess and a method for relating peak discharge to rainfall excess. For short‐period hydrographs a one‐parameter peak discharge relation employing the basin lag to is satisfactory. The suggested relation is QP = CV/to. If to is expressed in hours and QP/V is expressed in cfs per square mile‐inch, the expression becomes QP/V = 645C/to, where C on theoretical grounds varies between 0.74 and 1.05. Analysis of the records of 45 isolated intense storms on 12 drainage basins in southern Ontario provided satisfactory confirmation of the above relation with C equal to unity.
An Economically Meaningful and Workable System for Calculating Flood Insurance Rates
Authors: Kunreuther Howard , Sheaffer John R.
Published: February 2008

The passage of the Flood Insurance Act of 1968 [U.S. Congress, 1968] has set the stage for the inclusion of flood insurance as a viable floodplain management alternative. As of March 1969, insurance is being marketed in parts of five urban areas: Fairbanks, Alaska; New Orleans, Louisiana; Alexandria and Arlington, Virginia; Matewan, West Virginia and Baytown, Texas. The program determines rates in the following fashion.

Preparatory to determining rates, three sets of information are established:

1. Profile of the 100‐year flood.

2. A stage‐frequency curve.

3. Depth‐percent damage curves by class of structure. (At present, policies are only written for 1–4 family residences so that the number of classes is limited. Rate tables have been developed for the following classes of structures: (a) one‐story, no basement; (b) two‐story, no basement; (c) one‐story with basement; (d) two‐story with basement; and (e) tri‐level.)
A System for Measuring Total Sediment Yield from Small Watersheds
Authors: Brown Harry E. , Hansen Edward A. , Champagne Norman E.
Published: February 2008

Design and calibration data are presented from eight sediment measuring installations that have been constructed and tested by the U.S. Forest Service on the Beaver Creek pilot watershed in Arizona. Each installation includes a low dam and basin to trap coarse sediments and a series of splitters that collect a representative portion of the suspended sediment leaving the basin. The first splitter, a Barnes runoff sampler, is a sharp edged slot extending downstream from the dam spillway. With a 12‐foot‐wide spillway it extracts a theoretical split of 1/600 of the total volume of flow. The second splitter, an inclined slot mounted at the lower end of the Barnes sampler, extracts a theoretical 0.1 sample. This sample, 1/6000, enters an intermediate storage tank that leads from the middle of the stream channel to a final storage tank on the bank. The third splitter is a single slot, extracting a 0.1 sample, mounted below a small rectangular weir in the end of the intermediate tank. The slot, which carries a 1/60,000 sample, enters the final storage tank. Calibration data are presented to characterize sampler performance, and a procedure is outlined for calculating total sediment yield. Errors in estimating total sediment are usually less than 18%.
The nth Root Normal Distribution of Precipitation
Authors: Stidd Charles K.
Published: February 2008

A computer generated ‘stationary time series’ has been modified by processes analogous to those that produce precipitation. The resulting numbers have the distributional characteristics of precipitation data. A quantitative explanation is thereby obtained for the skewness in precipitation distributions and the nth root normal distribution is verified.
Streamflow Changes after Forest Clearing in New England
Authors: Hornbeck J. W. , Pierce R. S. , Federer C. A.
Published: February 2008

Clearing a hardwood forest cover and preventing regrowth with herbicides on a 39‐acre watershed in central New England increased annual water yield an average 12.2 area‐inches for the first two water years after treatment. Most of this increase occurred during the critical low flow months of June through September, and the amount was governed in large part by rainfall in this period. There was a small advance of snowmelt runoff and a consistent increase in growing season high flow values. Our data agree with others showing that sizeable streamflow increases can result from forest clearing in the uplands of the eastern United States.
Post‐Irrigation Movement of Soil Water: 2. Simultaneous Redistribution and Evaporation
Authors: Gardner W. R. , Hillel D. , Benyamini Y.
Published: February 2008

