bluuebunny/crossref_metadata_2025 huggingface dataset:
Reorientation of urban‐related water resources research
Authors: Whipple William , Hufschmidt Maynard M.
Published: February 2008

A workshop was held at Quail Roost, North Carolina, in July 1975 to develop recommendations for a research program for urban‐related water problems. This article summarizes the workshop recommendations, as finalized by a steering committee, for reorienting current research strategy and priorities. The committee, besides the two authors, included Bernard B. Berger, David H. Howells, L. Douglas James, and Scott Tucker. Basically, the workshop participants concluded that the federal research program on urban‐related water problems is inadequate to meet future needs and is urgently in need of redirection, particularly as it concerns water quality, flood plain management, land‐water interfaces, and governmental institutional arrangements.
Development and application of a water resource allocation model
Authors: Maddaus William O. , McGill John M.
Published: February 2008

A water resource optimization model is described for use in long‐range infrastructure planning for water supply and waste water management. The model includes a network analyzer to determine least‐cost allocation of available sources of water supply (including reclaimed waste water) to various demand points subject to certain physical constraints and water management policies, a recosting procedure for nonlinear cost functions, a digital groundwater model for simulating widespread changes in groundwater depth, and a salt balance model for simulating groundwater quality changes with time. The modeling system provides costs for the optimal water resource allocation for various sets of constraints as well as the environmental changes in the groundwater reservoir, as represented by the number of years until groundwater levels fall to 76 m below 1970 levels and quality of the supply. The most cost‐effective alternative was identified and used to develop a 50‐yr water supply and waste water management plan for the Tucson, Arizona, regional area.
A distributed converging overland flow model: 2. Effect of infiltration
Authors: Sherman Bernard , Singh Vijay P.
Published: February 2008

The overland flow on an infiltrating converging surface is studied. Mathematical solutions are developed to study the effect of infiltration on nonlinear overland flow dynamics. To develop mathematical solutions, infiltration and rainfall are represented by simple time and space invariant functions. For complex rainfall and infiltration functions, explicit solutions are not feasible.
An analysis of the effects of parameter uncertainty in deterministic hydrologic models
Authors: Wood Eric F.
Published: February 2008

The uncertainty in the output of deterministic models, due to the uncertainty in the parameters of the model, is analyzed and compared to current procedures of using average values for the uncertain parameters. The present analysis considers an analytical rainfall‐runoff flood frequency model where the infiltration parameter is considered as a stochastic variable. The same conceptual procedure can be used to analyze fixed but uncertain (unknown) parameters. The extension to analyzing parameter uncertainty in large simulation models is indicated, and the importance of such analyses is discussed.
Strontium isotopes in selected streams within the Susquehanna River Basin
Authors: Fisher R. Stephen , Stueber Alan M.
Published: February 2008

The concentration and isotopic composition of strontium in water samples from the Susquehanna River and its major tributaries between Northumberland, Pennsylvania, and the Chesapeake Bay have been determined to investigate the usefulness of the 87Sr/86Sr ratio as a tracer in hydrologic studies. The87S/86Sr ratios of tributaries, measured just upstream from their confluence with the Susquehanna, show considerable variation, ranging from 0.7091 to 0.7218. These ratios appear to be determined primarily by the local bedrock type and aquifer characteristics. Tributaries whose drainage basins contain important carbonate aquifers have relatively high Sr concentrations and 87Sr/86Sr ratios of about 0.709; where the bedrock is shale with no carbonate rock, the tributaries are characterized by much lower Sr concentrations and 87Sr/86Sr ratios of about 0.716. Tributaries in metamorphic bedrock also have low Sr concentrations and isotopic ratios averaging 0.719. The 87Sr/86Sr ratios of nearly all tributaries in the study area seem to represent a mixture of varying proportions of two distinctly different groundwater types, one with a high Sr concentration and low 87Sr/86Sr ratio, the other characterized by a low Sr concentration and relatively high 87Sr/86Sr ratio. In the northern half of the study area, marked variations in the 87Sr/86Sr ratio of the Susquehanna River indicate incomplete mixing of tributary and mainstream waters, apparently due to the extreme width and small depth‐to‐width ratio of the Susquehanna. Under favorable geologic and hydrologic conditions, strontium isotopes have potential as a tracer of water provenance.
Rainfall network design for runoff prediction
Authors: Bras Rafael L. , Rodríguez‐Iturbe Ignacio
Published: February 2008

