bluuebunny/crossref_metadata_2025 huggingface dataset:
Policy Sciences in Water Resources Research
Authors: Cummings Ronald G.
Published: February 2008

As the newly appointed Policy Sciences Editor for this journal, I would like to take this opportunity to introduce myself to WRR's readership as well as to offer a few comments concerning my views of policy sciences in water resources research.

I am an economist working in the area of natural resources and environmental management. As such, I've spent a good part of my research career working with noneconomists. During 1969–1972, I worked in Mexico with hydrologists and engineers from Mexico's Water Resources Ministry in efforts to assess management/investment programs for reservoir systems and systems for interbasin water transfers. Between 1972 and 1975, while serving as Chairman of the Department of Resource Economics at the University of Rhode Island, my research involved collaborative efforts with biologists and soil scientists in studies concerning the conjunctive management of reservoirs for agricultural and lagoon systems and the control of salinity levels in soils and aquifers. Since 1975, at which time I joined the faculty at the University of New Mexico, I have worked with engineers at the Los Alamos National Laboratory in developing operation/management models for hot, dry rock geothermal systems and, more recently, with legal scholars and hydrologists in analyses of water rights issues. Thus I am comfortable with and appreciative of research conducted by my colleagues in systems engineering, operations research, and hydrology, as well as those in economics, law, and other social sciences.
Managing Water Scarcity: An Evaluation of Interregional Transfers
Authors: Vaux H. J. , Howitt Richard E.
Published: February 2008

An interregional trade model is developed for assessing the potential of limited market institutions to alleviate water scarcity. The model differs from those of Takayama and Judge, since curvilinear demand functions are employed and an unequal number of supply and demand regions are specified. The model is applied to California using regional supply and demand functions estimated for 1980, 1995, and 2020. The results show that water transfers can be substituted for new supplies to the extent that less than 100,000 ac ft (123 × 106 m3) of new capacity could be justified by 2020. The net benefits to buyers and sellers total $66 million for 1980 and rise to $219 million by 2020. The work also demonstrates that trade would lead to premature drawdown of groundwater resources in the absence of management and might create excess supply capacity for urban regions.
The Use of Models for Water Resources Management, Planning, and Policy
Authors: Friedman Robert , Ansell Christopher , Diamond Stuart , Haimes Yacov Y.
Published: February 2008

The Office of Technology Assessment (OTA) of the U.S. Congress investigated the current and potential use of water resource‐related mathematical models. It focused on mathematical modeling as a means of assessing the broader issue of the nation's ability to analyze and plan courses of action to deal with current and long‐range water problems. OTA found that models capable of analyzing many pressing water resource issues are currently available and that these models have significant potential for increasing the accuracy and effectiveness of information available to managers, decisionmakers and scientists. Surveys and workshops conducted by OTA, however, indicate that institutional constraints to modeling—including inadequate Federal support services for model dissemination, training, and technical assistance, and maintenance—have impeded modeling from realizing its full potential. The states, in particular, are hard pressed to fulfill their present responsibilities without an improved capacity to use the best available analytical tools, which they rely on the federal government, in part, to provide. Many major federal agencies, however, lack an integrated plan for developing and supporting models; in the absence of a comprehensive strategy, federal agencies are often unresponsive to both state and federal problem‐solving needs.
Flux‐Averaged and Volume‐Averaged Concentrations in Continuum Approaches to Solute Transport
Authors: Parker J. C. , van Genuchten M. Th.
Published: February 2008

Transformations between volume‐averaged pore fluid concentrations and flux‐averaged concentrations are presented which show that both modes of concentration obey convective‐dispersive transport equations of identical mathematical form for nonreactive solutes. The pertinent boundary conditions for the two modes, however, do not transform identically. Solutions of the convection‐dispersion equation for a semi‐infinite system during steady flow subject to a first‐type inlet boundary condition is shown to yield flux concentrations, while solutions subject to a third‐type boundary condition yield volume‐averaged concentrations. These solutions may be applied with reasonable impunity to finite as well as semi‐infinite media if back mixing at the exit is precluded. Implications of the distinction between resident and flux concentrations to laboratory and field studies of solute transport are discussed. It is suggested that perceived limitations of the convection‐dispersion model for media with large variations in pore water velocities may in certain cases be attributable to a failure to distinguish between volume‐averaged and flux‐averaged concentrations.
Eulerian‐Lagrangian Solution of the Convection‐Dispersion Equation in Natural Coordinates
Authors: Cheng Ralph T. , Casulli Vincenzo , Milford S. Nevil
Published: February 2008

