bluuebunny/crossref_metadata_2025 huggingface dataset:
Position of the saline water interface beneath oceanic islands
Authors: Fetter C. W.
Published: February 2008

If saline and fresh groundwater are assumed to be immiscible, the three‐dimensional position of the saline water interface beneath an oceanic island may be described by one partial differential equation. The Dupuit assumption is used so that the governing flow equation is two‐dimensional. Analytical solutions are presented for islands with certain simple geometric boundaries. Multilayered aquifers may be treated by assuming an average conductivity for all aquifer layers. The model may be solved for islands of any shape by using a numerical solution. The model has been used successfully to generate the known position of the saline water interface beneath the South Fork of Long Island, New York, and could be used in water resource studies to determine the position of the saline water interface if it were unknown.
Factor analysis of shoreline physiography and perception of water level drawdown by reservoir shoreline residents
Authors: Jaakson Reiner
Published: February 2008

Factor analysis is used to examine the relationship between variations in shoreline physiography and perception of water level fluctuation by reservoir recreation users. Three elements of perception are examined: frequency of objection to water level fluctuation, frequency with which users feel that recreation enjoyment is reduced by water level fluctuation, and, as an element that may reflect perception, user days of recreation. A test of the relationship between factors and water level fluctuation is made by correlating factor scores with storage capacity on 11 reservoirs and three control lakes. Five factors are identified and evaluated in terms of their significance to recreation.
Acoustic properties of frozen Ottawa sand
Authors: Nakano Yoshisuke , Arnold Robert
Published: February 2008

Ultrasonic velocities of dilatational and shear waves as well as damping of dilatational waves in frozen Ottawa sand were measured as a function of water content by using the critical angle method at a frequency of 1 MHz. The dilatational velocity was found to vary with increasing water content from about 0.35 km/sec to 4.6 km/sec. The shear velocity also increases monotonically with increasing water content. The results of damping measurements showed a general trend for the quality factor Q to decrease monotonically with decreasing water content.
Component sensitivity: A tool for the analysis of complex water resource systems
Authors: McCuen Richard H.
Published: February 2008

The value of sensitivity estimates for determining an optimal set of model parameters has been recognized for over a century. However, the inadequacy of the mathematical foundation of sensitivity has prevented the use of systematic gradient optimization techniques for the analysis of complex water resource systems and hydrologie simulation models. The computer time required to increment each parameter and to measure the change in output is considered excessive for optimization of complex systems. The use of component sensitivity provides an alternative to the method of parameter perturbation that greatly reduces the computational effort. The mathematical foundation of component sensitivity is introduced, and the method of computation is demonstrated for a two‐component system. However, the mathematical foundation of component sensitivity is easily extended to more complex systems.
Water quality perception and the recreational uses of Green Bay, Lake Michigan
Authors: Ditton Robert B. , Goodale Thomas L.
Published: February 2008

How people perceive Green Bay as a recreation resource, how perceptions differed between groups, and how these perceptions related to recreation use patterns, are identified. Whereas seven of 10 household heads interviewed participated in boating, or swimming, only three of the 10 used Green Bay during the preceding 12 months, indicating that Green Bay was not a focal point of water‐based recreation among residents of the five‐county study area. Chi square test groups differed significantly on most comparisons when used to describe the Bay and its most bothersome physical and water quality characteristics. Generally, participants and those who use the Bay were less apt to cite unpleasant smell and dead fish as major problems and more apt to cite such problems as winds, waves, and cloudiness. Comparisons between three user groups (fishermen, boaters, and swimmers) indicated swimmers and boaters differed most in their perception of the Bay and its troublesome characteristics, with fishermen occupying a position between the two groups.
National and interregional models of water demand, land use, and agricultural policies
Authors: Heady Earl O. , Madsen Howard C. , Nicol Kenneth J. , Hargrove Stanley H.
Published: February 2008

This national study deals with the optimum allocation of land and water resources in 223 agricultural‐producing or land regions, 51 water supply regions, and 27 market regions of the United States. It analyzes these questions: Will the nation be able to meet its urban and industrial needs for water in the year 2000? Will these allocations require a smaller or redistributed use of water in agriculture? To what extent can land be substituted for irrigation water in attaining the nation's domestic and export food demands? From which crops and regions should water be diverted in attaining an efficient agriculture and in meeting non‐agricultural uses of water? The study is based on programing models of 3220 equations (including 1650 fixed bounds) and 5426 real variables in the framework of interregional competition and comparative advantage. It estimates the extent to which land could be substituted for water and vice versa in an efficient future use of resources. Jt indicates where and to what extent water should be reallocated among areas of agriculture and between agricultural, urban, and industrial uses. It analyzes the impacts of alternative futures on the demand for water. Alternatives examined are those of water prices, population levels, farming technology, export quantities, and agricultural policies. In general, the results show that, if agricultural and water development policies were changed over the future, the nation would not be faced with an overall water scarcity, and even surplus food producing capacity could exist with the use of less water for agricultural purposes.
Multiobjective screening models and water resource investment
Authors: Cohon Jared L. , Marks David H.
Published: February 2008