A multivariate state‐space stochastic model of rainfall based on a multidimensional rainfall generator suggested by Bras and Rodríguez‐Iturbe (1976a) is used together with a runoff model to study the accuracy of discharge prediction as a function of the rainfall‐sampling network. The runoff model used is a spatially distributed simulation based on a finite difference solution of the kinematic wave equations. Discharge prediction accuracy at any point in a basin can be obtained in terms of the mean square error as a function of the number of rain‐sampling stations, their location, and the errors in sampling devices. The solution is also a function of the physics of the basin at hand which is incorporated in the rainfall‐runoff model. The mean square error of discharge estimation is obtained by using linear estimation theory for dynamic systems. Particularly, the technique used is the Kalman‐Bucy filter, which permits filtering and extrapolation of noisy and incomplete observations.
Multilevel incremental dynamic programing
Authors: Nopmongcol Pradit , Askew Arthur J.
Published: February 2008

An approach to the solution of multidimensional dynamic programs is presented which differs from most decomposition methods currently used in the optimization of water resources systems. The basic concept is directly dependent on certain characteristics of incremental dynamic programing (IDP). The method, referred to as multilevel incremental dynamic programing, results in a marked reduction in computing time and thus increases the power of IDP as a tool in the optimization of multidimensional deterministic systems.
Reliability‐constrained dynamic programing and randomized release rules in reservoir management
Authors: Rossman Lewis A.
Published: February 2008

A stochastic dynamic programing model for determining reservoir release rules which maximize expected net benefits subject to reliability constraints on system performance is presented within the framework of Lagrangian duality theory. The approach characterizes optimal release rules under discounting of benefits as being nonstationary. It also indicates when there exists a randomized rule which dominates the optimal deterministic rule. The methodology for obtaining these rules uses dual optimization to provide bounds on the optimal solution and a branch and bound procedure to resolve any duality gap which may occur if the bounds are not equal. The model is applied to a group of hypothetical problems for which nonoptimal policies had previously been found by using chance‐constrained dynamic programing (Askew, 1974b).
Dissolution kinetics of carbonate rocks: 1. Effects of lithology on dissolution rate
Authors: Rauch Henry W. , White William B.
Published: February 2008

Laboratory dissolution of Middle Ordovician rock samples from central Pennsylvania was studied at 23°C and 1 atm carbon dioxide pressure. Carbonate dissolution rates were compared at 22% bicarbonate saturation with respect to both calcite and dolomite. The results show that carbonate lithology exerts a strong influence on the dissolution rate and hence on the degree of cavity development in karst aquifers. The dissolution rate is most significantly affected by dolomite and impurity content. The rate decreases as percentages of dolomite and disseminated insolubles increase. Maximum dissolution rates occur for carbonate rocks with 1.0–2.5% MgO content and having abundant silty streaks. The sparite content is inversely related to cave development but is independent of dissolution rates measured under the laboratory conditions adopted in this study.
Advances in Box‐Jenkins modeling: 2. Applications
Authors: McLeod Angus Ian , Hipel Keith William , Lennox William C.
Published: February 2008

Recent Box‐Jenkins techniques are employed to determine both nonseasonal and seasonal models for actual time series. The applied examples are carefully explained in order to demonstrate the utility of the new procedures that have been developed for use at the identification, estimation, and diagnostic check stages of model development. Even though more methods are now available for model building, it is demonstrated that this fact enhances rather than complicates the model construction phases. Furthermore, for all three applications considered, better models are obtained than it was previously possible to obtain. A new technique is described for optimal forecasting of the original time series when the data have been transformed by a nonlinear transformation.
Wheat canopy temperature: A practical tool for evaluating water requirements
Authors: Jackson R. D. , Reginato R. J. , Idso S. B.
Published: February 2008

Canopy temperatures were measured on durum wheat grown in six differentially irrigated plots. Soil water content was measured by using a neutron‐scattering technique at two locations within each plot. Water contents, in 20‐cm increments to 160 cm, were determined two to five times per week. Using a sliding cubic smoothing technique, we calculated daily water contents and thus water depletion rates for the entire growing season. Canopy temperatures were measured daily between 1330 and 1400 hours. Air temperatures measured at 150 cm above the soil surface were subtracted from the canopy temperatures to form the difference Tc – Ta. The summation of Tc – Ta over time yielded a factor termed the ‘stress degree day’ (SDD). The SDD concept shows promise as an indicator for determining the times and amounts of irrigations. An expression relating evapotranspiration (ET) to net radiation and Tc – Ta was simplified and tested by using ET measurements with a lysimeter. The expression was used to predict water use by wheat in the six plots. Predicted ET and measured water used agreed reasonably well. The expression may be useful in determining amounts of irrigation water to apply.
Structural flood control planning
Authors: Ball Michael O. , Bialas Wayne F. , Loucks Daniel P.
Published: February 2008