The vast majority of numerical investigations of transport phenomena use an Eulerian formulation for the convenience that the computational grids are fixed in space. An Eulerian‐Lagrangian method (ELM) of solution for the convection‐dispersion equation is discussed and analyzed. The ELM uses the Lagrangian concept in an Eulerian computational grid system. The values of the dependent variable off the grid are calculated by interpolation. When a linear interpolation is used, the method is a slight improvement over the upwind difference method. At this level of approximation both the ELM and the upwind difference method suffer from large numerical dispersion. However, if second‐order Lagrangian polynomials are used in the interpolation, the ELM is proven to be free of artificial numerical dispersion for the convection‐dispersion equation. The concept of the ELM is extended for treatment of anisotropic dispersion in natural coordinates. In this approach the anisotropic properties of dispersion can be conveniently related to the properties of the flow field. Several numerical examples are given to further substantiate the results of the present analysis.
Parameter Identification of Groundwater Aquifer Models: A Generalized Least Squares Approach
Authors: Sadeghipour Jamshid , Yeh William W‐G.
Published: February 2008

This paper concerns the methods of estimating aquifer transmissivities on the basis of unsteady state hydraulic head data. Traditionally, the criterion of minimizing the sum of the squares of errors has been used to match the observed data with the model response. The data used for optimization usually contain noise that is not necessarily uncorrelated. It is well understood that the results of identification methods are very sensitive to measurement errors in data. In this study, the ordinary least squares (OLS) technique is carried out along with a generalized least squares (GLS) technique specifically designed to reduce the effect of correlated errors. The trace of the covariance matrix is used as a measure of overall accuracy and reliability of the estimated parameters. The effectiveness of the OLS and GLS techniques in dealing with noisy data is demonstrated by using a hypothetical example. The results of numerical experiments suggest that GLS offers a promising approach in efficiently improving the reliability of the estimated parameters.
Contaminant Transport in Fractured Porous Media: Analytical Solution for a Two‐Member Decay Chain in a Single Fracture
Authors: Sudicky E. A. , Frind E. O.
Published: February 2008

An analytical solution is presented for the problem of radionuclide chain decay during transport through a discrete fracture situated in a porous rock matrix. The solution takes into account advection along the fracture, molecular diffusion from the fracture to the porous matrix, adsorption on the fracture face, adsorption in the rock matrix, and radioactive decay. The solution for the daughter product is in the form of a double integral which is evaluated by Gauss‐Legendre quadrature. Results show that the daughter product tends to advance ahead of the parent nuclide even when the half‐life of the parent is larger. This is attributed to the effect of chain decay in the matrix, which tends to reduce the diffusive loss of the daughter along the fracture. The examples also demonstrate that neglecting the parent nuclide and modeling its daughter as a single species can result in significant overestimation of arrival times at some point along the fracture. Although the analytical solution is restricted to a two‐member chain for practical reasons, it represents a more realistic description of nuclide transport along a fracture than available single‐species models. The solution may be of use for application to other contaminants undergoing different types of first‐order transformation reactions.
An Analytical Solution for the Effects of Abstraction From a Multiple‐Layered Confined Aquifer With No Cross Flow
Authors: Wikramaratna R. S.
Published: February 2008

The problem of abstraction from a well penetrating a multiple‐layered aquifer, each layer being independently homogeneous, isotropic, and artesian, is considered. For the two‐layered case with a constant abstraction rate, an analytical solution is derived for the aquifer response. The solution is simplified to give an expression for the drawdown in the well, and it is shown that for certain special cases the two‐layered solution reduces to an existing solution for the equivalent single‐layered aquifer. The effects of aquifer stratification on the response in the well are investigated by comparing the solutions for different parameter values.
An Analysis of the Influence of Fracture Geometry on Mass Transport in Fractured Media
Authors: Smith Leslie , Schwartz Franklin W.
Published: February 2008

A stochastic modeling technique has been developed to investigate mass transport within a network of discrete fractures. The fracture network is composed of two orthogonal fracture sets, with fracture length, location, and aperture characterized by appropriate probability distributions. Emphasis is placed on understanding how fracture geometry influences mass transport within a network of discontinuous fractures. The network is aligned in such a manner that one fracture set (set one) forms the dominant pathway for transport. The primary role of the second fracture set is to provide connecting pathways between the discontinuous fractures of set one. Results suggest that mass transport can be described in terms of the directness of the connection between the upstream and downstream boundaries. Variations in fracture geometry which have the effect of increasing the probability that a relatively indirect or circuitous pathway exists through the network generally lead to an increase in both the mean and the standard deviation in the arrival time of various breakthrough fractions. Examples include a reduction in the number of fractures forming the set aligned with the direction of the hydraulic gradient or a decrease in the average length of fractures forming that set. Variations in fracture geometry which have the effect of increasing the probability that a relatively direct pathway will exist through the network have the opposite effect. Transport is sensitive to the variability in fracture aperture. The connectivity of the fracture network is also shown to influence the magnitude of dispersive effects.
Migration of Radionuclides in Fissured Rock: Analytical Solutions for the Case of Constant Source Strength
Authors: Rasmuson Anders
Published: February 2008