A case study of a river system is presented in which development is to be planned according to national and regional objectives. A linear screening model for finding the best set of development alternatives from a national objective point of view is introduced and a brief discussion of methods for handling more than one objective in such models is presented. An analysis of the trade offs between the two objectives is demonstrated by using a constraint method. The transformation curve between net national income benefits from power and irrigation and regional equity as measured by deviation from an equal regional water distribution is shown.
Application of a simple hydrologic model for rainfall‐runoff relations of the Dalton Watershed
Authors: Diskin M. H. , Buras N. , Zamir S.
Published: February 2008

The problem of determining the best operating policy for a small storage reservoir or pond was solved by means of a simulation model based on a simple conceptual hydrologic model developed for rainfall‐runoff relations for the watershed contributing to the pond. The hydrologic model is represented by a single element described by one parameter and having only one state variable. The simple model was found to give an adequate representation of the watershed for the particular problem for which it was used.
Effect of solute dispersion on thermal convection in a porous medium layer
Authors: Rubin Hillel
Published: February 2008

Thermal convection and overstable motions may sometimes play an important role in salt diffusion in an aquifer. In such cases hot saline water is in the deep layers of the aquifer, from which salt diffuses into the upper freshwater. Often the horizontal steady flow of the water in the aquifer increases the rate of diffusion of soluted materials. Salt diffusion is then characterized by the anisotropic dispersion tensor. The effects of salt dispersion by the steady state flow in the aquifer were examined in connection with the thermal stability of the flow field. It was found that dispersion of the soluted material reduces the stabilizing effect of the salinity profile but increases the stability of the flow field to pure overstable motions. Dispersion also changes the dimensions of Bénard cells in the porous medium. The dispersion tensor fluctuations hardly affect the stability criteria of the flow field but cause very small overstable motions that distort the shape of the convective current cells.
Equation for one‐dimensional vertical flow of groundwater: 1. The Rigorous Theory
Authors: Gambolati Giuseppe
Published: February 2008

A new mathematical derivation of the one‐dimensional flow equation in an elastic, saturated, porous medium is presented. The approach involving the consideration of a fixed elemental volume in fixed coordinates is developed by starting from both Lagrangian and Eulerian definitions of the position vector. The confusion existing about these two fundamental points of view has so far led to theoretically erroneous results. The Lagrangian and Eulerian formulations prove to be equivalent and provide the same outcome if they are correctly interpreted and consistently applied. The rigorous equation, compared with Cooper's (1966) equation, turns out to contain an additional nonlinearity resulting from the correct expansion of the partial spatial derivative of the grain velocity. It is also shown that an approach based on a deforming element in fixed coordinates is simple and straightforward, since it does not introduce the grain velocity into the development. However, it needs a particular definition for the compressibility different from the classical one. It is proved that these two compressibilities are not equal; their mathematical link is derived.
Residential water demand: The case from micro data
Authors: Morgan W. Douglas
Published: February 2008

A cross section demand function for water is estimated using individual residential dwelling units as the sample. Both assessed value of property and number of persons per dwelling are significant determinates of the quantity of water demanded consistent with the theoretical development. Moreover, it is concluded that there are economies of scale of water use with respect to household size.
A dynamic programing‐simulation strategy for the capacity expansion of hydroelectric power systems
Authors: Kuiper John , Ortolano Leonard
Published: February 2008

The capacity expansion of a mixed hydrothermal power system is analyzed by means of dynamic programing to compare alternative sequences of power development and by means of a fast running, approximate simulation model to evaluate the operation of possible power system states in the dynamic programing model. Because the simulation of all states in the dynamic programing model is too time consuming, only selected states are simulated, and these states are identified by using an iterative solution procedure. The resulting ‘dynamic programing‐simulation strategy’ is applied to the preliminary planning of the expansion of a mixed hydrothermal power system in Brazil. The solution procedure is computationally efficient and leads to a substantial reduction in the estimated cost of a future sequence of power development.
The role of rainfall impact in soil detachment and transport
Authors: Young R. A. , Wiersma J. L.
Published: February 2008

