bluuebunny/crossref_metadata_2025 huggingface dataset:
Horton's Law of Stream Numbers
Authors: Scheidegger A. E.
Published: February 2008

The possibilities for obtaining a rational explanation of Horton's law of stream numbers are reviewed. The previous explanations of the stream‐number law by (1) a growth model referring to generations of rivers and by (2) statistical graph‐theory are compared. The graph‐theoretical explanation seems superior to the other model of Horton's law, inasmuch as it produces not only the form of the law, but even, numerically, the naturally observed bifurcation ratio. It is also independent of the structural properties of the river net.
Moments of the Input, Output, and Impulse Response Functions of Linear Systems About Arbitrary Points
Authors: Diskin M. H. , Boneh A.
Published: February 2008

A general expression is derived for the relation between the moments of the output, input, and impulse response functions of lumped linear time invariant systems about any three arbitrary points along the time axis. The derivation is given both by a method based on integration and summation operations and by a method using Laplace transforms. The latter method also gives the influence on their output of initial time lags in the input and in the impulse response function of linear systems.
The Sediment Yield of Major Rivers of the World
Authors: Holeman John N.
Published: February 2008

The amount of suspended sediment transported by rivers to the seas each year is tabulated. The major rivers are ranked in order of tons of sediment transported per year and drainage area and water discharge data are included. The rivers are listed by, continents in subsequent tables with data on drainage area, annual sediment yields in tons, sediment production rates in tons per square mile per year, the years of sediment measurement, and the sources of data. This sample represents more than one‐third of the land contributing water‐borne sediment to the seas and, if representative, indicates an annual world sediment yield of 20 billion (20 × 109) tons. The data suggest that Africa, Europe, and Australia have very low sediment yields (<120 tons per square mile per year), South America's rate is low, North America's is moderate, and Asia's is high to the degree of yielding up to 80% of the sediment reaching the oceans annually.
Congressional Handling of Water Resources
Authors: Schad Theodore M. , Boswell Elizabeth
Published: February 2008

In the 89th Congress, 1289 legislative measures, more than 5% of the total number introduced, were concerned with water resources. The United States Congress, patterned on experience in Great Britain, embodies the theory of the separation of powers expressed in the United States Constitution. To handle the heavy legislative work load, proposed legislation is considered first in committee before debate on the floor. The committees thus have great power in shaping the nature of legislation. Under the present committee structure many factors other than water resources have been given predominance. As a result, under the rules of the Senate and House of Representatives governing referral of bills, water resources measures were referred to 11 committees in the Senate and 13 committees in the House of Representatives. Although there are some instances where inconsistent policies have evolved in water resources programs because the legislation emanated from different committees, there are others where committees have cut across jurisdictional lines to propose legislation that provides uniform policies applicable to all Federal programs. The authors do not suggest a more rational basis for assigning committee jurisdiction over water resources matters.
Horton's Laws of Stream Lengths and Drainage Areas
Authors: Scheidegger Adrian E.
Published: February 2008

Most customary explanations for Horton's metric laws of stream lengths and drainage areas are based on the idea that in river nets one can speak of cycles or generations of rivers. However, this customary explanation presupposes certain topological features in river basins that do not seem to occur in nature. Hence, the theory in which river nets are assumed to be simply random connections of channels is further applied. Upon this basis, a rational explanation of the two metric laws is obtained which is free from any specific structural assumption regarding a river net.
The Steady‐State Measurement of the Relation between Hydraulic Conductivity and Moisture Content in Soils
Authors: Smiles D. E. , Towner G. D.
Published: February 2008

A simple method of analysis is proposed for use with steady‐state measurements to determine the relation between hydraulic conductivity and moisture content of soils. It is noted that the effect of membrane impedance may be overcome by the use of a simple experimental procedure.
Predicting Temperatures of Small Streams
Authors: Brown George W.
Published: February 2008

Hourly temperatures of small streams can be accurately predicted using an energy balance. Micrometeorological measurements are required to assess the environment of the small stream accurately. The temperature‐prediction technique was tested on three streams in Oregon. On unshaded stretches, net all‐wave radiation is the predominant energy source during the day; evaporation and convection account for less than 10% of the total energy exchange. Conduction of heat into the stream bottom is an important energy balance component on shallow streams having a bedrock bottom. Up to 25% of the energy absorbed by such a stream may be transferred into the bed. Hourly temperature changes of 0–16°F were predicted to within 1°F more than 90% of the time. This technique permits foresters to control water temperature through manipulation of stream‐side vegetation.
Surface Resistance of Crop Canopies
Authors: Szeicz G. , Long I. F.
Published: February 2008