An analytical solution is derived for the problem of radionuclide migration in fissured rock, where the rock blocks are modelled as spheres. The solution differs from a previous one mainly in the inlet boundary condition. In the present paper the case of constant source strength is treated instead of a decaying step release. The solution developed here is considerably more complex. Processes that are accounted for are advection and longitudinal dispersion in the fissures, external and internal diffusion into spherical rock blocks, sorption onto the fissure surfaces, and sorption within the matrix and radioactive decay. The solution is obtained in the form of an infinite single integral depending in general on six dimensionless parameters. The steady state solution includes five dimensionless quantities. A comparison with previously published results for a system of parallel fractures is made. It is shown that if the area‐to‐volume ratio of the slabs and the spherical rock blocks is the same, identical breakthrough curves are produced for short and long contact times. In the intermediate range the solution with spherical rock blocks will give earlier breakthrough and higher steady state concentrations. It is shown that the analytical solution for parallel fractures, previously given as an infinite double integral, may be derived as an infinite single integral. The numerical evaluation is thereby considerably simplified. Examples demonstrate the impact of hydrodynamic dispersion and water transport time on radionuclide transport in situations considered to be realistic repository conditions.
Sediment production from forest road surfaces
Authors: Reid Leslie M. , Dunne Thomas
Published: February 2008

Erosion on roads is an important source of fine‐grained sediment in streams draining logged basins of the Pacific Northwest. Runoff rates and sediment concentrations from 10 road segments subject to a variety of traffic levels were monitored to produce sediment rating curves and unit hydrographs for different use levels and types of surfaces. These relationships are combined with a continuous rainfall record to calculate mean annual sediment yields from road segments of each use level. A heavily used road segment in the field area contributes 130 times as much sediment as an abandoned road. A paved road segment, along which cut slopes and ditches are the only sources of sediment, yields less than 1% as much sediment as a heavily used road with a gravel surface.
The development of tributaries of different sizes along winding streams and valleys
Authors: Abrahams Athol D.
Published: February 2008

An analysis of 40 winding streams and valleys reveals that a higher proportion of large tributaries than small ones occurs on the concave (out) side of bends. The principal reason for this is that large tributaries experience greater difficulty than small ones forming in the limited amount of space on the convex (in) side of bends. The proportions of small and large tributaries on the concave side of bends are determined largely by the spatial requirements of tributaries, valley sinuosity, mean valley bend length, and mean rate of bend migration. In addition, the proportion of large tributaries on the concave side of bends is affected by junction angle adjustments that deflect a main stream toward a large tributary, thereby creating a bend with the large tributary on its concave side. These adjustments increase the proportion of large tributaries on the concave side of bends, especially along low‐sinuosity headwater streams.
Modeling subsurface stormflow on steeply sloping forested watersheds
Authors: Sloan Patrick G. , Moore Ian D.
Published: February 2008

Five mathematical models for predicting subsurface flow were compared to discharge measurements made by Hewlett and Hibbert (1963) on a uniform sloping soil trough at the Coweeta Hydrologic Laboratory. The models included one‐ and two‐dimensional finite element models based on the Richards equation, a kinematic wave model, and two simple storage‐discharge models based on the kinematic wave and Boussinesq assumptions. The simple models simulated the subsurface response and water table positions as well as the more complex models based on the Richards equation and were much more economical to use from the point of view of computational costs. Such models have features that would allow them to be incorporated into more complex watershed models, thus placing hydrologic prediction on a more physically correct and less empirical footing.
A model of flood wave speed—Discharge characteristics of rivers
Authors: Wong Tony H. F. , Laurenson Eric M.
Published: February 2008

Recent wave speed‐discharge investigations carded out on six Australian river reaches show consistent variations of wave speed with discharge and provide new knowledge in this area with applications in both flood routing and runoff routing. A model developed to define the wave speed‐discharge relation is described. The model is based on concepts of the physical factors affecting the wave speed‐discharge haracteristics of natural channels. It provides for overbank discharge as well as main channel flow. The applicability of the model is demonstrated using data from the six reaches.
Transfer Function Models of Daily Urban Water Use
Authors: Maidment David R. , Miaou Shaw‐Pin , Crawford Melba M.
Published: February 2008

