bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting and Mapping the Average Hydrologic Response for the Eastern United States
Authors: Woodruff James F. , Hewlett John D.
Published: February 2008

An attempt was made to predict the average annual hydrologic response (ratio of annual direct runoff to annual precipitation) of ungaged watersheds in the East by regression against 15 planimetric, hypsometric, and land use factors available on 90 selected test basins (2 to 100 square miles) from New York to Alabama. The regression coefficients were nonsignificant indicating that the average percentage of a basin's annual precipitation that will become quick flow cannot be predicted from available basin morphometry and implying that response is controlled chiefly by porous mantle factors not measurable on normal data sources. A hydrologic response map of the eastern United States based on an expanded set of 201 basins up to 200 square miles revealed specific regions of high flood producing potential clearly related to geologic provinces. It is suggested that hydrologic response is a meaningful parameter that may be best derived by measuring precipitation and streamflow by cheap, short‐term methods traditionally rejected as uneconomical.
Nonuniqueness of Steady State Fingering Solutions in Porous Media
Authors: Varnon James E. , Greenkorn Robert A.
Published: February 2008

Steady state solutions for single viscous fingers are nonunique because the position of the interfacial boundary is not specified. Expanding the steady state problem to include an arbitrary number of fingers does not make the solution unique. The initial value problem however does have a unique solution, which suggests that it is futile to look for additional conservation type equations in the hope of making the steady state solutions unique.
Reorientation of Our Saline Water Resources Thinking
Authors: Kohout F. A.
Published: February 2008

Desalination as a method for making sweet water from salt water is currently one of the most important factors that conceptually change the direction of our investigation of the nation's water resources. Desalting costs have decreased from about $5 per 1000 gallons 10 years ago to about $1 per 1000 gallons for seawater distillation today. For membrane desalting of brackish ground water, costs now range from 40 cents to $1 per 1000 gallons. Projected costs for desalting in the mid‐1970's are in the range of from 25 to 50 cents per 1000 gallons at the plant, which is in the same range as consumer costs for delivered water in large cities in 1969. Thus, saline ground water has developed considerable intrinsic worth. In addition, the pore space occupied by the saline water can be considered as a useful medium for storing natural gas, for artificial recharge and recovery of freshwater stored as ‘bubbles’, or for storing certain toxic industrial wastes. These beneficial uses are not necessarily competitive or incompatible, but great reliance must be placed on hydrologic prediction if haphazard interference of the various uses is to be avoided. Our thinking, planning, and investigative funding must be greatly expanded to provide necessary data on the physical, chemical, and hydrologic boundaries of saline water systems. On this total view of the environment depend enlightened engineering and legal decisions concerning best use of saline ground water and saline aquifers.
Quantitative Mapping of Salinity, Volume, and Yield of Saline Aquifers Using Borehole Geophysical Logs
Authors: Turcan A. N. , Winslow A. G.
Published: February 2008

Techniques that permit a quick, practical, and satisfactory evaluation of electrical logs were developed to estimate the volume and distribution of saline water in aquifers in Louisiana. Of about 200,000 available electrical and induction‐electrical logs, approximately 1000 representative logs (about 1 per township) were selected for detailed analysis. An empirical relation, called the field formation resistivity factor Ff, was determined as the ratio of formation resistivity R0 to water resistivity Rw corrected to a temperature of 25°C, Ff = R0/Rw. The field formation resistivity factor was used to estimate the altitude of groundwater salinity interfaces of 1,000, 3,000, and 10,000 mg/l (milligrams per liter) of dissolved solids. Average coefficients of permeability values and bed thickness information were used to determine coefficients of transmissibility. Using theoretical and standard conditions of well design, yield, and aquifer thickness, well yields were computed. This permitted an areal comparison of yield from each of the saline water zones.
Comparative Cost Evaluation of Desalted Water Supply versus Alternative Freshwater Supply from a Conventional Source
Authors: Morris Donald E.
Published: February 2008

A costing procedure was developed in the desalt studies made in Texas so that calculations of the cost of water supply produced by saline water conversion could be compared to the cost of providing an alternative freshwater supply from a conventional source. In studies made by the Texas Water Development Board, the cost of desalted water is generally higher than the cost of water from alternative sources. For desalting, the elements included in the costing procedure were: well fields for saline feedwater supply; intake system and pumping station; pipelines; pretreatment for saline water; the desalting plant ; and brine disposal. For a conventional water supply system the elements of cost included were raw water cost; well field or intake system; pipeline and required pumping stations; and a conventional water treatment plant. The final economic justification of a desalt project may include such factors as chemical quality comparisons, secondary benefits, and project life comparison to future availability of alternative supply. The Texas Water Development Board considers that desalting is a very practical solution to the interim water supply problems that exist in many areas of the state.
Application of Industrial Dynamics Concepts to Decision Making in Environmental Management
Authors: Gates W. E. , Males R. M. , Walker J. F.
Published: February 2008