Water content measurements by γ‐ray attenuation were made on soil columns during simultaneous redistribution and evaporation following irrigation. Redistribution is shown to reduce evaporation, in some cases appreciably. For a deep irrigation the redistribution proceeds at a rate that is relatively independent of the evaporation process, as has been predicted from numerical solutions of the flow equation. Expressions are derived for obtaining an estimate of amount of reduction in evaporation due to redistribution when the redistribution rate is known.
The Friction Coefficient for Shallow Flows over a Simulated Turf Surface
Authors: Phelps H. O.
Published: February 2008

An incomplete understanding of the friction coefficient of rough surfaces is one of the limiting factors in the application of the basic momentum and continuity equations to the modeling of overland flow. Experiments on steady, uniform flows in the laminar and transitional regions over a simulated turf surafce provide the data required to investigate the general hydraulic roughness properties of natural turf, and the particular parameters that are likely to influence the friction coefficient. Since boundary geometry depends on flow depth, it is erroneous to disregard this factor when considering the relationship between friction coefficient and Reynolds number. By maintaining constant depths while varying the Reynolds number, the separate effects of boundary geometry and Reynolds number on the friction coefficient are demonstrated. The results, which are presented in the form of a friction coefficient chart, may be rationally explained if the simulated turf is considered to be a complex porous medium in which the boundary geometry is variable.
Modeling the Effect of Land Use Modifications on Runoff
Authors: Onstad C. A. , Jamieson D. G.
Published: February 2008

The natural apportionment of rainfall excess to surface and subsurface flow can mean the difference between large flow rates for a short time or more manageable flow rates over a longer time. By using available soil storage, peak flood flows can be reduced without necessarily reducing the total volume of runoff. An attempt has been made to simulate this phenomenon. The land phase of the hydrologic system has been simulated by a series of interconnected, nonlinear reservoirs and the channel phase by a single linear reservoir. By manipulation of parameters, which mathematically represent physical measurements, the watershed response to the addition of conservation practices, such as terracing, may be predicted.
Leaching of Crop Residues as a Source of Nutrients in Surface Runoff Water
Authors: Timmons D. R. , Holt R. F. , Latterell J. J.
Published: February 2008

Nitrogen and phosphorus losses were determined in plant leachates from alfalfa, Kentucky bluegrass, barley straw stubble, and oats straw stubble. Plant samples harvested from the field were either leached immediately or were desiccated by drying or freezing before leaching. The extraction of soluble nitrogen and soluble phosphorus in leachates from alfalfa and bluegrass was greatly increased by drying or freezing. These same treatments, however, released only small amounts of soluble phosphorus from barley and oats straw. Estimated soluble nutrient losses indicate that leaching of alfalfa and bluegrass by surface runoff water could contribute substantial amounts of nitrogen and phosphorus to lakes and streams.
Fluid Travel Time between a Recharging and Discharging Well Pair in an Aquifer Having a Uniform Regional Flow Field
Authors: Grove D. B. , Beetem W. A. , Sower F. B.
Published: February 2008

Equations describing steady state flow between a recharging‐discharging pair of wells in a confined aquifer having a uniform regional flow field have been used to obtain a computer solution for the travel time of fluid along streamlines connecting the two wells. The time required for a contaminant or a tracer material to travel from the recharging well to the discharging well, and the timewise variation in concentration of the contaminant can be read directly from generalized plots of the computer solution.
Water Resource Management in Arid Environs
Authors: Cummings R. G. , Winkelman D. L.
Published: February 2008

The intertemporal problem of conjunctive management of a reservoir and an aquifer in an arid environment is the central theme of this paper. The model formulated focuses on several interrelated questions associated with maximizing a benefit function based on agriculture production with given stocks of water and expected water receipts, namely, the optimum pattern of land use and production, the optimum intertemporal allocation of water, and the optimum rate of investment in capital for water distribution. Periodic extractions of water from the reservoir and the aquifer are carried to the point where the value of water in current use equals the marginal expected value of water stored in each stock. The marginal expected storage value of the reservoir stock is discounted by water losses as well as by interest rates. We also show that the optimum rate of investment is that determined by equating marginal investment costs with the present value of future production attributable to savings in distribution losses after discounting by interest rates and depreciation.
Reliability of a Variance Estimate Obtained from a Sample Augmented by Multivariate Regression
Authors: Gilroy E. J.
Published: February 2008