A time series model of daily municipal water use as a function of rainfall and air temperature is developed. Total water use is separated into base use and seasonal use. The seasonal use series is detrended, then a nonlinear heat function relating water use to air temperature during rainless periods is employed to deseasonalize the series. The residuals are modeled using Box‐Jenkins transfer functions with transformed rainfall and air temperature as independent variables. The model is applied to daily data from Austin, Texas from 1975 to 1981 and accounts for 97% of the variance of daily municipal water use over that period. Forecasts of daily usage are made for a two‐week lead time.
A Note on Higher‐Order Corrections of the Head Covariances in Steady Aquifer Flow
Authors: Dagan Gedeon
Published: February 2008

Average uniform flow takes place in a heterogeneous aquifer of infinite extent. The input to the problem is the hydraulic conductivity, which is regarded as a random space function that is lognormal, stationary and statistically isotropic. The output is the water head field, which is a random function satisfying the equation of steady flow. The first‐order approximation of the head, in an asymptotic expansion for small log‐conductivity variance, is a normal function characterized completely by the head‐log‐conductivity cross‐covariance and the head covariance or variogram. These covariances are proportional to the log‐conductivity variance. By using spectral methods, second‐order corrections of the head covariances, proportional to the log‐conductivity variance squared, are derived explicitly. Detailed calculations are carried out for an exponential log‐conductivity covariance. The main finding of the note is that the first‐order approximation is very robust and even for a log‐conductivity variance equal to unity, the second‐order correction of the head variances is smaller than 10% of the first‐order approximation.
Dynamic model for multireservoir operation
Authors: Mariño Miguel A. , Loaiciga Hugo A.
Published: February 2008

This paper presents a methodology to obtain optimal reservoir operation policies for a large‐ scale reservoir system. The model yields medium‐term (one‐year‐ahead) optimal release policies that allow the planning of activities within the current water year, with the possibility of updating preplanned activities to account for uncertain events that affect the state of the system. River flows are characterized as a multivariate autoregressive process and are forecasted using maximum likelihood estimators. The solution method is a sequential dynamic decomposition algorithm that keeps computational requirements and dimensionality problems at low levels. The model maximizes the system annual energy generation while satisfying constraints imposed on the operation of the reservoir network. Several alternative versions of the model are also presented, which can be used under different assumptions. The model is applied to a large‐scale multireservoir system, the northern portion of the California Central Valley Project. The optimal release policies show a potential increase in the system total annual energy with respect to heuristic schedules currently in use.
Minimum variance streamflow record augmentation procedures
Authors: Vogel Richard M. , Stedinger Jery R.
Published: February 2008

Traditional approaches for augmentation of short‐streamflow records have exploited the cross‐correlation among flows at two or more gages to obtain maximum likelihood estimates of the mean and variance of the flows at the short‐record gage. While such estimators asymptotically have minimum variance among all asymptotically unbiased estimators, they are not necessarily optimal for the small samples of interest in hydrology. Improved estimators of the mean and variance of the flows at the short‐record gage are developed. The gains in information transfer associated with the use of both the traditional and improved estimators of the mean and variance are documented. Monte‐Carlo results illustrate the performance of these estimators when the true cross‐correlation of the flows must be estimated. The information transfer gains when the true cross‐correlation must be estimated are comparable to the gains achieved when the cross‐correlation is known. The potential advantages and limitations of these new estimators are discussed within the framework of augmentation and/or extension of both peak annual floods and also monthly streamflow records.
Nitrogen and phosphorus speciation and flux in a large Florida River Wetland System
Authors: Elder John F.
Published: February 2008

Hydrologic measurements and analyses of various nitrogen and phosphorus species were made on the Apalachicola River system in northern Florida in 1979 and 1980. Annual outflows of total nitrogen (TN) and total phosphorus (TP) were not substantially different from annual inflows. However, there was significant net import of ammonia and soluble reactive phosphorus and net export of some particulate and organic species. The TN: TP ratio ranged from 12 to 15, but the specific ratio of dissolved inorganic nitrogen: soluble reactive phosphorus was much higher (up to 40) and increased in a downstream direction; this contributed to a phosphorus‐limiting situation in Apalachicola estuary. Processes within the flood plain ecosystem accounted for much of the release of organic and particulate species and retention of inorganic species. This flood plain function is probably critical for maintaining a nutrient pool in the estuary which supports secondary productivity and a detrital‐based food web.
Conservation Using a Rate of Return Decision Rule: Some Examples from California Municipal Water Departments
Authors: Mercer Lloyd J. , Morgan W. Douglas
Published: February 2008

A significant alternative to physical rationing of water to achieve conservation is provided by the price system. To act like profit maximizing firms, municipal water utilities (MWD's) should price their water so as to earn the opportunity cost of capital (the market rate of return) on the assets. The actual internal rate of return is calculated for a sample of 30 California MWD's for a 12‐year period. For the 26 MWD's with a rate of return less than 10%, iterative simulations are run with increases in the MWD's average price to achieve the target rate of return. The magnitude of water conservation using the rate of return rule is reported for three alternative price elasticities of demand. The new implicit prices necessary to achieve the target rate of return are shown to be less than the cost of the cheapest new surface supply.
Multivariate Analysis and Interpretation of the Hydrochemistry of a Dolomitic Reef Aquifer, Northern Italy
Authors: Seyhan E. , Van De Griend A. A. , Engelen G. B.
Published: February 2008