Dynamic feedback modeling of the decision making processes of a California regional water quality board was carried out to study the interactions of the board with various groups having different vested interests in water quality and the impact of these interactions on achieved water quality. It is concluded that such models are useful for exploring the implications of alternative institutional arrangements, and some tentative recommendations are stated.
A General Numerical Solution of the Two‐Dimensional Diffusion‐Convection Equation by the Finite Element Method
Authors: Guymon G. L. , Scott V. H. , Herrmann L. R.
Published: February 2008

The two‐dimensional diffusion‐convection equation, together with the appropriate auxiliary conditions, is used to describe approximately the motion of dissolved constituents in porous media flow, dispersion of pollutants in streams and estuaries, energy transfer in reservoirs, and other natural transport processes. The two‐dimensional diffusion‐convection equation, with an assumed set of auxiliary conditions, is converted to a variational principle for systems that do not involve mixed partials. The variational principle is in turn solved by the Ritz procedure by dividing the domain of interest into an arbitrary number of finite triangular elements. Within each element the unknown function states are represented by a first order space polynomial. The resulting system of first order linear equations is then solved by numerical differentiation using the Adams‐Moulton multistep predictor‐corrector method.
Statistical Decision Theory Techniques for the Revision of Mean Flood Flow Regression Estimates
Authors: Shane Richard M. , Gaver Donald P.
Published: February 2008

Two statistical estimating procedures are presented for using regression information along with direct observations to obtain estimates of the expected value of peak flood discharge rates exceeding a constant base. The first type of estimate represents the minimum mean squared error linear combination of regression and direct estimates, whereas the second is a Bayesian estimate based on an objective prior distribution associated with the regression model. A comparison of combined estimates to regression and direct estimates used alone indicates that a significant reduction in the mean squared error is obtained by using combined estimates. A comparison of the two methods for obtaining a combined estimate indicates that in many cases they both give essentially the same result.
Shading Inverted Pyranometers and Measurements of Radiation Reflected from an Alfalfa Crop
Authors: Brown K. W. , Rosenberg Norman J. , Doraiswamy P. C.
Published: February 2008

Field experiments were made to determine if pyranometers require shading when inverted to measure reflected radiation, and if the view angle of such instruments may be restricted to allow for measurement over small plots. Results indicate that shade must be provided for inverted Eppley pyranometers to prevent radiation from entering the glass bulb above the plane of the sensor. It does not appear necessary to shade the entire bulb. Reflection from a well‐developed alfalfa crop was found anisotropic, indicating that shades which reduce the view angle significantly should not be used.
A Comparative Study of Critical Drought Simulation
Authors: Askew A. J. , Yeh W. W‐G. , Hall W. A.
Published: February 2008

A set of monthly streamflow records is generated and analyzed to give a set of synthetic critical periods. Some characteristics of these periods are derived, and the mean and standard deviation of their values are compared with the appropriate values for the historical critical period. This procedure is repeated with three characteristics for a number of different rivers by using a variety of generating techniques. A study of the results allows a comparison between the generating techniques in regard to both their cost in computer time and their ability to synthesize critical droughts comparable to those recorded historically. The results appear to be influenced by the relative aridity of the watershed and by the size of the reservoir considered. In addition, some general conclusions can be drawn regarding the advisability of using generated streamflow in studies of reservoir design and operation.
Increases in Streamflow after Converting Chaparral to Grass
Authors: Hibbert Alden R.
Published: February 2008

Water yield has increased substantially on two small chaparral watersheds in central Arizona following brush control and conversion to grass. Winter precipitation is the major source of water yield. Summer rains begin in July and normally account for about one‐fourth of the annual precipitation but generally have little effect on streamflow. When annual precipitation is less than 16 inches, increase in water yield resulting from treatment is likely to be less than 2 inches. However, the efficiency of the conversion for producing extra water improves with rainfall, at least up to 34 inches. At this amount of annual precipitation, the increase in flow may reach 12 inches or more, depending on seasonal distribution of the rain.
Flood Risk and Agricultural Land Values: A Test
Authors: Struyk Raymond J.
Published: February 2008

The study investigates the usefulness of land values to measure the capitalized damages to agricultural land resulting from flooding by using a multiple linear regression technique to control for nonflood factors affecting land values. The model is applied to a study area on the Missouri River by using appraisal data on the value of land and improvements. Significant differentials in land values between two flood‐free areas and a flood‐prone area attributable to flood risk are individually established. Comparison of the results with other measures of flood risk shows the results to be reliable.
Reforestation Influences on Small Watershed Streamflow
Authors: McGuinness J. L. , Harrold L. L.
Published: February 2008