A sample of size n1 of a normal random variable y is augmented by n2 regression estimates obtained from p other random variables which, along with y, follow a (p + 1) dimensional normal probability law. The sampling variance of sy2, the estimate of the variance of y obtained from the augmented sample, is derived. The relative reliability of sy2 and sy2 (n1), the variance estimate based on the original n1 observations, is found to depend on n1, n2, p, and R, the multiple correlation between y and the remaining p variables.
Definition and Uses of the Linear Regression Model
Authors: Diskin M. H.
Published: February 2008

A simple three‐element model is proposed as an interpretation of the regression equation for the relationship between annual rainfall and annual runoff from watersheds. The model employs two parameters that are related to the constants used in the regression equation. The parameters of the model can be evaluated by the usual least squares equations if the runoff data do not include zero or near zero values. For arid or semiarid watersheds where runoff may be zero for some years, a special procedure is proposed for evaluating the parameters. The procedure seeks the minimum of an objective function defined as the sum of squared deviations between observed data and prediction lines defined by the regression model.
A Mean Value Theorem in Potential Theory
Authors: Young E. G.
Published: February 2008

Ransford [1970] discusses the flow through a rectangular domain of a conductor with sinks or sources located on the center line between two of the sides that are streamlines, and shows that the mean potential measured transversally varies linearly from one sink or source to the next. This is a particular case of a much more general mean value theorem that is applicable to any distribution of sources and sinks of any shape in the rectangular domain and is not restricted to the small circular sources and sinks located on the center line as required in Ransford's proof by the method of images. The more general theorem may be stated as follows:

For any arrangement of sources and sinks of any shape disposed between straight parallel boundaries which are themselves streamlines, the mean value of the potential function evaluated transversally across the strip at right angles to the parallel boundaries varies linearly between one source or sink and the next.
Numerical Simulation of Flood Wave Modification Due to Bank Storage Effects
Authors: Pinder George F. , Sauer Stanley P.
Published: February 2008

The modification of a flood wave due to bank storage effects can be calculated by using numerical methods. The dynamic equations describing one‐dimensional open channel flow and the equation for two‐dimensional transient groundwater flow are solved simultaneously, coupled by an expression for flow through the wetted perimeter of the channel. Numerical experiments indicate that flood waves may be modified considerably by bank storage, particularly in the lower segments of a long reach, and that the degree of modification is influenced markedly by the hydraulic conductivity of the aquifer.
Nutrients in Streams Draining Woodland and Farmland near Coshocton, Ohio
Authors: Taylor A. W. , Edwards W. M. , Simpson E. C.
Published: February 2008

Nitrogen, phosphate, and potassium concentrations were measured in streams draining woodland and farmland watersheds at Coshocton, Ohio, 1966 through 1969. Temporal variations in the nutrient concentrations were much smaller than the changes in the rate of streamflow. No relationship was found between any nutrient concentration and streamflow, and no seasonal changes in concentration were detected. Nutrient losses from farmland were significantly greater than those from woodland. The nitrate‐N concentration in the farm runoff was below 2 ppm except for one short period when it rose to 10 ppm. The input of nitrogen in the rain was greater than the loss in runoff from both watersheds. The average concentration of phosphate in runoff was 22 ppb (of P) from the farm and 15 ppb from the woodland. The analysis of the data shows that total nutrient losses cannot be calculated meaningfully unless both hydrologic and chemical data are available. The volume of water flow is the most important variable in this calculation.
Porosity and Dispersion Constant Calculations for a Fractured Carbonate Aquifer Using the Two Well Tracer Method
Authors: Grove D. B. , Beetem W. A.
Published: February 2008