Three analytic and two emperic methods are described to calculate the surface resistance rs of crops transpiring at a measured rate. The profile method is applicable when detailed temperature, humidity, and wind profiles are measured; for the residual method, measurements of surface temperature, wind, and humidity are enough; for the heat balance method, the calculation is based on the ratio of potential to actual evaporation. For rough estimates, an empiric equation of Monteith or a relation between leaf area and surface resistance can be used. In southern England and in California all three analytic methods agree closely. Hourly values of rs in California demonstrate the effect of water stress on an irrigated grass canopy by midday, whereas in England the rs of a barley crop is maintained constant for almost the whole day. From Aslyng's measurements of evaporation, the relation of rs to soil‐water potential is calculated and used to show how relative rates of transpiration and photosynthesis may change in response to water stress. For an equatorial rain forest in Kenya, mean monthly rs varied systematically with soil moisture deficit, ranging between 0.3 and 1.1, sec cm−1.
Effect of Sediment Concentration on Well Recharge in a Fine Sand Aquifer
Authors: Rahman Md. Ataur , Smerdon Ernest T. , Hiler Edward A.
Published: February 2008

A model recharge well was constructed to simulate recharge into wells in a fine sand aquifer. The sand in the model aquifer was uniform fine sand and had a uniformity coefficient of 1.25 and an effective diameter of 144 microns. Both clear tap water and sediment laden water were used for recharge. Sediment laden water was obtained by mixing 50% bentonite and 50% kaolinite with tap water. Sediment concentrations were 100, 200, and 500 ppm. The piezometric surfaces near the recharge well were measured during the tests. Migration of sediment into the aquifer was determined by sampling the aquifer sand after the tests at predetermined distances from the well. The sediment in the recharge water highly affected the rate of recharge. During the period of the tests a reduction in hydraulic conductivity of the model aquifer of 15–46% occurred as a result of recharge with sediment laden water. Most of the sediment deposited in the aquifer was retained near the well screen.
A Game Theory Approach to the Problems of International River Basins
Authors: Rogers Peter
Published: February 2008

The lower Ganges and the Brahmaputra rivers flow out of India and join together in the province of East Pakistan to form one of the major river systems in the world. Each year the rivers flood during the monsoon, causing loss of life and great damage to crops and property. The problem is further exacerbated by the fact that the best flood control points in the basin are not under the political control of Pakistan, which suffers most from the floods. The number of possible combinations of structural and nonstructural variables for this river system is so large that conventional methods of analysis are inadequate. We demonstrate that by use of systems analysis techniques, including linear programing and game theory, we are able to consider a rational plan to control the floods while taking advantage at the same time of the complementarities which exist between flood control and other possible uses for the river, such as power production, irrigation, navigation, and salinity control. Moreover using the concepts of game theory we are able to investigate a range of strategies for cooperation between the two riparian nations which will result in significant benefits to each.
Theory of Flow in a Confined Two Aquifer System
Authors: Neuman Shlomo P. , Witherspoon Paul A.
Published: February 2008

A complete analytic solution has been developed for the problem of flow to a well in a confined infinite radial system composed of two aquifers that are separated by an aquitard. The well, which is represented by a line sink, completely penetrates only one of the aquifers and discharges at constant rate. The present solution differs from previous work in that the effects of storage in the aquitard and drawdown in the unpumped aquifer are both considered. Asymptotic solutions for small values of time are also included. The analytic solutions have been evaluated numerically for selected cases. The validity of these solutions has been verified independently using the finite element method of analysis.
Determination of Aquifer Diffusivity from Aquifer Response to Fluctuations in River Stage
Authors: Pinder George F. , Bredehoeft John D. , Cooper Hilton H.
Published: February 2008

The diffusivity of a homogeneous isotropic aquifer can be determined from the response in the aquifer to fluctuations in river stage. Observed changes in head in the aquifer are compared with theoretic head values computed assuming a series of diffusivities. These values are generated by approximating the stage hydrograph as a series of discrete steps and summing the influence of each increment. The diffusivity of the aquifer is calculated from the best‐fitting theoretic response curve. Diffusivities computed for an aquifer at Musquodoboit Harbour, Nova Scotia, agree with values determined from pumping test and digital model analysis.
Robustness of the rescaled range R/S in the measurement of noncyclic long run statistical dependence
Authors: Mandelbrot Benoit B. , Wallis James R.
Published: February 2008

The rescaled range R(t, s) / S(t, s) is shown by extensive computer simulation to be a very robust statistic for testing the presence of noncyclic long run statistical dependence in records and, in cases where such dependence is present, for estimating its intensity. The processes examined in this paper extend to extraordinarily non‐Gaussian processes with huge skewness and/or kurtosis (that is, third and/or fourth moments).
A laboratory study of surface runoff due to moving rainstorms
Authors: Yen Ben Chie , Chow Ven Te
Published: February 2008