Analysis of flow duration curves showed that reforestation of a 44‐acre watershed near Coshocton, Ohio, reduced flow in the low flow tail of the curve but did not significantly reduce flows above 0.25 inch per day. Other analyses showed that reductions also occurred in the maximum annual flow volumes for all periods of flow durations of 1 day or longer. The onset of dormant season flow was significantly delayed.
Irrigation Planning 2: Choosing Optimal Acreages within a Season
Authors: Dudley Norman J. , Howell David T. , Musgrave Warren F.
Published: February 2008

Three problems involved in planning and operating an irrigation system are (1) the short‐run problem of allocating a quantity of water in time over an irrigation season, (2) the intermediate‐run problem of deciding what area of crop to plant at the beginning of an irrigation season, and (3) the long‐run problem of deciding what area of land to develop for irrigation. This paper concerns the intermediate‐run problem. Crop growth is simulated with a simple crop growth model over a number of years on a large acreage supplied with water from a reservoir subject to stochastic inflows; the demand for water by the crop also being stochastic. Irrigation decision rules at each of a number of decision points in time are taken from the output of a simulation‐dynamic programing model used to solve the short‐run problem. The approach used allows for the abandonment for the rest of the season of portions of the area initially irrigated but does not allow for temporary abandonment, and reinstatement during the season, which is a limitation. The results show the best irrigated acreage to plant to be an approximately linear function of the reservoir contents at the beginning of the season. The function is found to be highly sensitive to changes in the profitability of the best dryland alternative enterprise. The cost of planting suboptimal acreages is found to be high.
Oscillatory Kernel Functions in Linear Hydrologic Models
Authors: Blank D. , Delleur J. W. , Giorgini Aldo
Published: February 2008

The rainfall‐runoff relation was expressed by the convolution integral. The kernel function was evaluated by the Fourier and Laplace gamma transforms and by the direct method. Three analytical examples (known kernels) were analyzed and used to compare the effectiveness of these methods. The Fourier transform method was used for field data. The results indicated that for a third of the storms oscillatory kernels were obtained. Oscillations were not necessarily due to nonlinearities but could arise from random noise in the data. Low‐pass digital filtering of input (excess rainfall) and output (direct runoff) eliminated the kernel oscillations in most cases. The cutoff frequency was approximately the sampling frequency. Accurate output reproduction was obtained by convolution of the original kernel, the smoothed kernel, or the kernel resulting from the filtered data.
Runoff Processes during Snowmelt
Authors: Dunne Thomas , Black Richard D.
Published: February 2008

During the snowmelt period of 1967, snowmelt runoff from three pastured plots was measured as it moved to the stream channel over the ground surface, through the topsoil, and through the phreatic zone. Because of the presence of a thin layer of concrete frost in the normally porous topsoil, the infiltration capacity of the soil was reduced to a very low value. Almost one half of the meltwater left the plots as overland flow. Discharge rates, total volumes, and timing of this portion of the runoff were strongly controlled by incoming shortwave radiation. The response of subsurface flow to melting was heavily damped by storage and transmission of water in the soil. Combined daily hydrographs of runoff were dominated by overland flow. Comparison of the timing of such hydrographs with concurrent stream channel hydrographs from basins of the Sleepers River Experimental Watershed suggests that overland flow was a major control of the diurnal fluctuations of streamflow. Previous studies in the same area have demonstrated that much of the overland flow contributing to the responsive stream hydrographs of these basins originates on saturated areas of the watershed.
Simultaneous Solute and Water Transfer for an Unsaturated Soil
Authors: Warrick A. W. , Biggar J. W. , Nielsen D. R.
Published: February 2008

The simultaneous transfer of solute and water during infiltration was studied both in the field and numerically. An apparent diffusion coefficient of about 0.07 cm2/min provided maximum solute concentration values agreeable with field data over a 17‐hour period. The advance of a solute front introduced as irrigation water is shown to be nearly independent of the initial soil moisture content but highly dependent on the moisture content maintained at the soil surface during infiltration.
An Automatic Solution for the Inverse Problem
Authors: Emsellem Y. , De Marsily G.
Published: February 2008

The automatic computing of the estimated hydraulic parameters of an aquifer when the data consist of the piezometric head and the flow rates of the wells (the ‘inverse problem’) is a very good example of an improperly posed problem, if we try to solve only its mathematical part. Yet if we use the available physical information about the structure of the desired solution, the problem becomes properly posed mathematically. The main idea is that the desired solution is the regional distribution of the hydraulic parameters and is consequently the softest mathematical solution. Nevertheless, as the mathematical problem improves, we need a practical way to obtain the best estimate of the hydraulic parameters from actual measures, which always include errors. The new method gives a solution to these two problems. Because of the complexity of the theoretical aspects of the method, the present paper is only an abstract.
Computer‐Aided Conflict Resolution in Water Resource Planning: An Illustration
Authors: Flack J. Ernest , Summers David A.
Published: February 2008