A method described in this report uses the time concentration profile from the discharging well of a labeled recharging‐discharging well pair to evaluate an aquifer's porosity and dispersion constant. The technique is applicable for pulse tracer injection and recirculation. Derived equations allow prediction of streamline arc lengths and travel times between wells along streamlines. Adjacent streamlines joining the two wells define crescents that approximate dispersion columns of known length. The summation of breakthrough curve concentration profiles for flow through these individual columns provides a composite breakthrough curve for the entire flow field. Analysis of a tracer test using tritium in a fractured carbonate aquifer near Carlsbad, New Mexico, provided a dispersion constant of 125 feet and a porosity of 12.0%, values consistent with known properties of the aquifer.
Perturbation Solutions of the Dispersion Equation in Porous Mediums
Authors: Dagan Gedeon
Published: February 2008

The solution of the dispersion equation in porous mediums is difficult because of the dependence of the dispersion tensor on the velocity. Approximate solutions of dispersion in nonuniform two‐dimensional flows are sought by perturbation expansions. An inner boundary layer solution for the transition zone between two fluids in steady and unsteady conditions is derived. Two examples of dispersion, radial flow and coastal aquifers, are solved approximately.
Flow through a Tailings Pond Embankment
Authors: Kealy C. Dan , Williams Roy E.
Published: February 2008

Mathematical models that solve the LaPlace or Richards' equation numerically have been used in two ways: to locate the phreatic surface within a mine tailings pond embankment, and to define the subsurface flow system that transports water outward from the pond. Input data needed for the finite element model include the saturated hydraulic conductivity (permeability) distribution within, and beneath, the embankment; the fluid potential values at both upgradient and downgradient boundaries of the embankment; and the geometry and elevation of an approximately impermeable layer at some depth beneath the surface of the embankment.

This technique has been applied to a tailing disposal system in northern Washington. Laboratory tests were used to obtain permeability values from samples collected by the Shelby tube method. Pond boundaries were examined by drillholes and piezometers. Piezometers were also used to validate the configuration of the phreatic surface predicted by the model. Of particular importance to slope stability analysis is the fact that both the model and the check piezometers indicate that a significant portion of the phreatic surface within the embankment is concave upward. Experimentation with the finite element model revealed that the concave upward portion is a consequence of the upstream boundary in a tailings pond being a flow line and embankment permeability being lower near the upstream boundary; the upstream boundary of the flow region in an earth dam is normally an equipotential line.
Energy Exchange and Late Season Snowmelt in a Small Opening in Colorado Subalpine Forest
Authors: Dewalle David R. , Meiman James R.
Published: February 2008

Two‐day melt of a late lying snow patch in a small opening in Colorado subalpine forest was largely due to net radiation and sensible heat exchange. Net radiation supplied 54 and 62% of melt energy on June 19 and 20, 1968, respectively, whereas sensible heat exchange accounted for 49 and 41% of melt energy. Three percent of melt energy was lost by evaporation each day.
A Method for Characterizing the Runoff Potential Rainfall in Water Harvesting Schemes
Authors: Rawitz E. , Hillel D.
Published: February 2008

The ever increasing world demand for water has renewed interest in the development of efficient runoff inducement techniques. Often only scanty hydrologic data are available for planning purposes, and the amount of runoff obtainable can be predicted only on the basis of the prevailing rainfall pattern of a given location. The authors have developed a method for evaluating the runoff producing potential of rainfall patterns and for estimating the amount of water hypothetically obtainable from water harvesting areas of given average infiltration rates. Data obtained from the arid zone of Israel indicate that the distribution of rainfall amounts in relation to rainfall intensities is skewed toward the low intensities and that a few large storms generally account for most of the total rainfall and runoff producing potential. A scaling of rainfall intensity versus relative rainfall amount (fraction of each season's total) shows that seasons with widely different total rainfalls nevertheless have similar relative distribution patterns. This fact suggests the possibility of finding a function that can adequately characterize the relative intensity distribution pattern of a region and can be used to predict runoff potential in relation to seasonal rainfall probabilities.
Regression Analysis of Nonlinear Catchment Systems
Authors: Bidwell V. J.
Published: February 2008