The relative importance of raindrop impact and flowing water to the erosion process was determined in a laboratory study using three soils, loam, silt loam, and sandy loam, prepared with preformed rills and subjected to simulated rainfall. The source and the mode of transport were determined for all soil detached and transported from the plot under conditions of both normal rainfall energy and greatly reduced rainfall energy. Decreasing rainfall impact energy by 89% without reducing rainfall intensity decreased soil losses by 90% or more, and it was thus indicated that the impact energy of raindrops is the major force initiating soil detachpent. For all three soils, 80–85% of the soil loss originating in the area between the rills was transported to a rill before leaving the plot, and it was thus indicated that the transport of detached particles from the plot was accomplished mainly by rill flow.
Groundwater basin studies through the electronic circuit analysis program on the digital computer
Authors: Thomas Robert G.
Published: February 2008

The electronic circuit analysis program was developed by the electronics industry to solve complex electronic circuit problems on digital computers. The program is directly applicable to groundwater models of relatively small size and may be used by anyone who is not familiar with computer programing but who is familiar with electrical circuits and, particularly, resistor‐capacitor groundwater models. Both steady state and transient solutions are possible, and a wide variety of the usual groundwater conditions can be easily studied.
Optimal Design and Operation of Water Distribution Systems
Authors: Shamir Uri
Published: February 2008

A methodology is developed for optimal design and/or operation of a water distribution system that is to operate under one or several loading conditions. Decision variables may be design variables, such as pipe diameters, or control variables, such as heads and flows. The objective function may include the initial cost of the design, the cost of operation, the physical measures of performance, and the penalties for violating constraints. Constraints may be imposed on the decision variables and on the performance of the system under each loading. Flow solutions are obtained by a modified Newton‐Raphson method employing sparse matrix techniques. Optimization is obtained by a combination of the generalized reduced gradient and penalty methods. Implementation in a computer program and its use on a test problem in both batch and time‐sharing modes are described, and it is concluded that the method is computationally feasible. The many different ways in which it can be used to analyze, design, and operate water distribution systems are outlined.
Effects of Salt Concentration Changes During Freezing on the Unfrozen Water Content of Porous Materials
Authors: Banin Amos , Anderson Duwayne M.
Published: February 2008

By combining equations for salt concentration by water removal from porous bodies with those for freezing point depression in normal solutions, equations are developed for calculating freezing point depression shifts due to the gradual removal of water upon freezing in porous bodies. The same equations can be used for the calculation of shifts in the osmotic potential of the water in drying porous bodies by using a simple conversion factor. Graphs relating the remaining water content to the freezing point shift for various initial soluble salt contents are given. Good agreement is found between the measured freezing point depression shifts for a silty clay soil treated with three concentrations of sodium chloride and with dimethyl sulfoxide at various contents of unfrozen water and the calculated values. The order of magnitude of the shifts expected in various natural conditions is discussed.
Economic damages from residential use of mineralized water supply
Authors: Tihansky Dennis P.
Published: February 2008

Household appliances and personal items in contact with water supplied municipally or from private sources are subject to physical damages from chemical and other constituents of the water. This study translates these damages into economic losses for a typical household. Then it aggregates these losses at the national and individual state levels. To do so required several stages of analysis. First, the types of physical damages expected and the associated water quality determinants were identified, and the physical effects were then translated into economic losses. Second, damage functions were formulated to predict likely impacts of water quality changes on each household unit affected. Third, a computer program based on these functions was designed to estimate total damages per typical household and to aggregate them over selected regions. Finally, the program was applied to state‐by‐state data describing water supply sources and socioeconomic parameters. Total annual damages to U.S. residents in 1970 were estimated to be in the range $0.65–$3.45 billion, the mean being $1.75 billion. The mean translates to $8.60 per person annually. States having the highest total damages were California ($230 million) and Illinois ($164 million). On a per capita basis, Arizona ($22.53) and New Mexico ($18.58) ranked highest, whereas South Carolina ($1.15) and Oregon ($1.73) were at the other end of the spectrum. When per capita damages were compared by source of water supply, private wells were highest at an average of $12.34, treated groundwater was next at $11.20, and treated surface water was last at only $5.83.
Effect of grazing on runoff from two small watersheds in southwestern Wisconsin
Authors: Sartz Richard S. , Tolsted David N.
Published: February 2008

Storm runoff from two small open pasture watersheds was measured for 11 years: during the first 7 years both were grazed, and during the last 4 years only one was grazed. Their runoff behavior was similar when both were grazed, but by the third year after cessation of grazing, runoff from the ungrazed watershed had dropped sharply. The ungrazed/grazed ratio for mean total flow had dropped from 1.17 to 0.10 and for mean peak flow from 0.82 to 0.03. After 3 years without grazing a heavy mat of bluegrass blanketed the ground, and soil bulk density was significantly lower.
The long‐run asymmetry of subsidies and taxes as antipollution policies
Authors: Porter Richard C.
Published: February 2008