The movement of a rainstorm determines the spatial and temporal distributions of the rainfall over a watershed and hence affects the characteristics of the flow on the watershed. In this study the importance of the movement of rainstorms on the time distribution of the surface runoff from watersheds is demonstrated through the use of a laboratory watershed experimentation system. Experiments were performed on the impervious square watershed for 2 rainfall intensities, 4 surface slopes, and 14 rainstorm velocities. Analysis of the mechanics of water flowing on watersheds is attempted to explain the influence of movement of rainstorms on the characteristics of surface runoff hydrographs.
Determining aquifer characteristics by the tidal method
Authors: Carr P. A. , Van Der Kamp G. S.
Published: February 2008

If ground‐water levels of a confined aquifer fluctuate with sea tides, individual values of hydraulic conductivity and specific storage can then be determined. Apparent tidal efficiency and time lag are first calculated from the water level data recorded at an observational device situated inland from the sea, taking into account the response characteristics of the observational device according to criteria established by Hvorslev [1951]. The true tidal efficiency of the aquifer at the seacoast is then determined from the apparent tidal efficiency and used to obtain the specific storage. This and the tidal time lag are utilized to calculate the hydraulic conductivity. The method was tested in Prince Edward Island, Canada, and yielded results compatible with pump test data. This is a simple and inexpensive way to test a confined aquifer in the coastal environment.
Spatially varied flow equations
Authors: Chow Ven Te
Published: February 2008

The momentum and energy principles are equally applicable in the derivation of spatially varied flow equations. By applying the energy principle and introducing a slope of energy head Se, the resulting spatially varied flow equation takes a different form of several terms containing the slope and the effect of added or extracted discharge from the equation derived by applying the momentum principle and using the frictional slope Sf. The two slopes, however, become identical if V = V* = V0 and if the flow is steady.

The spatially varied flow equation is the same for flow with either increasing or decreasing discharge. In some cases of steady flow, however, the condition V = V* = V0 occurs in flow with decreasing discharge and V* = 0 occurs in flow with increasing discharge; the resulting equations will differ in the coefficient of the term containing the effect of the added or extracted discharge, as shown by equations 5 and 16.
A Working Model for the Variation in Stream Water Chemistry at the Hubbard Brook Experimental Forest, New Hampshire
Authors: Johnson Noye M. , Likens Gene E. , Bormann F. H. , Fisher D. W. , Pierce R. S.
Published: February 2008

Stream water chemistry varies hyperbolically with stream discharge through four decades of discharge change within the Hubbard Brook Experimental Forest, New Hampshire. This dilution process is most simply explained by the mixing of rain water or surface water with deeper soil water. The resultant mixture of waters subsequently appears as stream water. Sodium and silica concentrations in stream water are markedly diluted during high discharge periods while hydrogen ion, aluminum, and nitrate concentrations are increased. Magnesium, calcium, sulfate, chloride and potassium concentrations are changed very little by stream discharge variations. During the summer, biologic activity measurably reduces the concentration of nitrate and potassium in stream water.
Applications of the Theory of Runs to Hydrology
Authors: Rodríguez‐Iturbe Ignacio
Published: February 2008

The problem of runs is one of long history among hydrologists. Classically a run is defined as a sequence of observations of the same kind preceded and succeeded by one or more observations of a different kind.

Considering a sequence of random variables xn, n = 0, 1, 2,. and choosing a constant x0, one may arbitrarily classify the nth year as a surplus year if xn > x0 and call xn − x0 the surplus. Similarly if xn ≤ x0, the nth year is a deficit year with the deficit x0 − xn [Downer et al., 1967].
Optimal Taxing for the Abatement of Water Pollution
Authors: Hass Jerome E.
Published: February 2008

The Dantzig‐Wolfe decomposition algorithm is posited as a method of finding the optimal treatment configuration for meeting water quality standards along a river basin and simultaneously determining optimal pollution taxes to achieve this configuration when the central authority does not know treatment cost functions. Simulated use of the algorithm using actual data from the Miami River of Ohio indicates that the algorithm performs these tasks satisfactorily. The implications of this analysis are that a central authority can, through a planning (tatonnement) process involving proposed taxes and polluter responses, effectively determine a set of near‐optimal pollution taxes without complete knowledge of treatment costs (i.e., without complete treatment cost functions) in relatively few iterations

A detailed model of the constraint set is formulated in the appendix, which is available on microfiche along with the entire article. Order from the American Geophysical Union, Suite 435, 2100 Pennsylvania Ave., N.W., Washington D.C. 20037. Document W70‐001; $1.00. Payment must accompany order.
Time Distribution Characteristics of Rainfall Rates
Authors: Huff F. A.
Published: February 2008