The catchment is considered as a nonlinear system with rainfall input and streamflow output. The system is analyzed by using a discrete form of the nonlinear convolution integrals in conjunction with stepwise multiple regression to obtain a prediction equation from the available rainfall and streamflow records. Experimental results for two rural catchments show that the analytical techniques employed have practical application in the continuous simulation of complex catchment behavior.
Clear‐Cut Logging and Sediment Production in the Oregon Coast Range
Authors: Brown George W. , Krygier James T.
Published: February 2008

The impact of road construction, two patterns of clear‐cut logging, and controlled slash burning on the suspended sediment yield and concentration from three small watersheds in the Oregon Coast Range was studied for 11 years. Sediment production was doubled after road construction but before logging in one watershed and was tripled after burning and clear‐cutting of another watershed. Felling and yarding did not produce statistically significant changes in sediment concentration. Variation in the relation between sediment concentration and water discharge on small undisturbed streams was large. Conclusions about the significance of all but very large changes in sediment concentration are limited because of annual variation for a given watershed, variation between watersheds, and variation with stage at a given point.
Groundwater Flow in a Sandy Tidal Beach: 1. One‐Dimensional Finite Element Analysis
Authors: Harrison W. , Fang C. S. , Wang S. N.
Published: February 2008

A 31‐day time series of observations of beach water table and tidal fluctuations was obtained from 13 wells along a profile perpendicular to the shoreline at Virginia Beach, Virginia. Finite element techniques were applied to solve the one‐dimensional, unsteady state, nonlinear equation for groundwater movement. For the finite element analysis, the semi‐infinite mass (unconfined aquifer) had to be replaced by a finite mass. The boundary conditions were found from the field data by directly solving the flow equation with a finite difference technique. The finite element method, using the variational principle, provided a reasonable solution and afforded economy in computer time. Field data were compared with the corresponding finite element solution. The results indicate the general accuracy of the methodology.
Irrigation planning: 3. The best size irrigation area for a reservoir
Authors: Dudley Norman J. , Musgrave Warren F. , Howell David T.
Published: February 2008

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 elaboration.
Specific conductance model for natural waters and soil solutions of limited salinity levels
Authors: Tanji Kenneth K. , Biggar James W.
Published: February 2008

The specific conductance of waters and soil solutions is estimated with a simplified multicomponent conductance model. This model considers solute composition and concentration and a lumped coefficient for ionic interactions, retardation effects, and ion association. The effect of temperature on specific conductance is also considered. Comparison of measured and calculated specific conductances indicates that this empirical model is most applicable to waters and soil solutions with limited salinity levels. Conductance is shown to be approximately related to the total soluble cations and the total dissolved salts.
Regional analysis of streamflow chemical quality in Texas
Authors: Steele Timothy Doak , Jennings Marshall E.
Published: February 2008

Thirty‐one streamflow water quality stations in Texas, with long‐term historical records ranging from 7 to 28 years, were selected for statistical analyses of the annual mean concentrations of the major chemical constituents. A statewide multiple regression analysis using frequency characteristics of annual mean water quality constituents as dependent variables and selected basin characteristics as independent variables was investigated as a means of regionalizing information on annual water quality characteristics. For the two different regression models investigated, a single independent variable, generally stream discharge or average basin rainfall, explained a significant part of the variance of the dependent water quality variables. Areal analysis of residuals of the statewide regression models indicated two distinct regional patterns. Correlation coefficients for the concentration‐rainfall regional models ranged from 0.80 to 0.97 and the standard errors of estimate were between 26 and 99% of the means of the dependent variables. An analysis of various concentration‐conductance relationships for the statewide data also gave favorable results, and provided an alternate method for obtaining estimates of streamflow chemical quality characteristics.
Digital computer simulation for solving management problems of conjunctive groundwater and surface water systems
Authors: Young Robert A. , Bredehoeft John D.
Published: February 2008