Primers on the discharge of unwanted but unpriced effluents into the air and water now treat as a commonplace the symmetry between taxes (or charges) on effluents and subsidies (or bribes) for abatement as means of reducing an industry's pollution. This note shows that, on the contrary, serious asymmetry results when entry and exit occur in response to subsidies or taxes. Not only does the quantitative symmetry disappear, but even the qualitative impact (i.e., the directions of the effects) of charges and bribes on the volume of firm and industry effluents may differ. More specifically, the possibility emerges that an abatement subsidy offered to an industry may increase the total effluents of that industry.
Multivariate generation of mixtures of normal and log normal variables
Authors: Mejía José M. , Rodríguez‐Iturbe Ignacio , Cordova José R.
Published: February 2008

The generation of processes formed by mixtures of normal and log normal variables is investigated. The transformations required to preserve the statistics of a historical sample are presented. The results are illustrated by an application to a specific model.
Decision analysis of a gamma hydrologic variate
Authors: Yakowitz Sidney , Duckstein Lucien , Kisiel Chester
Published: February 2008

Hydrologists have studied the statistical nature of summer‐type storms and the decision problems associated with containing their runoff. In this tradition, winter storms are examined here. In contrast to summer storms the gamma family rather than the exponential fits the Tucson rainfall record. Use of the gamma law entails greatly increased computational complexity, and a major effort is made to achieve efficiency of calculation. This study begins by reporting statistical tests indicating that the gamma family describes the precipitation process. A natural conjugate family for the gamma law is derived and discussed. Numerical methods for Bayesian analysis of the (somewhat recalcitrant) gamma variate are explained and tested on simulated data. The concluding sections give examples (return time and levee height) of decision making when the gamma family is the underlying law. The method of decision analysis is applicable to other hydrologic problems in which the gamma distribution (also called the Pearson type 3) is a plausible model. Moreover, it is believed that the bulk of the numerical methods derived herein will prove useful in significantly many other Bayesian decision theory contexts.
The design of rainfall networks in time and space
Authors: Rodríguez‐Iturbe Ignacio , Mejía José M.
Published: February 2008

A methodology for the design of precipitation networks is formulated. The network problem is discussed in its general conception, and then focus is made on networks to provide background information for the design of more specific gaging systems. The rainfall process is described in terms of its correlation structure in time and space. A general framework is developed to estimate the variance of the sample long‐term mean areal precipitation and mean areal rainfall of a storm event. The variance is expressed as a function of correlation in time, correlation in space, length of operation of the network, and geometry of the gaging array. The trade of time versus space is quantitatively developed, and realistic examples are worked out showing the influence of the network design scheme on the variance of the estimated values.
Accuracy of precipitation measurements for hydrologic modeling
Authors: Larson Lee W. , Peck Eugene L.
Published: February 2008

The use of precipitation data as input for conceptual hydrologic models has enhanced the need for measurements more representative of ‘true’ precipitation. Precipitation input to continuous watershed models is generally some form of mean basin precipitation estimate based on point measurements. Each point measurement can have large catch deficiencies due to wind, especially for solid precipitation. A brief review is made of past results from studies concerned with these deficiencies. New curves based on current studies are presented for wind‐caused gage catch deficiencies for both rain and snow. The results of using gage catch correction factors to adjust precipitation input to a conceptual hydrologic model are presented.
Stream gradient as a function of order, magnitude, and discharge
Authors: Flint J. J.
Published: February 2008

The downstream change in the average channel gradient derived from order data can be expressed in terms of either area or discharge in the form of a power function. Similarly, the average channel profile based on link slope can be related to link magnitude or discharge in the form of a power equation. Finally, from the downstream hydraulic geometry equation the change in stream gradient can be expressed in terms of discharge or area as a power function. Because these relations are identical in form and in their independent parameters, rates of change in slope obtained by all three approaches should be equivalent. The rates of change in stream gradient derived from the power functions above yield almost identical averages for entire channel networks. The order data give a rate of −0.63, whereas link slope exponents average −0.60. These values are well within the range of variation for published data obtained for the hydraulic geometry equation (averages between −0.49 and 0.95) and may represent a quasi‐equilibrium tendency for entire fluvial systems.
A predictor‐corrector method for solving the convection‐dispersion equation for adsorption in porous media
Authors: Tagamets T. , Sternberg Y. M.
Published: February 2008

The one‐dimensional convection‐dispersion equation subject to a nonlinear adsorption isotherm is formulated and solved by using a predictor‐corrector finite difference scheme. The effects of convection, dispersion, and adsorption are illustrated for some typical values of variables encountered in ‘real systems.’ A comparison between the numerical results and some experimental data is also presented.
Energy budget measurements over three cover types in eastern Arizona
Authors: Thompson J. R.
Published: February 2008