Data from a 50‐storm sample on two dense networks in Illinois were used to investigate the time distribution of 1‐minute rainfall rates in warm‐season storms. Absolute and relative variability were analyzed for point and mean rates on areas from 25 to 100 square miles. Several variability measures were employed including sequential variability that uses both the magnitude and the sequence of rates in characterizing the time distribution. Since the variability parameters were found to fit closely a log normal distribution, probability distributions were constructed to define interstorm variability relations. Both absolute and relative variability showed a wide range within and between storms, and between areas of different size. Little difference in variability properties was noted between rain and synoptic weather types associated most frequently with warm‐season storms. No evidence of regular oscillations in the time distribution of rainfall rates in convective storms was shown by lag correlation analyses.
An Experimental Investigation of Runoff Production in Permeable Soils
Authors: Dunne Thomas , Black Richard D.
Published: February 2008

In an area of low intensity rainfall and permeable soils, three hillside plots were instrumented for a study of runoff‐producing mechanisms. Runoff from the plots was measured at the ground surface, the base of the root zone, and in the zone of perennial groundwater seepage. Data on soil moisture, water‐table elevation, and piezometric head were also collected during natural and artificial storms. The data showed that, as the infiltration capacity of the soil exceeded the rainfall intensities that occurred and that were applied, overland flow generated by the mechanism described by Horton did not occur. Although soils and topography were those generally thought to be conducive to subsurface stormflow, the runoff produced by this mechanism was too small, too late, and too insensitive to fluctuations of rainfall intensity to add significantly to stormflow in the channel at the base of the hillside. When the water table rose to the surface of the ground, however, overland flow was generated on small areas of the hillside. Only when this overland flow occurred were significant amounts of stormflow contributed to the channel by the hillside. The return periods of storms that would produce such overland flow were found to be very large.
Stream Order as a Measure of Sample Source Uncertainty
Authors: Sharp W. E.
Published: February 2008

The Horton stream order at the outlet of a drainage basin is a direct measure of the uncertainty (entropy) of the source supplying any discrete particle or atom detected at the outlet. Ifmis the order of the main stream in a basin, the uncertainty that the source lies in the drainage area of anith order tributary is given bym‐i. This may be interpreted as representing the minimum number of tests or samples needed to find a single contamination source in a sequential search of a drainage basin. Similarly Scheidegger's consistent stream order may be interpreted as being the number of samples required to search a basin for a single source when the link magnitude of the outlet is known. Because natural streams usually have multiple contaminant sources and cannot be expressed as a simple branching process, a convenient estimate of the average number of samples needed to find a single source is given by (rb‐ 1) (m‐i) whererbis the bifurcation ratio.
Hysteresis in Two Sands and the Independent Domain Model
Authors: Talsma T.
Published: February 2008

Hysteresis in the relations between moisture content, potential, and conductivity was measured on two sands, one fine grained and the other coarse and angular grained. Hydraulic conductivity was determined during steady flow at selected capillary potentials. Water uptake and release from the samples was measured volumetrically at equilibrium points using multistep increments of capillary potential. Sets of primary draining and wetting scanning curves were obtained for both sands. Anomalies existed in the total water release and uptake for both main branch and scanning curves of the coarse sand. Considerable hysteresis occurred in the moisture content‐potential and conductivity‐potential relationships but little, if any, hysteresis was observed in the moisture content‐conductivity relationships. The independent domain theory of hysteresis predicted the scanning curves moderately well for the greater part of the hysteresis regions. Significant deviations were found in the high moisture content range in the fine grained sand.
Some Problems of Prioing under Stochastic Supply Conditions: The Case of Seasonal Pricing for Water Supply
Authors: Crew M. A. , Roberts G.
Published: February 2008

Two models of seasonal pricing, a deterministic supply model and a stochastic supply model, are used to solve the problem of pricing and investment in water supply under certain assumptions. The stochastic model provides prices for one period. Extensions to more periods might be achieved through numerical methods and the aid of computers.
Nonlinear Time Varying Model of Rainfall‐Runoff Relation
Authors: Chiu Chao‐Lin , Huang J. T.
Published: February 2008

The developed nonlinear time varying model of a hydrologic system that relates the rainfall and the runoff is represented by a pair of nonlinear ordinary differential equations with time varying coefficients. The model does not require the linearity and time invariance assumptions necessary in conventional unit hydrograph methods. The nonlinear and time varying characteristics of the system are incorporated into the model through four basic system parameters. These parameters can be determined by the procedure developed without using the equations of the model. The nonlinearity and long‐, medium‐, and short‐term time varying trends of a rainfall‐runoff system can be determined and described by analyzing the parameters. The model is empirical and its field application procedure is feasible and simple, since its derivation is based on the physical system response observed. In an illustrative field application the model and procedure proved effective, relative to other linear and/or time invariant models, in predicting the rainfall‐runoff relation, especially when the rainfall excess occurred during a very short time interval.
Recession and the Baseflow Problem
Authors: Appleby F. Victor
Published: February 2008

Baseflow as a hydrograph component is discussed with special reference to Hall's [1968] paper ‘Base‐Flow Recession—A Review’. Additional references with particular emphasis on the baseflow problem are given. A three parameter baseflow partition functional is shown to give substance to the concept of ‘group persistence’ and to suggest an underlying mechanism to the Hurst statistical phenomenon.
Mean Evaporation over Canada
Authors: Ferguson H. L. , O'Neill A. D. J. , Cork H. F.
Published: February 2008