In river basins where aquifers are intimately associated with streams, the unrestricted development of groundwater can reduce streamflows and hence jeopardize the rights to the flow of surface water. A simulation model to aid in the solution of such problems was developed. The model is composed of (1) a hydrologic model that represents the physical response of the stream‐aquifer system to changes in river flows, diversions, and pumping and treats streamflow as a stochastic input and (2) an economic model that represents the response of irrigation water users to variations in water supply and cost. These elements were incorporated into a decision framework so that the net income to the water resource system associated with alternative management schemes could be measured. The results of operating the model with parameters representing conditions in the South Platte Valley of eastern Colorado under alternative institutional and hydrologic conditions are reported.
Small sample estimation of ρ1
Authors: Wallis James R. , O'Connell P. Enda
Published: February 2008

Hydrologists frequently need to estimate lag 1 correlation ρ1 from rather short observed records of length n. The most commonly used algorithms for estimating ρ1 can give seriously biased estimates if n is small and |ρ1| is large. Small sample bias corrections based on the assumption of a lag 1 Markov generating process are available for
, but the corrected estimates tend to have larger variance than the uncorrected estimates do.
Solution of transient groundwater flow problems by the finite element method
Authors: Verruijt A.
Published: February 2008

The derivation of the basic equations of a finite element method for transient groundwater flow problems is simplified when the approximation of the time derivative by a finite difference equation is made before the introduction of the variational principle. Existing programs for steady state problems can easily be extended to the transient case in this way, and a stable numerical procedure can be obtained.
River Dee Research Program: 1. Operating multipurpose reservoir systems for water supply and flood alleviation
Authors: Jamieson D. G.
Published: February 2008

Two common purposes for which multipurpose reservoirs are operated are water supply and flood alleviation. Apportioning the available reservoir storage between these interests requires a compromise since their storage requirements are in direct conflict. The lack of a suitable basis for optimizing this apportionment has led to the use of a ‘satisficing’ model in which priority has been given to water supply: rules were then developed to optimize the operation of the reservoirs with respect to the secondary purpose, flood alleviation, provided the primary purpose is fulfilled to a predetermined standard. The resulting control policy is being applied to the River Dee system in Wales, which comprises two multipurpose reservoirs and one direct supply reservoir.
Rain gage catch variation due to airflow disturbances around a standard rain gage
Authors: Mueller Charles C. , Kidder Ernest H.
Published: February 2008

Although the spatial position has an important influence on the performance of a rain gage, the physical presence of the gage itself must be considered a hindrance to its operation. An obstruction to airflow in the vicinity of the gage, owing to the presence of the gage, results in disturbances in the local precipitation pattern in which the rainfall measurement is made. The airflow pattern data obtained in a study of a wind tunnel model and aerodynamic drag characteristics of water drops are used to perform a computer simulation on the movements of the drops as they approach the gage. These drop paths are analyzed to establish the effectiveness of the gage in measuring precipitation. If we use drop sizes of 1–5 mm in diameter, we find that the gage catches from 103 to 11% of the drops as the free stream velocity increases from 10 to 50 feet per second. In general, the decrease in catch is less pronounced as the drop size is increased.
Line source distributions in two dimensions: Applications to water quality
Authors: Di Toro Dominic M.
Published: February 2008

The concentration distribution resulting from a uniform line source of mass that decays following first order kinetics in a two‐dimensional dispersive field is obtained. The resulting solution is given in terms of a tabulated function, and a typical water quality example is provided.
Developing simulation models
Authors: James William
Published: February 2008

Simulation models are commonly resolved in time and space beyond the integrity of available field observations. Input data are fudged accordingly, and, ultimately, expensive simulation models coexist with inadequate data bases. Such manipulation is necessary in sensitivity analysis, but a compromise between data collection and model extrapolation must be found. The rationale for the systematic development of a simulation model and the concomitant data collection program is presented in this paper and should be useful for managing difficult simulation studies.
KSIM: A methodology for interactive resource policy simulation
Authors: Kane Julius , Vertinsky Ilan , Thomson William
Published: February 2008