Three years of continuous records of net radiation Rn were taken over a pine forest, a cienega, and a clear‐cut opening. Seasonal patterns of the portion of Rn going into evapotranspiration ET were determined for these cover types by energy budget measurements in the Bowen ratio equation. By using the average daily Rn over two summer periods (May to June and July to September) and the mean ratios of ET to Rn, ET for the three cover types for the growing season was estimated at 19.4 in. for the forest, 15.3 in. for the clear‐cut opening and 13.2 in. for the cienega. Weighting these amounts by the extent of the type resulted in a watershed average ET of 18.4 in. for the growing season.
Analyzing reimbursement mechanisms for resource development projects
Authors: Dobbs Thomas L. , Huff Charles E.
Published: February 2008

A procedure for analyzing reimbursement mechanisms for natural resource development projects is presented and applied to a case study of a proposed water transfer project in Wyoming. The analytic framework presented consists of an impact matrix and a reimbursement matrix. Efficiency, equity, revenue‐raising ability, and administrative feasibility criteria are utilized to assess the reimbursement mechanisms in light of information displayed in the two matrices. Application of the analytic framework to the case study indicates its usefulness to state and regional planners responsible for project financing and reimbursement analyses. By utilizing separate impact and reimbursement matrices the framework described helps to distinguish between impacts of a project on groups within a region and how those groups might share in or be reimbursed for project and related costs. Also in contrast to conventional repayment analyses focusing primarily on user charges the framework permits consideration of a wide range of reimbursement mechanisms.
Deep snow measurements suggested using cosmic radiation
Authors: Bissell Vernon C. , Burson Zolin G.
Published: February 2008

The attenuation of highly penetrating cosmic radiation shows promise as a means of measuring the water equivalent of snow cover. The attenuation of cosmic radiation by water is sufficient to make the method practicable, especially for deep snow. As an example, statistical counting errors in a two‐detector setup (using 10 cm by 10 cm Nal(Tl) scintillation detectors, one above the snow and one beneath the snow) would produce a water equivalent measurement accuracy of better than 1% in measuring 100 cm of water with a 24‐hour measurement time.
Use of axisymmetric infiltration model and field data to determine hydraulic properties of soils
Authors: Jeppson Roland W. , Rawls Walter J. , Hamon W. Russell , Schreiber David L.
Published: February 2008

A numerical model is described for solving axisymmetric infiltration problems. The model uses saturation‐capillary pressure data and a modified Burdine equation to develop reasonable estimates of relative hydraulic conductivity. A specially designed infiltrometer and a field data collection system, which provide infiltration capacity, saturation‐time, and saturation‐capillary pressure data, are also described. The numerical solutions were fitted to the field data to define the hydraulic properties of the soil. Close agreement was found between the numerical model solutions and the field measurements for two sites on the Reynolds Creek Experimental Watershed in southwestern Idaho. A feasible method was developed for determining the hydraulic properties of surface soils under natural conditions.
New equations for determining the formation constants of an aquifer from pumping test data
Authors: Boulton Norman S. , Streltsova Tatiana D.
Published: February 2008

New equations are given, based on an extended theory, that take into account the following factors: the compressibility and anisotropy of the main aquifer; the partial penetration of the abstraction well; the depth at which the drawdown in an observation well is measured; the existence of a low‐permeability layer, hereafter called ‘the aquitard,’ above the aquifer; and the saturated and unsaturated zones above the water table. A practical method of evaluating the formation constants for an aquifer from pumping test data is fully discussed. Type curves based on the new equations are used to analyze data from a pumping test in the thick Bunter sandstone formation of Shropshire (Great Britain). A correction for the water derived from storage within the abstraction well is found to be necessary.
A general linear approach to stream water quality modeling
Authors: Arbabi Mansur , Elzinga Jack
Published: February 2008

The problem of meeting stream dissolved oxygen standards while optimizing some objective is treated. New properties of the oxygen sag equation allow the constraint set of such mathematical programs to be described to a high degree of accuracy by linear inequalities; except for upper and lower bounds on pollutant discharges, three linear constraints at most are required per reach. Constraint elimination techniques are developed that can further reduce the number of constraints necessary. As a means of highlighting the potential power of these techniques to large‐scale models they are applied to two well‐known examples from the literature.
Properties of the three‐parameter log normal probability distribution
Authors: Burges Stephen J. , Lettenmaier Dennis P. , Bates Courtney L.
Published: February 2008