Flood‐routing methods, together with a branch and bound backtracking optimization routine, are used to evaluate alternative capacities and locations of various flood control structures required to protect a floodplain from a specified design flood. This paper describes this preliminary planning procedure and illustrates its use for estimating cost‐effective combinations of flood storage capacities in reservoirs, temporary flood storage basin capacities, levee locations and heights, and increased channel capacities in river basin systems.
Variability of hydraulic conductivity within and between nine Wisconsin soil series
Authors: Baker F. G.
Published: February 2008

Hydraulic conductivity was measured in selected subsurface horizons of nine soil series by using the crust test method. Measurements were made for several moisture potentials in the range 0 > ψm ≥ −150 cm of water at several randomly selected sites per soil series. The morphological character of the soil series spanned a broad range, from sands to clay loam soils. The k characteristic of each series was mathematically described, and the series conductivity curves were related as a family of curves. By using multivariate discriminant analysis the series were grouped into classes of similar hydraulic behavior, based on the dispersion of moisture potential and hydraulic conductivity data within and between series. A 95% prediction interval was constructed to include the range of conductivities to be expected at future sites.
A Branch and Bound Method for use in planning regional wastewater treatment systems
Authors: Downey Brill E. , Nakamura Masahisa
Published: February 2008

A branch and bound method is presented for evaluating alternative regional wastewater treatment systems, taking into account economies of scale in constructing treatment plants and interceptor sewers. A branch and bound tree is ‘grown’ by using an algorithm which is very efficient computationally because it uses a powerful inspection step and a network algorithm to solve subproblems. Each infeasible solution found by using the method is converted to a feasible regional configuration of plants and interceptors. The alternative plans can be compared to examine tradeoffs between cost and other qualitative and quantitative planning objectives. Also the tree itself can be extended to generate additional planning alternatives. Rather than to find mathematically optimal solutions, the principal uses of the method are to generate systematically attractive alternative plans and potentially to assist in evaluating tradeoffs between different planning objectives.
Preservation of the rescaled adjusted range: 2. Simulation studies using Box‐Jenkins Models
Authors: Hipel Keith William , McLeod Angus Ian
Published: February 2008

It is demonstrated that autoregressive moving average (Arma) models do preserve the rescaled adjusted range (RAR) or equivalently the Hurst coefficientK. Arma models are fit to 23 geophysical time series, and by using Monte Carlo techniques and a specified statistical test it is shown that the observed RAR orKis retained by the models. The empirical cumulative distribution function (ECDF) for these statistics can be calculated as closely as is required to the theoretical distribution. Furthermore, the distribution of the RAR is a function of the time series lengthNand the parameter values of the particular Arma process being considered. Various estimates for the Hurst coefficient are compared for the 23 geophysical data sets.

The appendix is available with entire article on microfiche. Order from American Geophysical Union, 1909 K Street, N.W., Washington, D.C. 20006. Document W78‐003; $1.00. Payment must accompany order.
Particulate formation due to freezing humic waters
Authors: Giesy John P. , Briese Linda A.
Published: February 2008

Water samples were collected from a soft water highly humic pond, and all particulates of >0.15‐μm nominal diameter were removed by continuous flow centrifugation. Freezing caused the formation of brown particulates which could be removed by centrifugation. The particulates can be dispersed by sonification, but the size distribution of organic fractions is permanently altered by freezing.
Climate, soil, and vegetation: 2. The distribution of annual precipitation derived from observed storm sequences
Authors: Eagleson Peter S.
Published: February 2008

Point precipitation is represented by Poisson arrivals of rectangular intensity pulses that have random depth and duration. By assuming the storm depths to be independent and identically gamma distributed, the cumulative distribution function for normalized annual precipitation is derived in terms of two parameters of the storm sequence, the mean number of storms per year and the order of the gamma distribution. In comparison with long‐term observations in a subhumid and an arid climate it is demonstrated that when working with only 5 years of storm observations this method tends to improve the estimate of the variance of the distribution of the normalized annual values over that obtained by conventional hydrologic methods which utilize only the observed annual totals.
Climate, soil, and vegetation: 3. A simplified model of soil moisture movement in the liquid phase
Authors: Eagleson Peter S.
Published: February 2008

Natural soil systems are modeled one dimensionally from the surface to a stationary water table by a homogeneous medium defined by three independent parameters. Four varieties of soil moisture movement are analyzed separately, and their effects are linearly superimposed. Infiltration and exfiltration are described by the Philip equation, which assumes the medium to be effectively semiinfinite and the internal soil moisture at the beginning of each storm and interstorm period is assumed to be uniform at its long‐term space‐time average. The exfiltration equation is modified for the presence of natural vegetation through the approximate introduction of a distributed sink representing the moisture extraction by plant roots. Gravitational percolation to groundwater is assumed to be steady throughout the rainy season at a rate determined by the long‐term space‐time average soil moisture. Capillary rise from the water table is assumed to be steady throughout the year and to take place to a dry surface.
Stochastic analysis of spatial variability in subsurface flows: 2. Evaluation and application
Authors: Gutjahr Allan L. , Gelhar Lynn W. , Bakr Adel A. , MacMillan John R.
Published: February 2008