Regionalization based on multivariate statistical analyses of hydrochemical data and environmental isotopes proved most successful in differentiating groundwater of different hydrogeological origins within the Sasso Lungo dolomitic mountain stock, Northern Italy. The approach used chemical and isotopic data to evaluate hydrologic properties normally determined by more traditional techniques. From field and laboratory studies of 19 hydrochemical variables measured at 46 sampling points, three distinct groups of water types were differentiated, in close agreement with hydrogeological evidence, namely, (1) pure Sciliar dolomite water, (2) water from volcanic deposits, and (3) mixed water from Sciliar dolomite and volcanic deposits. Environmental isotopes are used to support hydrogeological observations arid the hydrochemical analyses and also to provide valuable additional information for further distinction between hydrogeological subsystems. The data show that the dolomite aquifer discharges from two main subsystems: (1) relatively young, shallow to moderately deep waters in the central part of the reef stock and (2) older groundwater discharging at the rims of the reef.
A Field Example of Measuring Hydrodynamic Dispersion in a Single Fracture
Authors: Novakowski Kentner S. , Evans Gordon V. , Lever David A. , Raven Kenneth G.
Published: February 2008

A field example of measuring the dispersive properties of a single fracture in fractured plutonic rock is presented. The experimental technique involves injecting a slug of conservative tracer into a “steady” groundwater flow field established between a pumping and recharging borehole and monitoring the tracer breakthrough by sampling the withdrawal water directly. The breakthrough curves from two experiments were analyzed with a model which describes the flow field geometry either analytically or numerically and solves for hydrodynamic dispersion analytically. A longitudinal dispersivity of 1.40 m was estimated by fitting the model to each set of field data. The magnitude of the dispersion was determined to be independent of dispersive effects created by flow through the borehole instrumentation and thought to be purely hydrodynamic in nature.
Surface Irrigation Advance Motion After Gate Closure
Authors: Weir G. J.
Published: February 2008

A kinematic wave model of border dike irrigation is presented in which surface discharge per unit width varies as the square of surface depth, and the cumulative infiltration is a linear function of the opportunity time. Analytic approximations are presented for the motion of the advance front after gate closure. These results, which are usually accurate to within one 1%, are obtained by considering the surface water profile at the instant the depletion characteristic reaches the advance front, and the subsequent advance motion, to have originated from an idealized, fictional water source concentrated about the gate at the time of gate closure. The corresponding Lewis‐Milne problem is also briefly discussed.
Field and Laboratory Measurements of Snow Liquid Water by Dilution
Authors: Davis Robert E. , Dozier Jeff , LaChapelle Edward R. , Perla Ron
Published: February 2008

Field trials of the dilution technique for measuring snow liquid water content show that the refined procedure is rapid and simple. Measurements of the liquid water mass fraction with an absolute error of ∼1.5% can be obtained by one operator at a rate of 10–15 samples per hour, but if the water content is low (0–2%), the relative error can be high. Electrolytic conductivity is the preferred method for measuring concentrations, using a stock solution of 0.01 N HCl. The recommended amount of stock solution to add is 0.5–0.8 times the mass of the snow sample. Extraction of the resulting mixture of stock solution and snow liquid water is best done with a screened pipette, instead of by decanting.
A Radar‐Based Stochastic Model for Short‐Time‐Increment Rainfall
Authors: Kavvas M. Levent , Herd Kenneth R.
Published: February 2008

In order to model the rainfall depths at time scales smaller than or equal to 1 day a radar‐based conceptualization of ground rainfall is developed. This conceptualization states that rainfall in time at any ground location can be described by the rainfall intensity distribution over the trajectories which are drawn by the ground location point on the rain fields that pass over this location. As such, this conceptualization uses the information on the rain fields that are detected on the weather radar plan position indicator scope. Using this conceptualization, a single‐site stochastic model is developed in order to describe the evolution of rainfall depths at all time scales smaller than or equal to 1 day. The model has the structure of a filtered Poisson cluster process. A statistical application of the model to the simultaneous radar and rain gage data is performed. The model is calibrated mainly by a nonparametric procedure using 5‐min‐increment radar microfilm and hourly rain gage data during April. The calibrated model is used first in estimating the rain‐gage‐observed hourly and daily mean rainfall depths during a period which envelops the calibration period plus an extra year's test period during April. The calibrated model is then used in the real‐time radar‐based estimation of hourly rainfall depths during the test period. The results of this application show that, in general, the radar‐based conceptualization developed in this study is a viable approach to the modeling of rainfall depths at time increments smaller than or equal to 1 day.
The Cost Gap Method and Other Cost Allocation Methods For Multipurpose Water Projects
Authors: Driessen T. S. H. , Tijs S. H.
Published: February 2008