Mathematical properties of the three‐parameter log normal probability distribution are detailed. Two methods for estimation of the third parameter a are compared. The estimator of a using sample mean, median, and standard deviation is found to be more variable and have larger bias for distributions of interest in operational hydrology than the estimator using sample mean, standard deviation, and skew. Graphical solutions for the third parameter a are presented; a single feasible value of a is shown to result when the skew estimator is used; two feasible solutions result when the median estimator is used. The smaller of the two solutions is shown to correspond to skews of less than 5.87 and hence is the desired solution in most hydrologic applications.
Persistence of selected antitranspirants
Authors: Kreith Frank , Taori Ashok , Anderson Jay E.
Published: February 2008

The short‐ and long‐term effectiveness of two film‐forming and two physiologically active antitranspirants was evaluated on tobacco leaves under controlled experimental conditions. The physiologically active antitranspirants (phenylmercuric acetate and monoglycerol ester of n‐decenyl succinic acid) initially reduced water loss to less than 40% of controls, but their effectiveness diminished sharply within 2–3 days. Treatment with the film‐forming antitranspirants (Wilt Pruf and Mobileaf) resulted in initial transpiration reductions to 50–65% of controls, but the duration of effectiveness was longer with these than with the metabolic agents. The results are compared with those of previous studies, and implications for large‐scale antitranspirant applications are discussed.
Carbon 14 dating of groundwater from closed and open systems
Authors: Wigley T. M. L.
Published: February 2008

Groundwaters may be dated by using carbon 14, provided that the raw data are properly adjusted. However, adjustment factors determined from geochemical or isotopic measurements and based on simple models of carbonate dissolution do not always agree with adjustment factors obtained by independent means. In this paper, established adjustment methods are reinterpreted in terms of closed and open system models of carbonate dissolution, and it is suggested that these models provide a sounder framework for determining adjustment factors. Hypothetical and real examples are considered, and it is shown that some otherwise anomalous results may be explained in terms of the closed and open system models.
Subsurface flow from snowmelt traced by tritium
Authors: Martinec J.
Published: February 2008

An explanation is offered of the apparent discrepancy between the small velocities of subsurface flow and the watershed response. Environmental tritium in the hydrological cycle provided evidence for a new insight into the runoff mechanism. By this concept the quick reaction of outflow to a massive groundwater recharge is brought to agreement with the long residence time of the infiltrated water.
Computer simulation of the snowmelt and soil thermal regime at Barrow, Alaska
Authors: Outcalt S. I. , Goodwin C. , Weller G. , Brown J.
Published: February 2008

An annual snow‐soil simulator for arctic tundra was developed by using coupled models of surface equilibrium temperature and substrate thermal diffusion. Snow ripening, melt, and accumulation are modeled in the simulator which is forced with daily weather data. The simulator predicts that a snow fence array capable of producing drift deeper than 4.2 m will initiate permanent snowfield at Barrow, Alaska. Such a man‐induced snowfield could serve as a reliable source of freshwater for Barrow and similar villages in the north slope region of Alaska. Further analysis indicated that albedo reduction due to dust fall, snow removal, etc., is dominant over aerodynamic effects in producing the early spring meltout observed at Barrow Village.
On a derivable formula for long‐wave radiation from clear skies
Authors: Brutsaert Wilfried
Published: February 2008

A derivation is presented for the effective atmospheric emissivity to predict downcoming long‐wave radiation at ground level under a clear sky and for a nearly standard atmosphere. The results are in good agreement with those obtainable with empirical formulae based on water vapor pressure and temperature. However, the proposed formulation has the advantage that its simple functional form is based on physical grounds without the need for empirical parameters from radiation measurements. Also, in contrast to the empirical equations, it may be adjusted in a simple way to reflect changes in climatic and atmospheric conditions.
Models of land and water allocation to improve environment and water quality through soil loss controls
Authors: Heady Earl O. , Nicol Kenneth J.
Published: February 2008

A model is developed that is applicable to all agricultural land in the United States. The model includes 223 producing areas, 1891 land resource areas, and 51 water supply regions. Different cropping systems and technologies are defined for each crop and livestock system in each of 1891 land resource regions. Hence the programing model is of very large scale, since it also includes a transportation submodel and market regions. As a means of water quality improvement, limits are placed on the per acre per year soil loss as a means of reducing sedimentation and the transport of nitrogen and phosphates into streams. A nitrogen balance equation limits fertilizer purchases and forces utilization of livestock wastes in the region. The model forces a land use system and set of technologies over the country and interregionally that has soil loss unrestricted, at 10 tons per acre, at 5 tons per acre, and at 3 tons per acre. The unrestricted and 5‐ton limits are reviewed in this paper in relation to impacts on soil loss (reduced about 25%), crop distribution, technology, water use, and farm prices.
Nucleation characteristics of stream water and frazil ice nucleation
Authors: Osterkamp T. E. , Gilfilian R. E.
Published: February 2008