The stochastic differential equation describing one‐dimensional flow in a statistically homogeneous porous medium is solved exactly, and the results are compared with an approximate solution considering small perturbations in the logarithm of the hydraulic conductivity. The results show that the logarithmic approximation is valid when the standard deviation of the natural logarithm of the hydraulic conductivity σf is less than 1; the errors increase rapidly for σf > 1. The effective hydraulic conductivity of statistically homogeneous media with one‐, two‐, and three‐dimensional perturbations is determined to the first order in σf2. The effective conductivity is found to be the harmonic mean for one‐dimensional flow, the geometric mean for two‐dimensional flow, and (1 + σf2/6) times the geometric mean for three‐dimensional flow. The application of stochastic analysis is illustrated through two elementary network design problems that demonstrate the importance of the correlation length of the hydraulic conductivity and the role of measurement error.
The incomplete means estimation procedure applied to flood frequency analysis
Authors: Houghton John C.
Published: February 2008

A new estimation procedure to predict the size Of a design event, given a past flood record, is found to be superior to various alternative fitting procedures. The ‘incomplete means’ method uses no moments higher than the first, a procedure which results in little bias. Although the fitting procedure can be applied to any distribution, it is tested by using a variant of the Wakeby distribution. Using a small Monte Carlo experiment with a single parent distribution, the incomplete means method applied to the logs of the observations results in less regret than other fitting procedures tested. A regret model is developed which introduces a design event based on the density function as an alternative to the more traditional T‐year event.
Geothermal reservoir simulation: 2. Numerical solution techniques for liquid‐ and vapor‐dominated hydrothermal systems
Authors: Faust Charles R. , Mercer James W.
Published: February 2008

Two numerical models are introduced for simulating three‐dimensional, two‐phase fluid flow and heat transport in geothermal reservoirs. The first model is based on a three‐dimensional formulation of the governing equations for geothermal reservoirs. Since the resulting two partial differential equations, posed in terms of fluid pressure and enthalpy, are highly nonlinear and inhomogeneous, they require numerical solution. The three‐dimensional numerical model uses finite difference approximations, with fully implicit Newton‐Raphson treatment of nonlinear terms and a block (vertical slice) successive iterative technique for matrix solution. Newton‐Raphson treatment of nonlinear terms permits the use of large time steps, while the robust iterative matrix method reduces computer execution time and storage for large three‐dimensional problems. An alternative model is derived by partial integration (in the vertical dimension) of the three‐dimensional equations. This second model explicitly assumes vertical equilibrium (gravity segregation) between steam and water and can be applied to reservoirs with good vertical communication. The resulting equations are posed in terms of depth‐averaged pressure and enthalpy and are solved by a two‐dimensional finite difference model that uses a stable sequential solution technique, direct matrix methods, and Newton‐Raphson iteration on accumulation and source terms. The quasi‐three‐dimensional areal model should be used whenever possible, because it significantly reduces computer execution time and storage and it requires less data preparation. The areal model includes effects of an inclined, variable‐thickness reservoir and mass and energy leakage to confining beds. The model works best for thin (<500 m) reservoirs with high permeability. It can also be applied to problems with vertical to horizontal anisotropy when permeability is sufficiently high. Comparisons between finite difference and higher‐order finite, element approximations show some advantage in using finite element techniques for single‐phase problems. In general, for nonlinear two‐phase problems the finite element method requires use of upstream weighting and diagonal lumping of accumulation terms. These lead to lower‐order approximations and tend to obviate any advantage of using the finite element method.
A geomorphic model for use in streamflow routing
Authors: Betson Roger P.
Published: February 2008

Regression equations are presented for predicting parameters in the geomorphic equations that relate Streamflow discharge at a site to channel width and cross‐sectional area (from which velocity and hydraulic depth can be determined). Two measures are used in these regression equations, drainage area and channel slope, both of which are obtained from topographic maps. Regeneration and simulation tests at stream gage sites located in the Cumberland Plateau Physiographic Province indicate that at higher flows this system of equations can predict width and area within ∼25% about ⅔ of the time. These results appear to be comparable with or better than results that would normally be obtained from the reconnaissance field surveys normally used in Streamflow routing for planning‐level applications.
Substituting for water inputs in U.S. manufacturing
Authors: Grebenstein Charles R. , Field Barry C.
Published: February 2008