Four different cost allocation methods are compared which allocate the joint costs of water resource projects among its participants on the basis of separable and nonseparable costs: the egalitarian nonseparable cost (ENSC) method, the separable costs remaining benefits (SCRB) method, the minimum costs remaining savings method, and a new method, the so‐called nonseparable cost gap method, which is derived from the τ value, a game theoretical concept. All these methods, except the ENSC method, can be described with the aid of lower and upper bounds for the core of the involved cost game. For convex cost games, these three methods use the same bounds for the core and hence coincide, but their cost allocation not necessarily belongs to the core. For a second class of cost games the so‐called one‐convex cost games, all methods, except the SCRB method, coincide, and their cost allocation turns out to be the center of gravity of the core of the involved cost game.
Optimal Control of Nonlinear Groundwater Hydraulics: Theoretical Development and Numerical Experiments
Authors: Willis Robert , Finney Brad A.
Published: February 2008

Nonlinear optimization models are presented for the optimal operation of an unconfined aquifer system. The aquifer's response equations are developed using finite difference methods, quasilinearization, and matrix calculus. The optimization model, which is structured as a discrete time optimal control problem, identifies the optimal pumping pattern necessary to satisfy an exogenous water demand. A quasilinearization optimization algorithm and projected Lagrangian methods are used for the solution of the planning model. Example problems are presented which demonstrate the viability of the approach for nonlinear, nonconvex groundwater management problems.
A Native American View of Western Water Development
Authors: Deloria Sam
Published: February 2008

This paper presents an individual Native American, or American Indian, view of western water development and not necessarily the view of a particular tribe or its government. A disclaimer of this kind is necessary because there has been a historical tendency in this society to look for a single Indian spokesman and search for that spokesman among the Indians who says what society wants to hear. However, the Indian community, while sharing many characteristics and problems, is culturally and politically diverse, and there are no real shortcuts to dealing with it in all its diversity.

Indian water rights, as they relate to western water development, must be seen against the backdrop of the history of the hemisphere. Ever since the arrival of the Europeans on the continent, an important current in the development of the legal system has been to define Indian rights and then develop an orderly process for taking them away. From the formulation of the doctrine of discovery itself, this two‐step exercise has served the humanitarian purpose of attempting to accord some fairness to the Indians while providing discipline to the competition among non‐Indians for the right to use Indian resources. Recognition of full and natural rights of Indian sovereignty and ownership in the hemisphere is commonly viewed as having been a historical impossibility, just as denying them all rights was not practically and morally feasible. The problem then, was and is to balance the two historical necessities appropriately.
Atmospheric CO2 Enrichment of Water Hyacinths: Effects on Transpiration and Water Use Efficiency
Authors: Idso Sherwood B. , Kimball Bruce A. , Anderson Michael G.
Published: February 2008

Open‐top clear plastic wall chambers enclosing pairs of sunken metal stock tanks, one of each pair of which contained a full cover of water hyacinths, were maintained out‐of‐doors at Phoenix, Arizona for several weeks during the summer of 1984. One of these chambers represented ambient conditions, while the other three were continuously enriched with carbon dioxide to approximate target concentrations of 500, 650, and 900 ppm. During a 4‐week period when plant growth was at its maximum, water hyacinth biomass production increased by 36% for a 300–600 ppm doubling of the atmospheric CO2 content, while water use efficiency, or the biomass produced per unit of water transpired, actually doubled. These results are similar to what has been observed in several terrestrial plants and they indicate the general trend which may be expected to occur as atmospheric CO2 continues to rise in the years ahead.
Steady Two‐ and Three‐Dimensional Flows in Unsaturated Soil: The Scattering Analog
Authors: Waechter R. T. , Philip J. R.
Published: February 2008