Water resource planning is an increasingly complex process subject to conflicting judgments about the ‘best’ plan for implementation. Conflict analysis that uses an interactive computer graphics system holds promise of helping decision makers resolve the judgmental differences that arise in the planning process. The system illustrated herein, called Cognograph, is used to make explicit to water planners their sources of agreement and disagreement and to aid them in resolving their differences.
A Statistical Method for Flow Prediction, River Murray Example
Authors: Veitch L. G. , Shepherd K. J.
Published: February 2008

Use of multiple linear regression enabled prediction equations to be obtained for the flow of water leaving the River Murray in the Edward River 1‐12 days forward. The predictors, being flow readings at appropriate stations taken over the previous 5 days, are highly correlated and subject to error, so a direct application of regression may give unreliable results. Therefore the correlations between the predictors were investigated by principal component analyses to overcome these difficulties. A reduced number of new variates, approximating the principal components, were used that retained the relevant information, were nearly uncorrelated, and gave interpolation in time. The regression equations were tested for both heterogeneity and stability. The results indicate a fairly reliable forecasting scheme, but suggest that it should be updated at periodic intervals.
A Classification Channel Links in Stream Networks
Authors: Mock Steven J.
Published: February 2008

Differences in the length properties and occurrence frequencies among types of channel links occur in natural stream networks. We define six types of channel links: (1) S (source) links, (2) TS (tributary source) links, (3) B (bifurcating) links, (4) TB (tributary bifurcating) links, (5) CT (cis‐trans) links, and (6) T (tributary) links. The topologically random model of channel networks provides the basis for a series of equations defining the probability of occurrence of each link type in a topologically random population of networks of any specified magnitude. Examination of interior link lengths from 12 stream networks supports the hypothesis that the interior link types defined here differ in their length properties.
A Finite Difference Method for Unsteady Flow in Variably Saturated Porous Media: Application to a Single Pumping Well
Authors: Cooley Richard L.
Published: February 2008

Finite difference equations were derived by using the divergence theorem to convert the nonlinear partial differential equation (which approximately describes liquid flow in a variably saturated, elastic porous medium) to an integral equation, and then to integrate around individual mesh volume elements. Original nonlinearity of the differential equation was preserved by keeping saturations and relative conductivities current with hydraulic heads during the iterative matrix solution method. The problem of axisymmetric flow to a water well that penetrates one or more elastic rock units, the upper one of which is unconfmed, provides a convenient vehicle for analysis of the procedural and theoretical study of unconfined and semiconfined flow. Of the three methods tried to solve the matrix equation that resulted from the finite difference equations (which included a form of the direct alternating direction implicit method, the iterative alternating direction implicit method, and the line successive overrelaxation method), the line successive overrelaxation method was the fastest and was selected for use in a general computer program. A comparison with analytical solutions that use Boulton's convolution integral as a velocity boundary condition at the water table for a single aquifer and an aquifer‐aquitard system demonstrates close correspondence of the numerical and analytical solutions, even for a case where the water table is lowered appreciably.
Effect of water availability on manufacturing employment in the Tennessee Valley Region
Authors: Garrison Charles B. , Paulson Albert S.
Published: February 2008

The study indicates a significant microlocation relationship between water‐oriented manufacturing employment and water availability, where water availability is measured in terms of 7‐day, 10‐year minimum streamflow, in the 194‐county Tennessee Valley region. At the county level, chi square tests of independence indicate that concentrations of at least 500 employees in water‐oriented manufacturing (and increases of at least 250 over the period 1959–1968) are significantly related to water availability. Further, the data and tests suggest that a streamflow in the neighborhood of 400 cfs (cubic feet per second) is the critical or threshold flow necessary for the occurrence of such employment concentrations. To explain the variation in employment per river mile among small regions within the region, a regression equation with population density as the independent variable was constructed. The regression indicates that, for a difference of 10% in population density between small regions, employment per river mile varies by 8.15%.
Multilag multivariate autoregressive model for the generation of operational hydrology
Authors: Pegram G. G. S. , James W.
Published: February 2008

The multivariate model previously described by N. C. Matalas is extended to the multilag case.
Public opinion and knowledge concerning new water sources in California
Authors: Bruvold William H.
Published: February 2008

Public opinion in California regarding water supply augmentation, preference for new sources of water, and the basis for this preference was assessed along with knowledge of new sources. Data were obtained by a survey of 100 respondents from each of 10 selected communities. The results indicated that most respondents were not convinced that water supply augmentation was needed, that knowledge of new sources was incomplete, and that imported surface water and desalinized water were the first preferences for new supply primarily because of perceived abundance.
Dynamic programing of capacity expansion of municipal water treatment system
Authors: Hinomoto Hirohide
Published: February 2008