Partial elasticities of substitution among capital, labor, and water provide empirical evidence concerning the possibilities of adjusting the techniques of manufacturing to accommodate changing scarcities of water. Empirical estimates of elasticities for the United States are obtained by using a trans‐log cost function with SIC two‐digit manufacturing data for 1973. Results show that water and labor inputs are good substitutes but that water and capital are complements. Economic implications of this finding are discussed.
Spatial variability and uncertainty in groundwater flow parameters: A geostatistical approach
Authors: Delhomme J. P.
Published: February 2008

A geostatistical approach is proposed for characterizing the uncertainty about the transmissivity field of an aquifer and analyzing its effect on predicted head values. A new methodology is developed, which couples conditional simulation and groundwater flow modeling. Conditional simulation is used for generating different two‐dimensional transmissivity fields that all have the same spatial variability as the true field and are consistent with the measured T values at well locations. Two case studies are presented in order to illustrate the method, and conclusions are drawn for future investigation.
Effects of channel enlargement by river ice processes on bankfull discharge in Alberta, Canada
Authors: Smith D. G.
Published: February 2008

Results from 24 rivers studied in Alberta show that bankfull recurrence intervals average 16.7 yr, ranging between 2.4 and 45 yr. These results differ sharply from the average of 1.6 yr for rivers in the warmer countries such as Great Britain, Australia, and the United States. The difference in frequency of return period for Alberta rivers may be attributed to channel enlargement caused by the occurrences of scour from ice breakup, drives, and jams of unknown frequencies. The enlarged channel areas (cross sections) at bankfull average 2.6 times larger, but due to comparison adjustments, may be 3 times larger than comparable rivers at bankfull in the United States, and are thus able to carry an average of 4.7 times more discharge, taking into account the increase in velocity.
Preference criterion for flood control under uncertainty
Authors: Krzysztofowicz Roman , Duckstein Lucien
Published: February 2008

Real‐time reservoir control may be reduced to the dual purpose problem of (1) flood control under uncertain inflow and (2) conservation control (water supply, power generation, low flow augmentation, recreation, etc.) after the flood has receded. Under this circumstance, the reservoir flood control is modeled as a game against nature. The decision maker makes the release decisions based upon his value judgments which express preferences over operating attributes and trade‐offs between reservoir purposes and upon his attitude toward risk. His decision behavior is described by a two‐attribute disutility function. It is argued that minimization of expected disutility is a plausible and well motivated criterion for reservoir flood control under uncertainty. Problems of application are discussed, and an experiment in assessing the disutility functions of individuals is reported.
Thermal alteration of groundwater caused by seepage from a cooling lake
Authors: Andrews Charles B. , Anderson Mary P.
Published: February 2008

Groundwater temperatures in the vicinity of a 200‐ha power plant cooling lake in central Wisconsin were monitored in the field for 1 year, and the response of subsurface temperatures to seasonal changes in lake and air temperatures was simulated by means of a mathematical model. The cooling lake, which has been in use since May 1975, when a 500‐mw electric generating unit began operation, loses water to the groundwater system at a rate of 2 × 104m3/d. The zone of thermally altered groundwater is confined to a relatively small area hydraulically downgradient from the cooling lake. However, the lake is situated in a groundwater discharge area, and changes in subsurface temperatures at depths less than 6 m are believed to have affected the vegetation in the thermally altered zone. The model, which couples equations describing groundwater flow with those describing heat transport in the subsurface, was used to simulate the seasonal temperature fluctuations within seven cross sections oriented parallel to the direction of groundwater flow away from the cooling lake. Simulated temperature patterns agreed well with field data but were very sensitive to the distribution of subsurface lithologies. Results from a predictive simulation suggest that when a second 500‐mw generating unit begins operation in 1978, groundwater temperatures will increase less than 5°C at distances greater than 15 m from the cooling lake. The results of this study suggest that the potential for significant thermal alteration of surface water bodies located in groundwater discharge areas is slight.
Modeling phytoplankton dynamics using catastrophe theory
Authors: Duckstein Lucien , Casti John , Kempf James
Published: February 2008

The use of catastrophe theory to obtain a predictive model of the eutrophication phenomenon is examined and applied to the case of small, highly eutrophic ponds or embayments in large water bodies. Phytoplankton dynamics is represented by a non‐linear differential equation derived on the basis of phenomenological considerations. This equation can be reduced analytically to the canonical form for a cusp catastrophe model. Numerical integration of the dynamics equation is calibrated with data taken during a phytoplankton bloom in small ponds by Parks et al. (1975). The model trajectory matches closely the data for both Anabaena concentrations and total algae concentration; however, model trajectory for a third variable, solution phosphate concentration, appears to match laboratory data rather than field observations. Implications for fish pond management are given, and possible use of the catastrophe theory approach to model algal succession is discussed.
The sensitivity of reservoir returns to the availability of design data
Authors: Cornish Brian A.
Published: February 2008