A drop‐freezing experiment was used to study the nucleation characteristics of some natural water samples taken from a supercooled stream in interior Alaska. A histogram of drop‐freezing events, the differential nucleus spectrum, and the cumulative nucleus spectrum describe the experimental results. The drops froze over a temperature range from −4.3°C to −13.9°C with an average nucleation temperature of −8.2°C ±1.5°C. The results of these experiments are compared to observations made during periods of frazil ice production in the stream. It is concluded that the supercooling necessary for spontaneous heterogeneous nucleation of ice in a thin surface layer of stream water would be ∼ −4°C. Since the surface temperature of the supercooled stream was found to be 0°C ± 0.5°C, frazil ice crystals cannot be nucleated spontaneously in the surface layer of water.
Identifying the parameters of an aquifer cell model
Authors: Hefez E. , Shamir U. , Bear J.
Published: February 2008

Cell models are commonly used for forecasting water levels in aquifers. Calibration of such models is achieved through identification of their parameter values, the transmissivities and storativities of all cells, using historical data. Several methods of formulating the identification as a linear or quadratic programing problem are presented. Examples are given, results of the various methods compared, and the sensitivity of these results to errors in the data is discussed. Inflows or outflows during historical periods may also be determined by the same methods; an example for a real aquifer is presented.
Minimizing the operating and capital costs of water supply projects
Authors: Lucke James B.
Published: February 2008

Sequencing the expansion of water supply projects to minimize discounted operating and capital costs can be formulated graphically as finding a least cost path from the present to the fully expanded future. In light of this model a simple dynamic programing algorithm or minimal cost network algorithm can be readily used in conjunction with a computer to solve the problem.
Onset of thermohaline convection in a cavernous aquifer
Authors: Rubin Hillel
Published: February 2008

In some groundwater aquifers, geothermal activity may lead to thermal convection. In such cases, very often saline hot water is transferred from the deep layers of the aquifer into the upper layers. There is an hypothesis that such a mechanism does exist in the deep regions of the Floridan aquifer. However, the deep zone of the Floridan aquifer is extremely cavernous. Therefore even very slow motions may lead to an intensive dispersion of soluted materials and heat as well as to turbulent effects demonstrated by the invalidity of the laminar Darcy law. In this study all these effects and their connection with the onset of thermohaline convection were investigated. It was found possible to define in the field a plane where applied perturbations are the most disturbing to the flow field. In this plane, convection motions initiate. This plane forms an angle θc with the unperturbed velocity vector. Angle θc varies according to flow conditions between 0° and 90°. Approaches were developed for the determination of instability criteria for different regions of the Reynolds number.
Investment sequencing, allocation, and learning in the design of water resources systems: An empirical application
Authors: Rausser Gordon C. , Willis Cleve E.
Published: February 2008

Four of the more important unresolved problems in the design of water resources systems involve a determination of methods to deal with technological progress (e.g., new desalting processes), availability of water from more than a single supply source, the rate of investment in the capital complex employed to exploit the resource along with the allocation of water once the capital complex is in place, and price sensitive demands for water. The importance of these issues is demonstrated, and a decision framework is advanced which formally incorporates each along with a new technique for solving large‐scale investment‐sequencing and water allocation problems. The robustness and convergence properties are formally demonstrated. Finally, the framework is applied to an empirical situation in California with rather encouraging results.
The age of groundwater in the chalk of the London Basin
Authors: Smith D. B. , Downing R. A. , Monkhouse R. A. , Otlet R. L. , Pearson F. J.
Published: February 2008

Isotope techniques have been applied to a study of groundwater movement in the Chalk of the London Basin. The ‘age’ of the water as determined by 14C measurements increases toward the central confined part of the basin where it exceeds 25,000 years and therefore originated during the Pleistocene. The age distribution supports previous interpretations of the permeability pattern, partly based on hydro‐chemistry. Measurements of tritium and the stable isotope ratios of carbon, oxygen, and deuterium were also made. The 13C/12C ratio varied from −13‰ at outcrop to values less negative than −1‰ in the central part of the basin, which is approaching the value of +2.35‰ for the aquifer matrix. The 18O and deuterium ratios indicate that the Pleistocene waters were recharged at a mean air temperature less than 1°C cooler than that of present day recharge, probably because recharge in the Pleistocene was limited to summer periods because of frozen ground in the winter.
A Markov Chain Model of daily rainfall
Authors: Haan C. T. , Allen D. M. , Street J. O.
Published: February 2008

The design of many water resources projects requires knowledge of possible long‐term rainfall patterns. A stochastic model based on a first‐order Markov chain was developed to simulate daily rainfall at a point. The model uses historical rainfall data to estimate the Markov transitional probabilities. A separate matrix is estimated for each month of the year. In this research, 7 × 7 transitional probability matrices were used. The model is capable of simulating a daily rainfall record of any length, based on the estimated transitional probabilities and frequency distributions of rainfall amounts. The simulated data have statistical properties similar to those of historical data.
An analysis of water flow in dry snow
Authors: Colbeck S. C.
Published: February 2008