The multistage capacity expansion of a municipal water treatment system is investigated to determine the sizes of new treatment plants and the times at which these new plants are added to the system. The capital and operating costs of these plants are given by concave functions reflecting economies of scale available with an increase in capacity. To determine the optimum sizes and installation times of the new plants, this expansion problem is formulated as a dynamic programing model.
New measure of the topologic structure of dendritic drainage networks
Authors: Jarvis Richard S.
Published: February 2008

A new measure of network topologic structure, the E index, is developed and applied. The index is shown to be a practical refinement of Smart's ambilateral classes and is tested on Strahler third and fourth order networks drawn from two regions. By means of interregional comparisons and intraregional tests on networks of permanent channel flow and valley pattern, the E index is shown to be capable of interpretation in terms of network growth processes at least as an indicator for further research incorporating metric elements.
Note on charges and bribes in the long run within watersheds
Authors: Maxwell Lynn C.
Published: February 2008

The impact of charges and bribes on the long run price, output, and waste emission levels of firms and industries located in different watersheds is analyzed. The analysis concludes that the impact of charges or bribes on long run waste emission levels of firms within any one watershed is indeterminate because of possible scale adjustments of firms due to changes in resource prices. For example, a charge that encourages the exit of firms from an increasing cost industry can lead to increased waste emissions from any one firm and watershed if the prices of resources associated with plant scale decline in relation to the prices of other resources.
Combined use of optimization and simulation models in river basin planning
Authors: Jacoby Henry D. , Loucks Daniel P.
Published: February 2008

Simulation models have proved extremely useful as an aid to river basin planning. All suffer a common difficulty, however, since the analyst himself must formulate the physical design to be studied in each computer run. If the basin is large and offers a variety of development opportunities, the number of alternative system plans from which he must choose can be extremely large. This paper reports on an investigation of the use of analytical optimization models to ‘screen’ the set of possible plans and to select a small number worthy of simulation analysis. The Delaware River basin being used as an example, deterministic and stochastic optimizing models have been developed and applied to both static and dynamic (multiperiod) planning problems. The resulting designs have been analyzed by using a large‐scale digital simulation model of the basin so that the ability of the screening models to identify high‐valued alternatives can be evaluated. In this context the results indicate considerable promise for the combined use of optimization and simulation models.
Transient analysis of the Detroit River by the implicit method
Authors: Quinn Frank H. , Wylie E. Benjamin
Published: February 2008

A hydraulic transient model of the Detroit River is developed by using the implicit method to solve the complete equations of continuity and motion. The river is modeled in the shape of a Y and has one main channel and two branching channels. The stability of the numerical solution, which uses the Newton‐Raphson algorithm, is found to be dependent on the selection of a weighting coefficient. This coefficient determines the position at which the equations are evaluated on the X‐t grid. The model inputs consist of water surface hydrographs at the head and mouth of the river. The outputs consist of flows at each end of the three channels and water surface elevations at the junction of the Y. Transient flows of the Detroit River induced by a severe wind tide on Lake Erie were simulated to illustrate the model. Good agreement was obtained between measured and computed water surface elevations at the junction of the Y.
Locomotor response of goldfish, channel catfish, and largemouth bass to a ‘copper‐polluted’ mass of water in an open field
Authors: Timms A. M. , Kleerekoper H. , Matis J.
Published: February 2008

The locomotor response of goldfish, largemouth bass, and channel catfish to ‘copper‐polluted’ water at a maximum concentration of 50 μg/l Cu++ in an open field, free choice situation was monitored. The rate of water flow was 1.8 cm/sec. The largemouth bass were unaffected, but the goldfish and the channel catfish tended to orient themselves toward the source of the ion. The degree of this orientation was less, however, than that found in shallower gradients of the same copper concentration as described by Kleerekoper et al. in 1972. When goldfish were exposed to the copper ion in a uniform field so that neither avoidance of nor attraction to the polluted mass was possible, no change in orientation was observed. It is concluded that the slope of the copper gradient between ‘clean’ and ‘polluted’ water rather than the eventual highest concentration of the ion (50 μg/1) affected the orientation and the locomotor behavior of the catfish and the goldfish.
Estimating salinity of streams in the southwestern United States
Authors: Pionke H. B. , Nicks A. D. , Schoof R. R.
Published: February 2008

A model is presented for the improved estimation of stream salinity as a function of streamflow components. The proposed model ln s = K − a ln Qb − b Qs/Qb was constructed by using base flow Qb and the ratio of surface to base flow Qs/Qb, all expressed as daily values averaged for each month. The coefficients a and b and the constant K are derived by regression. Among individual parameters tested, the ratio Qs/Qb was the best salinity predictor for ephemeral streams. Conversely, total flow was the best individual predictor for the stream draining the largest watershed. Stream salinity was estimated by three models: one based on total flow, one developed by Ledbetter and Gloyna, and the model proposed above. The models were evaluated statistically by using data from five streams in Kansas, Oklahoma, and New Mexico. The proposed model explained 77.1–95.2% of the variability in stream salinity and never exceeded a 30% error for any stream as determined from the standard error of estimate. It was found to estimate more precisely and accurately the salinity of streams characterized by ephemeral flows than the other models did, and was approximately equivalent to the Ledbetter‐Gloyna equation in estimating the salinity of larger streams characterized by more stable flows.
Three‐dimensional heated surface jets
Authors: Stolzenbach K. D. , Harleman D. R. F.
Published: February 2008