When an irrigation system is designed to maximize the economic return from the system, the final design depends to a large extent on the values of the statistical parameters of the inflows into the system. In all practical situations these statistical parameters are not known with certainty but are estimated from the available historical record of the flows. A simulation technique has been devised to determine the sensitivity of the economic return from an irrigation system to various lengths of historical flow records when the criterion of the design is to maximize the economic return. The simulation model has also been used to find the sensitivity of the returns to changes in various other system parameters.
Multiobjective optimization in river basin development
Authors: Duckstein Lucien , Opricovic Serafim
Published: February 2008

Multiobjective optimization in water resources planning consists in trading off noncommensurable objectives within the framework of a complex and dynamic process. Multiobjective optimization is performed at two levels: first, an engineering level, which may be labeled a decision‐making aid phase; and then, a managerial level of acceptance of the solution. The engineering level optimization may be performed by means of a cost‐effectiveness approach followed by the application of compromise programing, which consists of choosing a compromise solution located as close as possible to an ideal but non‐feasible solution. In this paper this combined method is applied to the design of a water resources system in the Central Tisza River Basin in Hungary. The results obtained by following this approach are compared to those in David and Duckstein (1976) and Keeney and Wood (1977), who used, respectively ELECTRE and multiattribute utility theory instead of compromise programing to study the same basin. The proposed methodology is able to lead to either one of the two different decisions resulting from the other studies. A brief discussion of possible approaches for final choice of alternative system is given. Key words in this paper are multiobjective optimization, decision‐making aid, cost‐effectiveness approach, compromise programing, and river basin development.
Fitting log normal distributions to hydrologic data
Authors: Stedinger J. R.
Published: February 2008

The mean square error of estimation of selected quantities is used to evaluate the efficiency of alternative methods for fitting the two‐ and three‐parameter log normal distributions. Monte Carlo results show that use of maximum likelihood parameter estimation dominates other methods for fitting the two‐parameter log normal distribution for samples of 25 or more log normal variates. For the three‐parameter log normal distribution the standard moment method performs best for log normal distributions with low skew coefficients, while use of the sample mean, variance, and quantile estimate of the lower bound performs better for highly skewed log normal distributions; use of the unbiased standard deviation and skew coefficient is almost dominated by this new fitting procedure. The performance of the better fitting procedures is also evaluated when the observations are drawn from a log Pearson type 3 distribution.
An event‐based model of recharge from an ephemeral stream
Authors: Flug M. , Abi‐Ghanem G. V. , Duckstein L.
Published: February 2008

Estimating annual recharge is an important input to the management of groundwater resources. Available hydrologic information is used to derive a model‐based prior distribution function of annual recharge from an ephemeral stream. To illustrate the methodology, a linear transfer model defining groundwater recharge as a function of streamflow is postulated from stream characteristics in arid lands. Parameters of the groundwater model are identified by using streamflow data as input and recharge data as output. The parameters are then used in an event‐based approach to determine the distribution function for annual recharge. The model is applied to the Rillito Creek, a part of the Tucson alluvial basin, Arizona. The method, however, is applicable to other areas, can incorporate more sophisticated transfer functions, and may be extended to include larger watersheds consisting of multiple reaches.
Cost‐efficiency of transferable discharge permits for the control of BOD discharges
Authors: Eheart J. Wayland
Published: February 2008

The cost efficiencies of four systems of transferable discharge permits (TDP's) designed for BOD control were compared to least‐cost and minimum uniform treatment strategies for achieving the same water quality. One of the four policies, viz., the policy in which the permits are defined in terms of the dissolved oxygen deficit contribution (DODC) at the checkpoint, always induces a least‐cost treatment strategy. Another policy, for which the permits were defined in terms of the discharge rate (load) of ultimate BOD, is almost as efficient as the least‐cost strategy for the example case of the Willamette River. The requirements for the high cost efficiency of the latter policy are identified, analyzed, and discussed. The economic cost for all four policies, some of which were very conservative, was found to lie between the least cost and the cost of minimum uniform treatment.
Instability in aquifer identification: Theory and case studies
Authors: Yakowitz Sidney , Duckstein Lucien
Published: February 2008