An exact analog exists between steady quasi‐linear flow in unsaturated soils and porous media and the scattering of plane pulses, and the analog carries over to the scattering of plane harmonic waves. Numerous established results, and powerful techniques such as the Watson transform, are thus available for the solution and understanding of problems of unsaturated flow. These are needed, in particular, to provide the asymptotics of the physically interesting and practically important limit of flows strongly dominated by gravity, with capillary effects weak but nonzero. This is the limit of large s, with s a characteristic length of the water supply surface normalized with respect to the sorptive length of the soil. These problems are singular in the sense that ignoring capillarity gives a totally incorrect picture of the wetted region. In terms of the optical analog, neglecting capillarity is equivalent to using geometrical optics, with coherent shadows projected to infinity. The paper deals specifically with steady infiltration from circular cylindrical and spherical cavities. The asymptotic methods prove remarkably accurate, even far from the limit. The results replace, and explain, previous semiempirical estimates of the limiting behavior. One notable result is that the depth of the penumbra (effectively wetted region) for the cylinder is 128 times the depth for the sphere, confirming and supplementing previous studies. An odd byproduct is that we correct a long‐standing classical result in scattering theory. The scope for extending these methods to flows in other geometries, to heterogeneous soils, and generally to linear convection‐diffusion processes, is indicated briefly.
Topographic Partition of Watersheds with Digital Elevation Models
Authors: Band Lawrence E.
Published: February 2008

Digital elevation models are used to automatically map the stream channel and divide networks of a watershed. These topographic skeletons are used to partition the watershed into a set of fundamental, runoff producing subregions, each of which drains into one stream link. Construction of a code describing the network topology, along with parallel files containing attribute information of each drainage area and associated stream link may form the basis for an efficient watershed information system. Registration of remotely sensed imagery and maps of important soils information to the digital elevation model allows an effective organization of this data as input to hydrologic simulation models. The methodology described here is designed to aid in the efficient parameterization of a distributed components approach to watershed simulation.
Modeling Contamination of Shallow Unconfined Aquifers Through Infiltration Beds
Authors: Ostendorf D. W.
Published: February 2008

We model the transport of a simply reactive contaminant through an infiltration bed and underlying shallow, one‐dimensional, unconfined aquifer with a plane, steeply sloping bottom in the assumed absence of dispersion and downgradient dilution. The effluent discharge and ambient groundwater flow under the infiltration beds are presumed to form a vertically mixed plume marked by an appreciable radial velocity component in the near field flow region. The near field analysis routes effluent contamination as a single linear reservoir whose output forms a source plane for the one‐dimensional, far field flow region downgradient of the facility; the location and width of the source plane reflect the relative strengths of ambient flow and effluent discharge. We model far field contaminant transport, using an existing method of characteristics solution with frame speeds modified by recharge, bottom slope, and linear adsorption, and concentrations reflecting first‐order reaction kinetics. The near and far field models simulate transport of synthetic detergents, chloride, total nitrogen, and boron in a contaminant plume at the Otis Air Force Base sewage treatment plant in Barnstable County, Massachusetts, with reasonable accuracy.
Diffusivity Measurements and Electrical Resistivity Measurements in Rock Samples Under Mechanical Stress
Authors: Skagius Kristina , Neretnieks Ivars
Published: February 2008

If radionuclides are released from an underground repository and enter the groundwater, they would be transported with the moving groundwater in fissures in the rock. Besides fissures the rock also contains micropores filled with stagnant groundwater. If the nuclides are able to diffuse into these micropores, a significant retardation of the nuclides can be expected. At repository depths, the rock is exposed to rather high stresses caused by the large overburden of rock. When drill cores are taken up from the gound, this overburden no longer exists. As a result of this, there might be an increase in the porosity of the rock samples. The effective diffusivity measured in rock samples under atmospheric pressure in the laboratory would then be higher than the effective diffusivity in the rock “in situ.” To simulate the stress that may exist in the bedrock at large depths, diffusion experiments with iodide and electrical resistivity measurements in rock materials under mechanical stress have been performed. It was found that the diffusivity in rock samples at 300–350 bars stress was reduced to 20–70% of the value in the samples under atmospheric pressure. This reduction of the diffusivity in stressed rock is probably of minor importance because of the rather large variation in diffusivity between samples.
Disjunctive Kriging: 1. Overview of Estimation and Conditional Probability
Authors: Yates S. R. , Warrick A. W. , Myers D. E.
Published: February 2008

The disjunctive kriging method described in this paper produces a nonlinear unbiased estimator with the characteristic minimum variance of errors. Disjunctive kriging is as good, or otherwise better than linear estimators in the sense of reduced kriging variance and exactness of estimation. It does not suffer from the difficulties associated with computing the conditional expectation and can be thought of as its estimator. Disjunctive kriging also provides an estimate of the conditional probability that a random variable located at a point or averaged over a block in two‐dimensional space is above some specified cutoff or tolerance level and this can be written in terms of the probability distribution or the density function. The method has important implications in aiding management decisions by providing a quantitative input (which is not readily obtained from the linear kriging estimators), based on the available data, which is the best nonlinear unbiased estimator short of the conditional expectation. A major disadvantage in using disjunctive kriging is the increased computational time. This, however, is mitigated by increased information about the estimate.
The Effect of Serial Correlation on Reservoir Size
Authors: Phatarfod R. M.
Published: February 2008