A theory for the three‐dimensional temperature and velocity distribution in a heated water discharge issuing from a rectangular channel at the water surface is developed by considering the effects of lateral gravitational spreading, reduction of vertical entrainment, and surface heat loss on a free turbulent jet. The behavior of such a heated jet depends primarily on the initial densimetric Froude number and to a lesser extent on the depth‐width ratio of the discharge channel. The gravitational stability of the jet and the angle of lateral spread increase away from the discharge point, whereas the vertical entrainment decreases. Heat loss through the water surface is significant only far from the discharge point, where the jet is plumelike rather than jetlike. The theoretical results are verified by experimental evidence.
Mass transport in flowing groundwater
Authors: Bredehoeft John D. , Pinder George F.
Published: February 2008

The mass transport equation and the equation of motion have been coupled and solved numerically for a saturated isothermal groundwater system in which there are no chemical reactions. A case history of groundwater contamination at Brunswick, Georgia, illustrates the use of this physical‐chemical model in predicting and controlling the future movement of contaminants.
Effect of nonlinear stabilizing salinity profiles on thermal convection in a porous medium layer
Authors: Rubin Hillel
Published: February 2008

Nonlinear salinity profiles may exist in an aquifer when salt water and freshwater are brought into contact. They may be maintained indefinitely by a horizontal flow. The effect of such salinity profiles on marginal stability and overstability, as well as on thermal convection, was investigated. Nonlinearity of the salinity profile was found to affect the stability criteria of the field and to change the shape of the convective cells appearing at instability.
Optimal path of interregional investment and allocation of water
Authors: Regev Uri , Schwartz Aba
Published: February 2008

The problem of simultaneous optimization of investment in and allocation of water is investigated. A discrete time control theory is applied to formalize the model in which the interaction of regional and seasonal considerations plays the crucial role. Economic interpretation of the optimal conditions reveals the following price policy implications: Prices at two adjacent regions should differ by (at most) the cost of transportation. The general trend of the water inventory shadow price in present value is increasing over time with a decreasing rate, whereas the seasonal .peaks and troughs in water demand produce positive and negative shifts from that trend and suggest a peak load‐pricing system. The marginal productivity of water is related to rental prices of the different equipment types and to capital equipment marginal cost. The latter sets up an upper bound for water prices. Increasing returns to scale are treated by integer programing formulation when setup costs or indivisibility of projects violate the concavity of the objective function.
Splash erosion related to soil erodibility indexes and other forest soil properties in Hawaii
Authors: Yamamoto Teruo , Anderson Henry W.
Published: February 2008

Soil losses under simulated rainfall were used to test indexes of erodibility based on soil aggregate size and Middleton's suspension percent. Soil samples were collected on the Koolau and Waianae ranges on Oahu, Hawaii. Soil losses expressed as gross splash erosion and maximum splash rate were related by regression on principal components to eight factors: soil erodibility index, bulk density, saturation soil moisture content, precipitation excess, organic matter content, geologic type, vegetation type, and climatic zone at the sampling site. Equations that included the percent of water stable aggregates 0.25–0.50 mm in size produced the highest explained variation: 81% in gross splash erosion and 66% in maximum splash rate. Gross splash was related to a soil erodibility index, bulk density, and infiltration and saturation moisture content; in contrast, maximum splash erosion variation was related to organic matter content as well as to an erodibility index and the bulk density of the soil. Ash and basalt colluvium soils require more careful management than basalt soils because of their higher maximum splash rates.
Unsteady flow toward an artesian well
Authors: Huang Yang H.
Published: February 2008

A finite element method programed for a high‐speed computer was developed to determine the unsteady drawdown around an artesian well. On the basis of assumptions that the well has a finite radius and that the discharge from a partially penetrating well is not uniform along the well bore, numerical solutions for various well penetrations are presented and compared with the experimental measurements from a sand model. It was found that the numerical solutions check reasonably with the experimental measurements; thus the validity of the numerical method was indicated.
Hydrologic studies using the Boussinesq equation with recharge term
Authors: Zucker Melvin B. , Remson Irwin , Janet Ebert , Aguado Eduardo
Published: February 2008