Mean monthly and annual maps of evaporation over Canada have been prepared, and examples are presented. The maps represent time and space averages of evaporation from natural open water bodies having negligible heat storage. The analysis is based on 5‐year class A evaporation pan data supplemented by 10‐year climatologic data from 100 stations across Canada. The Christiansen formula is shown to be superior to other formulas tested for approximating pan data from other standard climatologic observations. The analysis takes account of the seasonal effects of freeze‐up and breakup on the availability of open water. A zonal classification of lake evaporation that emphasizes the large‐scale climatic variations in this parameter across Canada is proposed.
A Stochastic Model for Flood Analysis
Authors: Todorovic P. , Zelenhasic E.
Published: February 2008

A stochastic model, based on the recent developments in the theory of extreme values, is presented to describe and analyze excessive streamflows. The model is a particular stochastic process x(t) defined as the maximum term among a random number of random observations in an interval of time [0, t]. Since the number of hydrograph peaks in [0, t] that exceed a certain level x0 and the magnitudes of these peaks are random variables, the foregoing model seems to conform well to the flood phenomenon. The passage time T(x) of the process x(t) relevant to the risk evaluation in the design of hydraulic structures is also considered. The results obtained are applied on the 72‐year record of the Susquehanna River at Wilkes‐Barre, Pennsylvania. Theoretical and observed results agree reasonably well.
Topological and Geometrical Properties of Braided Streams
Authors: Howard Alan D. , Keetch Mary E. , Vincent C. Linwood
Published: February 2008

Strong relationships among dimensionless properties of braided streams indicate that similarity is preserved in streams with the same average number of channels but of different sizes. The degree of braiding in streams, conveniently measured by the average number of channels bisected by lines crossing the channel, increases with the product of discharge and gradient, but decreases with higher variance in discharge. A random walk simulation model of braiding duplicates many of the numerical relationships observed in natural streams, suggesting that most of the downstream variation in the number of channels in braided streams is explainable by local fluctuations in discharge and sediment in transport, as opposed to large‐scale factors such as valley constriction.
Reducing Excess Readouts from Digital Streamflow Recorders
Authors: Hibbert Alden R. , Casner Wilson B.
Published: February 2008

Digital water level recorders on small, flashy streams are frequently set at 5‐minute readout intervals to define fluctuations during critical storm flow periods. Consequently, during nonstorm periods far more data points are punched on the recorder tapes than are needed to define the long‐term hydrograph. A two‐step reduction process eliminates more than 95% of the original 105,000 data points per year of record. The first reduction is obtained by translating to IBM cards only every twelfth (hourly) head value punched on the tape during nonstorm periods. Storm periods are translated at 5‐minute intervals. A computer reduction step on both hourly and 5‐minute data then systematically rejects head values not essential to hydrograph definition. Rejection is based on differences in elevation and slope between successive head values. Computer output consists of cards and a listing of the reduced data.
Public Perceptions of Water Quality
Authors: David Elizabeth L.
Published: February 2008

Water pollution is perceived by the general public to be of increasing concern as a major problem facing the state. From a survey of a representative sample of adults in Wisconsin, it was shown that the public has rather definite ideas about what constitutes a description of pollution. The respondents mentioned algae and murky, dark water but did not often mention attributes such as chemicals or disease germs that are not detected by the human sensory system. When the respondents were asked to name water in the state that they felt was polluted, they named waters that in fact have the characteristics they described when defining pollution. The most widely used indicators of water pollution seem insufficient in light of the public definition of, and concern about, water pollution.
Antitranspirant Effects on the Transpiration and Physiology of Tamarisk
Authors: Brooks Kenneth N. , Thorud David B.
Published: February 2008

Five‐stamen tamarisk, an important phreatophyte in the southwestern United States, is difficult to eradicate for water salvage. There also is increasing opposition to its eradication because this species provides cover for wildlife and greenery in the environment. The application of nontoxic antitranspirant sprays to reduce tamarisk transpiration may be an alternative to eradication. We tested several antitranspirants, including a combination of the monomethyl and monoglyceryl esters of n‐decenylsuccinic acid (MDSA‐GDSA), 8‐hydroxyquinoline sulfate (8‐HQS), and phenylmercuric acetate (PMA), on tamarisk in greenhouse and field environments. PMA was toxic at a concentration of 0.001 M and was therefore not considered in the evaluation described below. The effects of MDSA‐GDSA and 8‐HQS on transpiration, growth, net photosynthesis, dark respiration, relative stomatal apertures, chlorophyll and protein contents, and foliage temperature were evaluated. Transpiration rates of plants treated with MDSA‐GDSA and 8‐HQS were 25–35% less than those of control plants for 20 days in the greenhouse and for at least 5 days in the field. Growth was reduced for 2–3 weeks, and net photosynthesis for less than 1 week. The other physiological factors were not changed substantially. Foliage temperatures increased 2°–3°C for 3 days following treatment in the field. Further study for possible management application is suggested.
Soil Piping and Stream Channel Initiation
Authors: Jones Anthony
Published: February 2008

