摘要:

Transfers of water from irrigation to municipal and industrial uses are seen as a low‐cost approach to the water supply problems of western cities. Rural areas of origin protest that market transfers ignore indirect economic, political, social, fiscal, and environmental effects of changes in water use. The capacity of five different water transfer institutions: the market, courts, legislature, special purpose districts, and administrative agencies, to develop and weigh information about indirect and nonuser impacts is analyzed and compared. All five forums are found to have biases regarding the type of information used. Markets process information on direct economic costs and benefits well but ignore third‐party costs; legislative bodies are sensitive to information about indirect and nonuser impacts but distort information on direct benefits and costs; neither the judiciary nor the water agency is likely to consider community and social impacts of water transfers. Special districts could consider both direct and indirect values but are often controlled by a leadership elite, pursuing narrow goals with minimum membership participation. The appropriate forum for decision making depends upon our priorities among values and on the values that are at stake in particular iss

ISSN:0043-1397    

DOI:10.1029/WR024i004p00473

年代:1988

数据来源: WILEY

摘要:

A model was developed to group precipitation samples from any location into four strata that represent collections of similar chemistry. Logic and cation frequency were used to first define low‐ and high‐salt samples, and then regression analysis was used to define low‐ and high‐H samples. Low‐H concentrations ranged between 0 and 13 μeq/L. Hydrogen regressed on the sum of NO3+ SO4showed two consistent equations: one for normal H concentrations and one for emission‐related, high‐H concentrations. Delta analysis (the change in concentration between group means) and analysis of regression residuals between ion pairs and a third common ion revealed strong correlations for H: NO3, H: SO3, NH4:SO4, and Na: Cl in low‐salt, highly acid precipitation samples. Hydrogen, SO4, NO3, and NH4compose 95% of acid precipitation chemistry in the United States. Significant correlations for NH4: NO3and all other ion pairs did not exist in samples from highly acid, low‐salt collections. Nitrate and SO4carried H at average portions of 36 and 64%, respectively, regardless of H concentration. Variation in these portions of ±15% was site specific and not a function

ISSN:0043-1397    

DOI:10.1029/WR024i004p00481

年代:1988

数据来源: WILEY

摘要:

Analytical solutions for the pressure distribution and the flow field are derived for several idealized situations involving an injection well and a vertical plane or cylindrical interface between two fluids of different density and viscosity in an infinite anisotropic aquifer bounded by two horizontal planes. The interface, or transition zone, between the two fluids may be either sharp or of finite width. The buoyancy flow induced by the density difference will cause the two‐fluid interface to tilt. A characteristic time scale for the buoyancy tilting rate is deduced. The conditions at the well are found to have only a small influence on the buoyancy flow except very close to the well. The buoyancy flow decreases with increasing width of the transition zon

ISSN:0043-1397    

DOI:10.1029/WR024i004p00493

年代:1988

数据来源: WILEY

摘要:

The motion of a two‐fluid interface in an aquifer is a combination of buoyancy flow and forced convection. The buoyancy flow, which is due to density variations of the fluid, and the forced convection, which acts on the viscosity variations, will cause the two‐fluid interface to tilt. The basic case of a plane interface between two immiscible fluids of different density and viscosity in an infinite anisotropic aquifer bounded by two horizontal planes is analyzed in detail. The groundwater flow in the aquifer is treated as a superposition of buoyancy flow and forced convection. The buoyancy flow and the forced‐convection components are shown by analytical methods to be related to each other. The tilting angle of the two‐fluid interface is given by a simple formula containing only two parameters. There exists a certain stationary tilting angle, the stability of which depends on the two visc

ISSN:0043-1397    

DOI:10.1029/WR024i004p00507

年代:1988

数据来源: WILEY

摘要:

A study was undertaken to evaluate the processes affecting the chemistry of shallow groundwater associated with agricultural drainage systems in the western San Joaquin Valley, California. The study was prompted by a need for an understanding of selenium mobility in areas having high selenium concentrations in shallow groundwater. Groundwater samples were collected along transects in three artificially drained fields where the age of the drainage system varied (15, 6, and 1.5 years). Selenium concentrations in the drain water also varied (430, 58, and 3700 μg/L, respectively). Isotopic enrichment and chemical composition of the groundwater samples indicate that saline‐ and selenium‐enriched water has evolved as a result of evaporation or transpiration of groundwater. This evaporated, isotopically enriched water is being displaced by more recent, less saline irrigation water percolating through the root zone. This displacement seems to be a process whereby sodium chloride and sodium sulfate water is being replaced by more dilute calcium sulfate and calcium bicarbonate w

ISSN:0043-1397    

DOI:10.1029/WR024i004p00516

年代:1988

数据来源: WILEY

摘要:

The Integrated Lake Watershed Acidification Study model was modified to accept pulse inputs of calcium carbonate dry deposition on user‐specified dates and over selective areas of the Woods Lake watershed. Responses at the lake outlet and in several soil horizons in the catchment were simulated for various liming scenarios comparing separate applications to both lake and land surfaces, during both spring and winter seasons, and at two different dose levels over the land area. The direct lake application was characterized by large, immediate, short‐duration increases in lake outletpH and alkalinity, attributable to a sudden influx of alkaline material that quickly flushed through the aquatic system. The terrestrial application was characterized by lower magnitude, more gradual and longer duration increases in both lake outlet, and soilpH and alkalinity, attributable to enhancement of the base saturation at soil cation exchange sites. Inorganic aluminum concentrations, a concern with respect to fishery health, were only temporarily reduced following the lake application, while dramatic reductions were sustained for several decades following the terrestrial application; this suggests terrestrial liming slows the rate of chemical weathering and leaching of aluminum. The seasonal timing of the lime application significantly affected the magnitude and duration of the response in the lake application, but not in the land treatment, suggesting that the effectiveness of land treatment may not depend on seasonal flow dynamics. In addition, this indicates that mean hydraulic residence time may have certain limitations as an indicator of the retention time of chemical species introduced to an entire watershed, depending on the extent to which the land catchment influences adjacent water chemistry. These results suggest that for lakes and streams having short retention times, liming part or all of the land catchment might be advantageous to liming only the lake as a means of mitigating lake acidity. This conclusion and the potential for concurrent mitigation of terrestrial effects employing land catchment liming requires further experimental st

ISSN:0043-1397    

DOI:10.1029/WR024i004p00525

年代:1988

数据来源: WILEY

摘要:

There is much concern over the effects of acidic deposition on soils and drainage waters. To better understand the processes regulating the acidification of surface waters, computer models have been developed which utilize equilibrium calculations to predict the concentration of chemical parameters such aspH, acid neutralizing capacity, dissolved inorganic carbon, Al and SO42−. A simple chemical equilibrium model (ALCHEMI) was used to evaluate the effect of uncertainty in the measurement of chemical constituents on thermodynamic calculations. For calculations wherepH was not allowed to vary (fixedpH calculations), uncertainty in Al speciation was small (maximum of 7%) and largely due to imprecision in the measurement of total F andpH. When calculations were made from electroneutrality based on measured constituents (variablepH calculations), most of the uncertainty associated with the values of output parameters was due to imprecision in the determination of SO42

ISSN:0043-1397    

DOI:10.1029/WR024i004p00533

年代:1988

数据来源: WILEY

摘要:

A three‐dimensional finite element model combined with an optimization approach based on linear mixed integer programming is developed and applied to assist in the design of the dewatering system for the electronuclear plant to be built by the Italian Electric Agency (ENEL) in Trino Vercellese, northwestern Italy. The foundations site is encompassed by a 25‐ to 35‐m deep plastic wall with the purpose of protecting the unconfined aquifer from the significant water table lowering required by the construction project. To reduce further the propagation of the depression cone a large amount of the water pumped out is reinjected through “ad hoc” recharge ditches. The finite element optimization model includes both the natural and the artificial constraints and provides several optimal withdrawal strategies for the dewatering system design concerning the distribution of the abstraction wells and the corresponding pumping rates. Physical and economical objective functions are explored and the related solutions are

ISSN:0043-1397    

DOI:10.1029/WR024i004p00541

年代:1988

数据来源: WILEY

摘要:

Construction of flow nets in most hydrogeologic field problems is complicated by nonexistence of orthogonality between streamlines and hydraulic head lines in anisotropic porous media. The nonexistence of orthogonality can be circumvented by transformation of the anisotropic porous medium into an isotropic one. Flow nets are valuable in generation of a numerical solution grid for a contaminant transport equation formulated along the direction of flow and the direction orthogonal to flow. Effect of flow domain transformation on contaminant transport simulation is not known. The flow domain transformation can be avoided by constructing flow nets with streamlines and pseudopotential lines. The pseudopotential lines are based on the theory of pseudopotential function. A discussion of the theory in isotropic porous media exists in literature. To my knowledge, this is the first time that the theory is being extended to anisotropic porous media. An integration procedure is used to evaluate values of pseudopotential function and hydraulic head along a streamline. A comparison of flow nets based on pseudopotential lines and hydraulic head lines indicates that pseudopotential lines are more useful than hydraulic head lines in simulation of contaminant transport in saturated groundwater flow systems.

ISSN:0043-1397    

DOI:10.1029/WR024i004p00553

年代:1988

数据来源: WILEY

摘要:

The optical characteristics of sediment suspensions in the glacierfed lake Veitastrondsvatn are examined to explain observed color variations. The color depends on the wavelength where the ratio between the backward scattering coefficient and the absorption coefficient of the suspension has its maximum, and this usually coincides with the wavelength where the absorption has its minimum. It is found that the absorption coefficient of the small particles of clay and silt size decreases with increasing wavelength, but that the absorption coefficient of the suspension obtains a minimum in the green part of the spectrum, due to the strong absorption of red light by water. The suspension of such particles in the surface layer of the lake will then appear green. The coefficients of larger particles of sand size are almost independent of wavelength, with no significant maximum or minimum, and river waters close to the glacier fronts, which are dominated by these particles, will appear milky.

ISSN:0043-1397    

DOI:10.1029/WR024i004p00561

年代:1988

数据来源: WILEY