This paper investigates the effect of the serial correlation coefficient of the inflows on the reservoir size, when large reservoirs are involved. Specifically, it works out reservoir size ratios, i.e., the ratio of the reservoir size when the serial correlations are present to the size when they are neglected, assuming reliability and draft to be the same. When the reservoir is operated on an annual basis, it is shown that for low drafts the ratio is dependent on the inflow model, whereas for the limiting case when the draft ratio approaches the value 1, the ratio is approximately (1 + ρ)/(l − ρ) irrespective of the inflow model, where ρ is the annual serial coefficient. For the case when the reservoir is operated on a seasonal basis, the ratio considered is that of the reservoir size when all the serial correlations are present to the size when the year‐end seasonal correlation is neglected. It is shown that for large reservoirs this ratio is mainly dependent on the annual flow parameters irrespective of the within‐year pattern of inflows.
The Role of Groundwater in Delaying Lake Acidification
Authors: Anderson Mary P. , Bowser Carl J.
Published: February 2008

Models used to study lake acidification generally divide a watershed into several zones or compartments (e.g., soil and groundwater zones) through which water and chemicals are routed. To date most emphasis has been placed on the buffering of acid inputs by chemical reactions in the soil zone. Although buffering in the soil zone undoubtedly is important, the focus of this paper is the role of the groundwater system in delaying lake acidification. In this study, a deterministic approach was selected over the standard parametric modeling used in watershed models. Specifically, an advection‐dispersion model of the groundwater system was linked to a simple groundwater‐rain‐lake mixing model, which in turn was linked to a geochemical speciation and reaction path model. Simulations of hypothetical groundwater‐lake systems utilized chemical data from small lake systems in northern Wisconsin, an area which is currently experiencing acid rain (pH = 4.6) and is potentially sensitive to acid rain impacts owing to the absence of carbonate minerals in the underlying glacial tills and bedrock. Results of the modeling studies demonstrated that even when the effects of chemical reactions are ignored, groundwater inflow can mitigate the effects of acid deposition on lakes. When chemical reactions in the groundwater system were included in the model using a retardation factor, the acidification rate of the lake was significantly decreased. When speciation reactions between lake water and net acid additions were simulated using the geochemical model PHREEQE (Parkhurst et al., 1980), the depression of lake water pH was markedly reduced, indicating that low alkalinity lakes, like the ones in northern Wisconsin, may have appreciable buffering capacity.
The Behavior of Groundwater in the Vicinity of the Water Table Evidenced by Specific Discharge Profiles
Authors: Ronen Daniel , Magaritz Mordeckai , Paldor Nathan , Bachmat Yehuda
Published: February 2008

Detailed vertical profiles of the horizontal component of the specific discharge at the water table region of a phreatic aquifer were obtained, from two research wells, employing both a modified point dilution technique under natural flow conditions and a mathematical diffusion model. H2 18O‐depleted water was used as a tracer. A 2.5‐m multilayer sampler with dialysis cells at 3‐cm intervals was utilized both to introduce the tracer into groundwater and determine its temporal variations. Large variations in the profiles of the tracer concentration were observed in a relatively thin layer just below the water table. The horizontal specific discharge was found to increase with depth from 0.5 m/year in the first 50 cm below the water table to 4.5 m/year at 240 cm depth. Two theories are suggested to explain the presence of an almost stagnant zone at the water table region: (1) the existence of entrapped‐migrating air bubbles which reduce the hydraulic conductivity and (2) drag forces exerted by the capillary fringe.
Importance of the Convergence Criterion in the Automatic Calibration of Hydrological Models
Authors: Isabel Denis , Villeneuve Jean‐Pierre
Published: February 2008

Several publications about the synthetic calibration of deterministic hydrologic models show imprecise experimental results. In order to identify the reason(s) behind this lack of accuracy, a similar experiment was conducted, arid it was observed that the precision of obtained results depended upon the strictness of the convergence criterion. Hence circumspection in the interpretation of results of synthetic calibrations when the convergence criterion is not strict is suggested.
Effects of Suspended Sediment on the Open‐Channel Velocity Distribution
Authors: Coleman Neil L.
Published: February 2008

Experiments were performed in which suspended sediment concentration in open‐channel bounded shear flow was varied systematically while flow depth, slope, and discharge were held essentially constant. The effect of variation in suspended sediment concentration on velocity profile characteristics was investigated. The experiments showed that the Karman coefficient was independent of changes in suspended sediment concentration, while the Coles wake strength coefficient was very sensitive to such changes. The thickness of the logarithmic part of the velocity profile decreased as sediment concentration increased. The logarithmic parts of velocity profiles in sediment‐suspending flow were shifted downward relative to control profiles in comparable clear‐water flows.