The hydrologic significance of soil piping has been generally ignored. Piping has been associated primarily with drylands, yet evidence of piping is available from a large range of climatic regions. In particular, soil piping is found to be widespread in the United Kingdom. Preferred locations for piping are either just above or within a horizon of low relative permeability and low aggregate stability. Chemical environment may range from acidic moorland soils to saline marshes. There are significant trends to lower aggregate stability and coarser grain size (particularly in the range above 250 μm) in the bed of a pipe than in the roof. Many pipes in the areas studied appear to be dormant or relatively inactive and may well be in approximate equilibrium with the soil pore and channel subsystems. However, when equilibrium is destroyed (e.g., by stream incision) pipes can form loci for channel extension. Studies of the spatial distribution of outlets show that to create normal channel networks, pipe clusters within the ensemble and, similarly, individual pipes within those clusters must be selected on an unequal basis. A low density random selection from pipes located on percolines would fulfill the requirements. The presence of piping may have a significant effect on the form of the hydrograph.
Analysis of Nonsteady Flow with a Free Surface Using the Finite Element Method
Authors: Neuman Shlomo P. , Witherspoon Paul A.
Published: February 2008

A new iterative, numerical approach to nonsteady flow of groundwater with a free surface using the finite element method has been developed. The method is unconditionally, stable and therefore requires only a small number of time steps to reach the steady state. It can handle problems in which the free surface is discontinuous and portions of the free surface are vertical or nearly vertical. Infiltration or evapotranspiration at the free surface is handled with ease, and the effect of the unsaturated zone can be taken into account indirectly by using the concept of delayed yield from storage. In addition to gravity drainage, the method takes into consideration storage due to the elastic properties of the saturated porous medium. In problems involving flow to a well operating at a prescribed rate, both storage in the well and the actual distribution of velocities along the well bore are taken into account. The method can be applied to a wide variety of problems involving complex boundaries and arbitrary degrees of heterogeneity and anisotropy. Several examples are included to demonstrate some of the features of this new approach.
Motion of the Seawater Interface in Coastal Aquifers: A Numerical Solution
Authors: Shamir U. , Dagan G.
Published: February 2008

The partial differential equations that describe the motion of the seawater interface and the free surface in a phreatic coastal aquifer (or the freshwater head replacing the latter, in the confined case) are presented. They are based on the Dupuit approximation and take into consideration the geometry of the vertical section through the aquifer, in whose plane the flow takes place, as well as the spatial variation of properties of the porous medium and the spatial and temporal distributions of accretion, recharge, and pumping. An implicit numerical scheme is presented to solve the set of simultaneous partial differential equations. The scheme is based on a linearization of the equations and employs a grid with one spacing over the intrusion length and a different spacing in the remainder of the field. Efficient solution of the resulting set of simultaneous linear equations for each time step is achieved by arranging them in a way that results in a 7 diagonal coefficient matrix. Examples are presented, for which the numerical solutions are compared with analytical solutions or laboratory experiments.
The Sinusoidal Function of Regional Monthly Average Relative Pan Evaporation
Authors: Dalinsky Joseph S.
Published: February 2008

An analysis was made of data from 47 stations at which evaporation had been measured by means of U.S. Weather Bureau class A pans protected by wire mesh. The stations represent different climatic conditions ranging from subhumid to arid. The stations are situated on the Mediterranean coast, in the desert (the Arava Valley), in valleys, in plains, and in mountains. The average relative evaporation in each month was found to be equal at all the stations and could be expressed as a sinusoidal function. The small deviations from the sinusoidal function make computation of correlations superfluous. As a result of this finding, it is possible to estimate the average evaporation rates for every month and for every location in the country by using one parameter (the amplitude of the sine function) and a map of average annual evaporation depths.
Mechanical Sampler for Determining the Water Quality of Ephemeral Streams
Authors: Knedlhans S.
Published: February 2008

A simple mechanical system for automatically sampling small ephemeral streams is described. A rack fitted with two columns of bottles and a float assembly permits sampling of both rising and falling stages at predetermined water depths.
Soil Water Hysteresis in Silt Loam and Clay Loam Soils
Authors: Topp G. C.
Published: February 2008