It is our conviction that we and other investigators have in the past not been fully cognizant of how troublesome measurement noise can be to aquifer identification methods. In the present work we set forth theoretical reasons why one may anticipate that the aquifer identification problem can be numerically unstable. This insight is underscored by numerical demonstration showing that under certain realistic assumptions concerning aquifer parameters and measurement error, transmissivity estimates provided by certain sensible identification schemes are seriously in error. By examination of the insensitivity of piezometric head to change in transmissivity we suggest that the numerical instability is fundamental to certain aquifer identification problems; it cannot be overcome by finding the ‘right’ identification method, just exacerbated by poor methods. This work provides procedures whereby other investigators can perform error and sensitivity analysis on their aquifer configurations and identification algorithms.
Modeling groundwater flow over sloping beds
Authors: Chapman T. G.
Published: February 2008

A new approximation for two‐dimensional Dupuit‐Forchheimer flow of groundwater over a sloping bed is shown to be acceptable up to slope angles of at least 30°, when compared with known results for two steady flow situations. The approximation is suitable for three‐dimensional numerical modeling and is recommended for situations in which the flow pattern is controlled by the bed slope.
Osmotic model to explain anomalous hydraulic heads
Authors: Marine I. Wendell , Fritz Steven J.
Published: February 2008

Laboratory experiments have shown that compacted clays act as osmotic membranes when they separate aqueous solutions of unequal ionic concentration. Theoretically, osmotically induced differential hydraulic pressure in groundwater systems can be relatively high. The magnitude depends primarily upon concentration differences across the membrane, type of ions, type of clay, and pore size. In experiments, thin, compacted clay membranes commonly exhibit varying degrees of osmotic efficiency due to ion leak‐age through the clay. In natural systems the membrane and the solution containers are not as distinct and well defined as they are in the laboratory. Moreover, the membrane is commonly thick, inhomogeneous, and composite. In a buried Triassic basin at the Savannah River plant near Aiken, South Carolina, it is suspected that osmosis causes the saline water in the basin center to be slightly geopressurized in relation to freshwater in the overlying coastal plain aquifer. Two wells have heads of 7.88 and 12.98 bars (114.3 and 188.3 psi) above the head in the coastal plain aquifer. The head in each of these wells approximates the osmotic equilibrium head calculated from solution concentration of water produced by each well (12,000 and 18,500 mg/l, respectively). Other wells penetrating the top and edge of the Triassic basin probably penetrate a zone where ion leakage gives rise to less saline water. Thus these wells are not geopressurized.
Estimating correlations in multivariate streamflow models
Authors: Stedinger Jery R.
Published: February 2008

Multivariate log normal distributions are often used to model and generate multisite and multiseason streamflow sequences. A Monte Carlo study evaluated alternative estimators of the cross correlation between autocorrelated streamflow series and the lag 1 autocorrelation of a single series when some or all of the flows have a log normal distribution. Generally, smaller mean square error estimates of the correlations of flows are obtained by using the variances and covariances of the flow's logarithms to estimate a streamflow model's parameters. Sometimes it is advantageous to prewhiten two series before calculating their cross correlation and to unbias the estimated autocorrelation of the streamflow's logarithms.
Methods for estimating the number of identifiable organic pollutants in the aquatic environment
Authors: Janardan Konanur G. , Schaeffer David J.
Published: February 2008

Shackelford and Keith (1976) have compiled data on the organic compounds which have been identified in water. A complex sample consists of a large number of distinct compounds. Of the compounds potentially identifiable by a given method, some are actually identified. Methods for estimating the number of additional compounds which could have been identified are presented. These data are used to provide estimates of the number of observed compounds (350) which are expected to appear in a similar list developed from nonoverlapping sources. The expected number of unobserved (but observable) compounds (about 1200) which could be identified using techniques comparable to those giving rise to the data in Shackelford and Keith's list is obtained. These methods are then used to determine if the rate at which we are identifying new compounds (in a deliberate search for new compounds) is greater than the rate determined from Shackelford and Keith's data base.
A set of equations for full spectrum and 8‐ to 14‐μm and 10.5‐ to 12.5‐μm thermal radiation from cloudless skies
Authors: Idso Sherwood B.
Published: February 2008

A comprehensive experiment was conducted at Phoenix, Arizona, involving the monitoring of full spectrum thermal radiation and those fractions of that flux that are contained within the 8‐ to 14‐μm and 10.5‐ to 12.5‐μm subrogions. Also monitored were surface air temperature (T0) and vapor pressure (e0). Analyses of the data established the source of water vapor associated thermal emittance (ϵ) variations of the cloudless sky as being due to the variable atmospheric concentration of water dimers—pairs of water molecules linked together by weak hydrogen bonds. New equations ((15)–(17)) based on this physical model were thus developed for the effective emittance of the atmosphere in both the 10.5‐ to 12.5‐µm and 8‐ to 14‐μm wavebands, as well as for the full thermal spectrum. Equation (17) was then shown to be a significant improvement over previous equations that have attempted to model this phenomenon.
Diffusion and sorption in particles and two‐dimensional dispersion in a porous medium
Authors: Rasmuson Anders
Published: February 2008