A new mathematical language (KSIM) has been developed and designed for interactive team use. Many features of KSIM make it particularly appropriate for use in formulating environmental policy. (1) It is easily grasped by the nonmathematical specialist and can communicate the workings of complex, nonlinear feedback systems to such people. (2) It allows for ready entry of such ‘soft’ subjective variables as environmental quality and national sovereignty. (3) It emphasizes the significance of structural relations rather than numerical prediction. (4) It is flexible and easily generalized. As an illustration of its use, we show how KSIM can facilitate discussion of the multiple impacts of possible Canadian water sales to the United States.
Effects of air pressure on water flow in an unsaturated stratified vertical column of sand
Authors: Vachaud G. , Vauclin M. , Khanji D. , Wakil M.
Published: February 2008

By the use of a vertical stratified column of unsaturated soil the effects of air pressure on constant flux infiltration and gravity drainage were studied experimentally. Water content was measured by γ ray attenuation; water pressures were obtained simultaneously at 10 different levels in the column by using tensiometers connected to pressure transducers. In addition, the differential ports of some transducers were connected by a ‘scanivalve’ either to the external atmosphere or to the soil air phase by using hypodermic needles inserted through the column wall. The soil column consisted of three layers: fine sand over coarse sand over fine sand. The wall of the column was also provided with a series of adjustable air ports to allow experiments either with or without lateral air movement. It was shown that (1) the local soil air pressure can differ significantly from the external atmospheric pressure, e.g., +50 mb for rain with an intensity of 3 cm/hr or −15 mb for gravity drainage, and (2) the water flow depends not only on the boundary conditions in terms of water content and/or water pressure but also on the air pressure conditions. We conclude that the air pressure must be taken into account in determining the soil water suction, and we suggest that the flow equations must be written in terms of two‐phase immiscible fluid flow.
Storm flow from hardwood‐forested and cleared watersheds in New Hampshire
Authors: Hornbeck James W.
Published: February 2008

Changes in storm flow as a result of forest clearing by cutting of trees and subsequent applications of herbicides were determined for a small mountainous watershed in New Hampshire by using a paired watershed as a control. Reduction of transpiration and interception losses produced wetter soils with less opportunity for storing rainfall. Consequently, quick flow volumes and instantaneous peaks were nearly always increased during the growing season. The absence of the hardwood forest canopy also caused earlier and more rapid snowmelt and affected most spring storm flow events involving snow water. In contrast, storm events occurring after soil moisture recharge in the fall and before the start of spring snowmelt were unaffected by forest clearing. Although the spring and summer storm flow changes were readily detectable, their magnitude was not great. The maximum increase in individual quick flow was 30 mm for the summer streamflow season and just over 50 mm during spring snowmelt. Mean quick flow changes were much lower. The relatively small amount of forest clearing currently taking place in New England headwaters should not increase downstream flood potential.
Fate of suspended sediment during basin recharge
Authors: Goss D. W. , Smith S. J. , Stewart B. A. , Jones O. R.
Published: February 2008

Suspended sediment in water used for recharge was tagged with the radioisotope 134Cs to determine the extent of its movement into materials underlying recharge basins and to aid in evaluating the effect of its accumulation on infiltration rates and the basin life. When openings of naturally occurring large pores were allowed to remain at the basin surface, 50% of the sediment suspended in the recharge water was moved deeper than 18 inches. However, when large‐pore openings at the surface were destroyed by cultivation, over 90% of the suspended sediment was filtered in the upper 1 inch. Most of this sediment could easily be removed at frequent intervals. The suspended sediment that moved deeper than about 0.15 inch, the depth removed at the end of each recharge cycle, has not noticeably reduced infiltration rates of a 0.1‐acre experimental basin.
Accumulation of fallout cesium 137 in soils and sediments in selected watersheds
Authors: McHenry J. Roger , Ritchie Jerry C. , Gill Angela C.
Published: February 2008