The microhydrologic properties involving water content, pressure head, and hydraulic conductivity were measured simultaneously for a silt loam and for a clay loam soil. Large hysteresis in the water content‐pressure head relationship was found for both soils, the silt loam soil showing the larger amount. There was no measurable hysteresis in the relationship between hydraulic conductivity and water content in either soil. The data from the clay loam soil showed considerable scatter attributed to structural rearrangement in the soil during measurement. A formulation of the independent domain theory by Everett was unsatisfactory for predicting the observed scanning curves in the water content‐pressure head relationships of both soils. A theorem of an alternative formulation by Enderby was tested by comparing differences in slopes for reversals from drying to wetting along the main curves to those found on a scanning curve; Enderby's formulation was probably no better for the silt loam soil under the conditions of test than that of Everett.
Empirical Study of Economic‐Ecologic Linkages in a Coastal Area
Authors: Hite James C. , Laurent Eugene A.
Published: February 2008

An input‐output model was adapted to estimate the environmental repercussions of changes in the economic structure of the Charleston, South Carolina, metropolitan area. The model contains two basic elements: (1) the Leontief inverse of a regional input‐output matrix, and (2) an environmental matrix containing data on resource use or residuals emission per dollar of gross output for each sector of the input‐output matrix. Implementation of the model is achieved by postmultiplying the environmental matrix by the Leontief inverse. The results show the cumulative effects on the local environment of both the direct and indirect changes resulting from changes in the economy structure of the area, and these results provide a basis for estimating the environmental repercussions of alternative changes in the local economy.
Adequacy of Markovian Models with Cyclic Components for Stochastic Streamflow Simulation
Authors: Rodriguez‐Iturbe Ignacio , Dawdy David R. , Garcia Luis E.
Published: February 2008

The concept of deterministic hydrologic cycles is questioned from physical and statistical points of view. The spectra of streamflow series are shown to vary with time, and this variation suggests the nonstationary character of the data. Demodulation techniques are used to study the statistical character of the amplitude and phase of the annual streamflow cycle, and the use of the results in models for simulation is suggested. A case study performed with several Markovian type models shows that the seasonal variation in the standard deviation should be incorporated in any model used for design. It is also shown that the type of distribution used for the random component does not have a great influence on streamflows generated for storage design. Great care should be taken when using logarithmic models because they may produce very distorted synthetic traces when improperly used.
Some Problems of Flood Analysis
Authors: Todorovic P. , Rousselle J.
Published: February 2008

This paper is a continuation of a previous one in which a stochastic model for analyzing excessive streamflows was presented. The model was based on the assumption that flood peak exceedances are independent, identically distributed random variables and that their occurrence is subject to the Poisson law. In the present paper a model is developed for nonidentically distributed exceedances on the assumption that only those exceedances during a particular season may be considered identically distributed. From this hypothesis the distribution function of the maximum flood peak exceedance in an arbitrary interval of time (0, t] is determined. The results are then applied to the 72‐year record of the Greenbrier River at Alderson, West Virginia. The theoretical and observed results agree reasonably well.
Analysis of Alpine Waters by Ion Electrode Methods
Authors: Reynolds R. C.
Published: February 2008

Ion electrode procedures are described for determining SO4, Cl, Ca + Mg, K, and Na for waters of low salinity (<30 ppm). Anion‐cation balances average discrepancies of ±4.2%. Waters derived from glaciers and containing fine rock flour give significantly higher results for Na and K by atomic absorption methods than by electrode methods. It is concluded that suspended mineral matter in glacial waters interferes significantly with atomic absorption alkali determinations and that for the analysis of such waters, ion electrode techniques are superior.
Effect High Intensity Storms on Soil Slippage on Mountainous Watersheds in Southern California
Authors: Rice R. M. , Foggin G. T.
Published: February 2008

The conversion of brush areas to grassland increased soil slip erosion on mountainous watersheds in southern California during the intense winter storms of 1969. The incidence of soil slippage, site factors affecting slope stability, and amount of debris generated by slippage were investigated for sample brush and grass areas in the San Dimas Experimental Forest. Soil slippage occurred on 5.5% of the brush areas and 16.7% of the grass areas, the values for both areas being about twice those measured in 1966 for a less intense storm period. The effectiveness of linear discriminant analysis was below that of 1966. In all probability, the thresholds of several environmental factors are not linear, and the 1969 storms crossed the thresholds of several factors responsible for more widespread slippage.
An Analysis of the Laws of Stream Order for Fibonacci Drainage Patterns
Authors: Sharp W. E.
Published: February 2008

The interpretation of a Fibonacci tree as a stream drainage pattern leads to an exact description of all the stream order properties by Fibonacci numbers. The asymptotic bifurcation ratio for both Horton and Strahler orders is the special constant 1 +rwhereris the famous golden ratio 1.618….
Probability Distribution of Number of Networks in Topologically Random Network Patterns
Authors: Dacey Michael F.
Published: February 2008

The probability distribution of the number of channel networks for Werner's model of topologically random network patterns is shown to obey a shifted negative or inverse hypergeometric probability law and, when the number of exterior links is large, to be approximated by a shifted negative binomial probability law.
Application of the convolution equation to stream‐aquifer relationships
Authors: Hall Francis R. , Moench Allen F.
Published: February 2008