A solution of the two‐dimensional differential equation of dispersion from a disk source, coupled with a differential equation of diffusion and sorption in particles, is developed. The solution is obtained by the successive use of the Laplace and the Hankel transforms and is given in the form of an infinite double integral. If the lateral dispersion is negligible, the solution is shown to simplify to a solution presented earlier. Dimensionless quantities are introduced. A steady state condition is obtained after long times. This is investigated in some detail. An expression is derived for the highest concentration which may be expected at a point in space. An important relation is obtained when longitudinal dispersion is neglected. The solution for any value of the lateral dispersion coefficient and radial distance from the source is then obtained by simple multiplication of a solution for no lateral dispersion with the steady state value. A method for integrating the infinite double integral is given. Some typical examples are shown.
mass transport: 2. Analysis of uncertainty in prediction
Authors: Smith Leslie , Schwartz Franklin W.
Published: February 2008

The first paper in this series presented a description of a stochastic modeling concept for mass transport. In this paper we extend that analysis to consider a more realistic set of transport conditions in a groundwater basin with geologic layering, hydraulic anisotropy, spatial variations in porosity, and geochemical retardation. Uncertainties in transport predictions can be characterized by frequency distributions formed on the time of arrival of mass at the water table, on the exit location, and on the quantity of mass arriving at the water table as a function of time. Results show that transport is highly sensitive to porous medium heterogeneities. Considerable uncertainty is possible in predicting the spatial and temporal distribution of mass. Porous medium parameters capable of changing both the magnitude and direction of advective transport are of primary importance in influencing predictive ability. Most important in this respect are the arrangement of units with different mean hydraulic conductivities, the standard deviation and spatial continuity of hydraulic conductivity, and the hydraulic anisotropy. In certain geologic systems, patterns of contaminant migration can be predicted with more certainty. Features such as layering and hydraulic anisotropism can constrain the flow of mass to specific directions, thus limiting the size of the region through which mass is likely to spread. Depending upon the relative time scales of the release function and the transport process, lack of information about the timing and concentrations added at the source may cause greater uncertainty than the heterogeneity.
Evaluation of underutilized resources in water resource development
Authors: Chalmers James A. , Threadgill J. Randall
Published: February 2008

Existence of underutilized resources has been recognized as important in the evaluation of the economic cost of water resource development projects. Recent concern with socioeconomic impact during project construction has reemphasized the importance of the level of local resource utilization in project assessment procedures. This paper surveys the consideration of underutilized resources in the economics literature, reviews several empirical attempts to measure the importance of the phenomenon, and develops a conceptual framework within which to examine the issue. The proposed conceptual framework provides guidance in interpreting existing empirical work and identifies promising lines of future research.
Analyzing floodplain policies using an interdependent land use allocation model
Authors: Hopkins Lewis D. , Brill E. Downey , Kurtz Kenneth B. , Wenzel Harry G.
Published: February 2008

A model is described that compares allocations of land uses in terms of aggregate economic rent, taking specific account of the interdependence between floodplain land uses and upstream land uses. Solution of this model by dynamic programming for the Hickory Creek watershed suggests that some restriction of land uses in the floodplain, but not for all subbasins, and some provision of detention, but not for all subbasins, is preferable to the results likely from implementation of typical policies for floodplain management. Determination of target land use patterns through allocation models that account for the interdependence may therefore be worthwhile if policy instruments can be developed so that such targets can be attained.
Community evaluation of adopted uses of reclaimed water
Authors: Bruvold William H.
Published: February 2008

One hundred and forty residents of Irvine, California, were interviewed to assess their knowledge, evaluation, and recommendations regarding the use of reclaimed water in their community for an ornamental lake, for golf course irrigation, for agricultural irrigation, for park and playground irrigation, and for common residential lawn irrigation. Additionally, their attitudes toward future use of reclaimed water for drinking, not presently planned for Irvine, were also assessed. Results showed that more than half of the respondents were generally aware of reclamation in Irvine, but more than half were not aware of the details involved. Once specific uses were outlined for the less informed, the responses of all respondents to the specific reclamation and reuse projects now underway in Irvine were very positive. Most respondents recommended continuing existing uses rather than expanding or reducing the current reclamation project. Furthermore, most respondents were not in favor of using reclaimed water for drinking in the future. The Irvine findings confirm earlier, more general findings that indicated that the public will accept moderate contact uses of reclaimed water in their own community, and it is recommended that reclamation projects be initiated in this manner.