The fallout of certain radioisotopes produced in nuclear explosions and their subsequent dispersion over the earth provide tracers for following the movement of soil particles in the sedimentation cycle. Cesium 137, which is strongly adsorbed by most soil particles, was identified in sampled soils and sediments by gamma differential spectrometric analysis using a 1024‐channel pulse height analyzer ancl a 10‐ × 12.5‐cm NaI (thallium) scintillation crystal detector. The concentration of 137Cs measured ranged from 0.01 to 3.28 pci/g in soils and from 0.01 to 10.05 pci/g in sediments. Uranium, thorium, and potassium were determined simultaneously with 137Cs. Total potassium ranged from a trace to 5.4%, uranium from 0.5 to 9.4 ppm, and thorium from 1.9 to 42.0 ppm. The concentration of 137Cs in reservoir sediments varied with depth. In some reservoirs the years of greatest 137Cs fallout were correlated with layers containing peak concentrations of 137Cs in the sediment profile. The occurrence of 137Cs in sediments was significantly correlated with the amount of clay and of organic matter present. The amount of 137Cs was greater per unit area in sampled sediments than in the contributing watersheds, and the relative concentration factor was as large as 24. This accumulation of 137Cs in reservoir sediments is indicative of the pollution possible in reservoirs as a result of fallout within the watershed but not necessarily within the reservoir.
Dew: An addition to the hydrologic balance of Douglas fir
Authors: Fritschen Leo J. , Doraiswamy Paul
Published: February 2008

The hydrologic balance of a 28‐meter Douglas fir tree in a weighing lysimeter was determined for 2 clear days in May 1972. The results indicated dew accumulations of 6.4 and 10.9 liters, which represent 15 and 20% of 42.5 and 55.2 liters of evaporation from the tree. Since the dew was recorded as a weight increase, its source has to be the atmosphere. In the Pacific Northwest, conditions are favorable for dew formation during most of the summer and fall. Thus dew formation could represent a large part of the hydrologic balance of fir forests.
Price elasticity of demand for municipal water: A case study of Tucson, Arizona
Authors: Young Robert A.
Published: February 2008

Estimates of the price elasticity of demand (the proportional response of consumption to price change) for municipal water in Tucson, Arizona, were derived by statistical regression procedures. A significant shift in demand was found to have occurred subsequent to 1964. The price elasticity was estimated at about −0.63 during 1946–1964 and −0.41 during 1965–1971. These results are consistent with those obtained in other studies of urban water demand in the arid parts of the western United States. The data subjected to statistical analysis were annual observations of consumption, price, and other factors for one community in contrast to the more typical approach using cross‐sectional observations of a number of communities during a specific time period.
Modeling the Regulation of Lake Superior Under Uncertainty of Future Water Supplies
Authors: Su Shiaw Yuan , Deininger Rolf A.
Published: February 2008

This paper considers the regulation of the water levels of Lake Superior, which can be controlled at its outlet. The inflows to the lake were treated as stochastic random variables, and the objective was to find operating policies that minimized the expected undiscounted yearly losses over an infinite time horizon. The system was modeled as a periodic Markovian decision problem. A new algorithm based on White's method of successive approximations for solving single chained and completely ergodic Markovian decision problems was developed and was proven to be fairly efficient in terms of computer storage and computation time. Transition probabilities of the inflows were estimated from 64 years of data. The economic loss functions used in the model considered the losses due to navigation inconvenience and shore property damage. An extensive sensitivity analysis was conducted to determine their influence on the optimal operating policies. To show the validity of the model, the newly developed policies were tested against the current operating policy by using the historical inflow record as data. The results show that if some of the developed operating policies were adopted, the average yearly losses could be reduced by at least 15%. At the same time the monthly lake level variances could be reduced by 25%.