Flow and head variations in stationary linear stream‐aquifer systems are obtained through application of the convolution equation. Four highly idealized cases involving finite and semi‐infinite aquifers, with and without semipervious stream banks, are considered. Equations for the instantaneous unit impulse response function, the unit step response function, and the derivative of the unit step response function are given for each case. Head fluctuations in the aquifer due to an arbitrarily varying flood pulse are obtained for the cases involving a finite aquifer with and without a semipervious stream bank. Flow in and out of the aquifer at the stream bank is determined for the same cases and demonstrates the value of the convolution equation in evaluating the base flow. Head variations, and to a lesser extent flow variations, are apparently relatively insensitive to variations in aquifer diffusivity.
Irrigation planning: 4. Optimal interseasonal water allocation
Authors: Dudley Norman J.
Published: February 2008

A series of models has been developed in previous papers to estimate the best sized area to develop for irrigation from a given reservoir under conditions of variable supply and demand for irrigation water. The best operating policies for such a system were also derived. The approach of this paper extends the previous approach by recognizing the value of water carried over from one season to the next. A modified version of the previous approach is used to generate reservoir level transition probabilities and expected benefits. A dynamic programing model is then used to estimate the expected benefits from allocating water optimally between seasons. These expected benefits are a function of acreage developed for irrigation and beginning‐season reservoir levels. Such a function allows a decision maker at any decision point within an irrigation season to equate the expected net benefits from allocating water to the rest of the current season with the expected net benefits from saving such water for the following season. This decision‐making process is simulated for a number of seasons. The results of an application of the models indicate that such interseasonal transfer can considerably increase the present value of expected benefits from the project.
Soil water regime in economic evaluation of salinity in irrigation
Authors: Bresler E. , Yaron D.
Published: February 2008

A field irrigation experiment and computer and statistical models are used to estimate the functional relationships between the total soil water suction and the man‐controlled variables, the quantity and salinity of the water, and the irrigation frequency. It is estimated that the seasonal average soil water suction S in the root zone increases with each of the variables: the irrigation interval, water salinity, and initial soil salinity. The value of S also increases with the amount of irrigation water Q at low values of Q, but decreases with Q at relatively high values of Q. Under the conditions studied, it is more efficient to use given quantities of irrigation water (from the standpoint of salinity) for changing the soil water regime rather than for leaching. An approach to the economic evaluation of the optimal combination of water quantity and salinity in the short run is outlined. This approach is based on a previous empirical estimate of the effect of water suction on yield, and on the present estimate of the functional relationships between the total soil water suction and the man‐controlled irrigation variables.
Learning, external benefits, and subsidies in water desalination
Authors: Rausser Gordon C. , Willis Cleve , Frick Peter
Published: February 2008

In the absence of the recognition of learning in new technologies such as desalting, water resource investment decisions may be erroneous for two reasons. First, neglecting cost reductions over time due to ‘learning by doing’ leads to the overestimation of costs. Second, since learning in a particular desalting plant may result in external learning benefits to other plants, these externalities may serve as the basis for the determination of a subsidy intended to internalize these benefits. Accordingly, this paper provides estimates of learning (cost) functions for large‐scale seawater distillation plants. To incorporate prior information into the estimation process, Bayesian methods are used. Alternative specifications of these learning functions are then employed in the context of a measure of external learning benefits to estimate by computer simulation the moments of these benefits. A discussion ensues concerning how such a measure can be employed in various water resource decision models.
Numerical treatment of the unsaturated water flow equation: Comparison of experimental and computed results
Authors: Giesel W. , Renger M. , Strebel O.
Published: February 2008

A numerical solution of the differential equation governing the unsaturated vertical water flow in soils is described and applied to results of infiltration and redistribution experiments carried out in a sand column in the laboratory by Vachaud and Thony. Hysteresis effects are taken into consideration. The experimental results were verified.
Heat and mass transfer of freezing water‐soil system
Authors: Kennedy G. F. , Lielmezs J.
Published: February 2008

To describe multiphase water (water vapor, ice, water liquid) distribution in freezing soil, mass and heat transfer equations using the methods of processes of irreversible thermodynamics are presented.
One‐dimensional consolidation of a clay layer with impeded drainage boundaries
Authors: Mesri Gholamreza
Published: February 2008

In many field transient water flow problems of practical interest the main source of settlement is a single compressible layer bounded above and below by layers that contribute little to total settlement but that have coefficients of permeabilities and thicknesses such that they can be considered neither freely draining nor impervious. Furthermore, the top and bottom drainage layers can have unequal permeabilities and thicknesses. An analytical solution to the one‐dimensional consolidation of a clay layer with unlike drainage boundaries is developed, and the results are presented in the form of percent consolidation versus time factor to facilitate their use by engineers.