The equations describing water movement in a dry snow cover are derived, and examples of flow through ripe, refrozen, and fresh snows are given. The grain size of snow has a large effect on the timing of water discharge. Water is retained by dry snow to raise its temperature and satisfy the irreducible water saturation. These requirements delay and reduce runoff following rain on dry snow.
Optimal design of single reservoir system using δ Release Policy
Authors: Luthra Sham S. , Arora Sant R.
Published: February 2008

Reservoirs provide storage capacity which serves to match more ideally the demands and supplies of water. The amount of storage required very critically depends upon the constraints on freeboard, minimum pool level, and upon the permissible limits on releases. Release policy also plays a very critical role. During the recent years, one of the policies which has attracted a great deal of attention is what has come to be known as the linear decision rule policy. This policy passes on the variability of a particular period's inflow to the next period's release. This paper offers another release policy, which is called the δ release policy, where δ is a parameter whose value distributes the effects of inflow variability between the releases and the pool level. This paper shows that δ release policy requires smaller reservoir capacity than that obtained by the linear decision rule policy.
A stable estimator for linear models: 2. Real world hydrologic applications
Authors: Natale L. , Todini E.
Published: February 2008

Different types of estimators are used to evaluate the parameters of the linear models of two hydrologic systems. The first system is relevant to the junctions of the Arno River and the Chiana River in Italy. The second system is relevant to the hydrologic basin of the Sieve River, a tributary of the Arno. In all the cases examined, which are well represented by linear models, the constrained estimator shows its higher level of efficiency.
A northern snowmelt‐flood frequency model
Authors: Carlson Robert F. , Fox Patricia
Published: February 2008

A rainfall‐flood frequency model is examined and converted to a snowmelt‐flood frequency model for use in northern subarctic regions. The model is applied to the Chena River at Fairbanks, an interior Alaskan basin, with emphasis on evaluation of the model for use on watersheds with few or no previous discharge records. The evaluation includes examination of the theoretical development and assumptions of the original model, adaptation of the original model to a snowmelt‐flood frequency model, sensitivity analysis, and comparison with results from other techniques and the observed frequency series. While the model suffers from certain inconsistencies, it does seem to be a useful tool for flood frequency design for subarctic watersheds with sparse data records.
Modeling monthly hydrologic persistence
Authors: Young G. K. , Jettmar R. U.
Published: February 2008

This paper empirically studies the autocorrelations and Hurst parameter properties for monthly streamflow for a set of U.S. Geological Survey gaging stations in the eastern United States. The analysis is motivated by a desire to develop operational criteria to select persistence measures and generating models. The work is part of a larger effort to evaluate the trade‐offs between complex and simple data generators. Markov generators are simple in comparison to the more complex self‐similar methods. Other papers in this effort are those by Chi et al. (1973) and Jettmar and Young (1975). Monthly streamflow data are found to have Hurst statistics similar to annual data. Least squares is presented as a possible method to estimate persistence parameters and select generating models. Empiric autocorrelations are treated as data in a fit of theoretic covariance functions by minimum squared error. The Hurst and least squares estimators are nearly the same. The lag 1 correlation is much smaller than least squares Markov estimators. A step‐by‐step procedure is suggested for implementation of least squares persistence analysis.
The application of the overburden potential theory to swelling soils
Authors: Towner G. D.
Published: February 2008

From a consideration of alternative loading paths in the shrinkage diagram of swelling soils it is shown that hysteresis in the relationship between the voids ratio and the moisture ratio may occur even though no actual reversals of loading have been allowed nor any irreversible structural changes have taken place. It is therefore argued that the application of the overburden potential theory to the analysis of situations such as water profiles above water tables in vertical soil columns is questionable. The need for experimental studies is stressed.
Influence of matrix conduction upon hydrogeophysical relationships in arenaceous aquifers
Authors: Worthington Pauf F.
Published: February 2008

The relationship of formation resistivity factor to effective porosity or intergranular permeability in water‐saturated sands is shown to be best defined where the solid constituents do not contribute significantly to the conduction of applied current or where corrections for this contribution have been applied to the measured formation resistivities. It is demonstrated that, in the particular case of an argillaceous sand sorted according to its matrix conduction properties, useful relationships between formation resistivity factor and intergranular permeability can be established without any process of correction, provided that porosity and electrolyte salinity do not vary markedly within the formation. This finding is used to resolve the paradox that formation resistivity factor has been reported to increase with intergranular permeability in certain sands and to decrease with increasing values of this same hydrological parameter in others.