The Boussinesq equation, which is used to describe one‐dimensional unconfined ground water movement, is modified to accept groundwater recharge as computed by a climatological soil‐moisture balance. It is solved efficiently by using a predictor‐corrector technique for nonlinear partial differential equations. The method is applied to studies of the effects of system parameters on groundwater and to the determination of system parameters by the inverse method. It is used to predict the effects of certain land development options on groundwater occurrence and on groundwater discharge to streams.
Effects of artificial aeration on the chemistry and algae of two Michigan Lakes
Authors: Fast Arlo W. , Moss Brian , Wetzel Robert G.
Published: February 2008

Two lakes were artificially aerated by using compressed air. Section Four Lake, an unproductive lake, was completely mixed, whereas Hemlock Lake, a eutrophic lake, had its hypolimnion aerated but thermal stratification maintained. Chemical and algal changes in Section Four Lake during destratification were not great. Although phytoplanktonic production potentials increased during mixing, the phytoplankton standing crop appeared to decline slightly, possibly due to the increased mixing depth and turbidity. Hemlock Lake hypolimnetic anoxia and conditions associated with it were eliminated during aeration. The lake gradually destratified during aeration due to leaks in the aeration tower. These leaks also released nutrient rich water into the epilimnion, which promoted algal growth.
Relation between evapotranspiration rate and maize yield
Authors: Hillel Daniel , Guron Yair
Published: February 2008

Water use efficiency is evaluated in terms of the ratio of dry matter yield to seasonal evapotranspiration. A 5‐year maize irrigation experiment was conducted in which the root zone soil moisture balance and crop response were measured in relation to potential and actual evapotranspiration. A threshold evapotranspiration of 250–300 mm was indicated below which production was negligible and above which production rose linearly with the amount of water applied. Water use efficiency increased with higher quantities of irrigation provided that soil aeration was not impeded and potential evapotranspiration was not exceeded. It is concluded that a ‘wet’ irrigation regime, permitting the crop to transpire at a rate approaching the climatically induced potential and simultaneously preventing the occurrence of moisture deficits, can help to realize the full productivity of the crop.
Potential for marginal cost pricing in water resource management
Authors: Hanke Steve H. , Davis Robert K.
Published: February 2008

Demand management through pricing is assessed as a means to control use and influence investment in water resources. In the assessment of various pricing policies, trade offs are considered: economic efficiency, investment information, administrative and transaction costs, equity, and political acceptability. On the basis of these trade offs, eight water resource areas are evaluated for their potential for improved pricing. Four areas in water resources show promise for using improved pricing policies: municipal water services, industrial and municipal sewerage, navigation, and flood damage reduction and shoreline protection. Four other areas for various reasons present serious problems: outdoor recreation, fish and wildlife habitat, irrigation, and hydroelectric power.
Point processes of seasonal thunderstorm rainfall: 1. Distribution of rainfall events
Authors: Smith R. E. , Schreiber H. A.
Published: February 2008

The hot rainy season marked by local scattered thunderstorms from June to September is typical of most of the lower elevations of the Sonoran and Chihuahuan regions of south‐western North America. This rainy season is analyzed by using long‐term historical daily records to obtain insight concerning the underlying stochastic process. By using historical data from three scattered points in this region, we computed the discrete series of daily Bernoulli parameters and daily first‐order Markov transition probabilities. The hypothesis of sequential independence versus a first‐order Markov dependence hypothesis is tested by comparison of analytically derived distributions for dependent random variables generated by the nonstationary processes. These include wet and dry run lengths, occurrence of the first wet day in the season, number of runs per season, and total number of rainfall days per season. The comparative analysis of historical data indicates that (1) the Markov chain model is generally significantly superior to the Bernoulli model (which extends results of similar analyses by others from regions of largely frontal‐type storms) and (2) year‐to‐year variations in the process require additional probabilistic descriptions, indicated by annual variance in number of rain days and significant annual changes in autocorrelation properties.
Regular meander path models
Authors: Ferguson R. I.
Published: February 2008

Existing mathematical models for regular meander paths are shown to be members of a general family of differential equations in which the rate of change of curvature along the channel is an odd function of path direction and bends are symmetric. The physical assumptions of the general model and possible justifications of the particular cases are outlined. Each model is specified by one scale parameter (path or axial wavelength) and one shape parameter (maximum deviation, sinuosity, or maximum curvature). Exact analytic expressions for geometric properties of circular arcs, Fargue's spiral, Von Schelling's curve, and the sine‐generated curve are presented and illustrated by dimensionless plots; the last three models are generally similar. Properties of natural meander bends show fair agreement with these three regular models, although bend size and shape vary along individual channels, possibly because of nonuniform floodplain topography and sediments.
Economic study of the effect of municipal sewer surcharges on industrial wastes and water usage
Authors: Elliott Ralph D.
Published: February 2008

Many cities in the United States are considering surcharges on industrial wastes having a strength greater than domestic wastes because (1) waste treatment costs have been rising, (2) taxpayers are reluctant to allow substantial increases in their water and sewer rates, and (3) the Environmental Protection Agency is requiring as a precondition for their grants that industries pay an equitable share of municipal waste treatment costs. Cities can make decisions about these charges by knowing the effect of surcharges on industrial wastes discharged into municipal systems and on the quantity of water demanded from municipal systems by industrial firms. Data obtained from 34 cities in the United States that have been using surcharges substantiated the negative relationships hypothesized among prices and quantities. Introducing an average surcharge of $27.00/1000 Ib of BOD causes a 45% reduction in industrial wastes. This surcharge also results in a 42% reduction in the industrial use of water. The level of confidence in these results is expressed in terms of probabilities in the final parts of the last two sections of this paper.
Evaporation and cooling of a lake under unstable atmospheric conditions
Authors: Weisman Richard N. , Brutsaert Wilfried
Published: February 2008

The problem involves turbulent diffusion of momentum, sensible heat, and water vapor in the lower atmosphere when a neutral, dry air mass encounters a warm, wet surface. The water surface temperature is specified, and the surface roughness is taken to be constant over land and water. The turbulent fluxes are formulated by a semiempirical turbulence theory with the Businger‐Dyer form of the Monin‐Obukhov similarity functions, a water vapor buoyancy term in the Obukhov stability length, and Blackadar's scaling height in the mixing length. The resulting solution of the equations of conservation shows that the stability discontinuity at the leading edge can greatly affect the mean rate of evaporation and that the vertical vapor flux can greatly contribute to the atmospheric stability. The solution is relatively insensitive to the exact form of the Monin‐Obukhov similarity functions or to the exactness of Reynolds' analogy or von Karman's constant. For large fetches and near‐neutral conditions the solution becomes similar to that obtained in Sutton's problem and with Harbeck's empirical formula.
Nutrient losses after clear‐cut logging and slash burning in the Oregon Coast Range
Authors: Brown George W. , Gahler Arnold R. , Marston Richard B.
Published: February 2008

Nutrient release from three small watersheds in Oregon's Coast Range was monitored for 2 years before and 2 years after logging. One watershed, Flynn Creek (203.14 ha), served as an untreated control. Deer Creek (303.32 ha) was patch‐cut. No change in the concentration or yield of nitrate nitrogen, phosphorus, or potassium was observed after logging. Needle Branch (70.68 ha) was clear‐cut and burned. Maximum nitrate nitrogen concentrations increased from 0.70 to 2.10 mg/1. Nitrate nitrogen concentrations returned to prelogging levels by the sixth year after logging. Yield of nitrate nitrogen increased from 4.94 to 15.66 kg/ha the first year after treatment. Potassium concentrations increased markedly after burning from about 0.60 to 4.40 mg/1 but returned to prelogging levels within 2 months. Phosphorus concentrations were unchanged. These changes pose no threat to aquatic or terrestrial productivity.
Practical application of fractional Brownian Motion and noise to synthetic hydrology
Authors: Chi M. , Neal E. , Young G. K.
Published: February 2008

A synopsis of self‐similar stochastic processes is presented with special emphasis on fractional Brownian motion and noises. Detailed analysis and discussion are on the approach of ‘fast fractional Gaussian noises’ by Mandelbrot and his collaborators. Modifications are incorporated and parameter selection criteria suggested so that the method becomes simpler, more flexible to use, and easier to follow. A step‐by‐step procedure is included for convenience of application.
Trend surface analysis and seasonal distribution patterns of primary nutrients and chlorophyll in unstratified Gulf Coast estuaries
Authors: Cechova Irina , Davis Ernst M.
Published: February 2008

The technique of data display, the synographic mapping system (Symap), was applied in ecological studies of unstratified Gulf Coast estuaries. Thirty‐four computer maps of spatial distribution of primary nutrients and chlorophyll concentrations in San Antonio and Matagorda (Texas) estuaries were prepared from survey data covering the period 1970‐1971. The maps provided a convenient means for detecting the sources of estuarine enrichment by primary nutrients and of seasonal changes in dispersion patterns. Weighted average concentrations of each compound in the entire estuarine water mass were determined from such displays and used in comparison of concentrations for different months of the survey period. The data presented on Symap displays were used in the determination of mixing and exchange efficiency in the estuaries. The results indicated that incoming nutrients often have very short residence times. Behavior of the nutrients followed patterns similar to those discussed by Pritchard (1954). It was demonstrated, however, that the efficiency of exchange and residence time of each compound vary significantly within a year, conditioned by variable compound loading, quantity of tributary runoff, range of tidal activity, and variable biological food demand. An attempt was made to relate the chlorophyll a concentrations obtained as weighted averages from Symap displays to concentrations of phosphorus, nitrogen, and carbon, to the amount of tributary runoff, and to yearly seasons by means of coaxial graphical correlation.