摘要:

A generalized Darcy's law for nonuniform flows in which the pressure gradient depends on the velocity and its derivatives is adopted. The permeability coefficient, as well as a new coefficient, is investigated with the aid of the averaged dissipation equation. The additional coefficient appearing in the generalized law is estimated with the aid of a cell model, and the generalized law is employed in order to solve a few problems (Couette flow past a porous boundary, refraction at the boundary between two porous samples, and flow around a thin partition). Deviations from Darcy's law are found to be confined to thin layers near the medium boundaries.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00001

年代:1979

数据来源: WILEY

摘要:

Interest has increased recently in water recycling and reuse. The possible economic feasibility of reuse and recycling dramatically increases the complexity of designing an optimal water delivery system. In this paper we present a nonlinear model which takes into account both flow requirements and water quality. Because of the model's transshipment formulation the solution technique seems to be effective in aiding the design decisions.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00008

年代:1979

数据来源: WILEY

摘要:

The flow and dissolved iron content of two small streams draining a woodland basin and a recently deforested basin on a granite pluton in Kershaw County, South Carolina, were measured biweekly from September 1974 through August 1975. During spring and summer the flow of the stream draining the deforested basin was reduced relative to that of the woodland basin because of the higher transpiration associated with rapid biomass accumulation by the newly established vegetation in the deforested basin. The observed relative reduction in flow was accompanied by a relative increase in iron concentration in the flow from the deforested basin. Analysis of the data also indicates that the rate of export of dissolved iron from both basins is independent of stream discharge. These observations suggest that the dissolved iron content of these streams is controlled by the dilution of iron‐rich groundwater by essentially iron‐free surface runoff and shallow interflow. A simple mixing model based on this hypothesis has been developed and found to fit the d

ISSN:0043-1397    

DOI:10.1029/WR015i001p00015

年代:1979

数据来源: WILEY

摘要:

Several commonly used procedures for sampling coarse riverbed material result in samples that are biased toward the larger particles. Kellerhals and Bray (1971) recommend correcting the bias by scaling the sample frequency of each frequency interval by the inverse of the appropriate power of the mean grain size of the interval. If, however, grain size is assumed to be log normally distributed, it is possible to determine the distribution of the biased sample. This provides explicit bias factors for the sample moments.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00021

年代:1979

数据来源: WILEY

摘要:

Two alternative mathematical models are presented that are suitable for numerical simulation of geothermal reservoirs. The general mathematical model describes the three‐dimensional flow of single‐component water (both one and two phase) and the transport of heat in porous media. It is composed of two nonlinear partial differential equations, posed in terms of fluid pressure and enthalpy, and appropriate boundary conditions. An alternative quasi‐three‐dimensional model is derived by partial integration (in the vertical dimension) of the three‐dimensional equations. The reservoir is assumed to have good vertical communication so that vertical equilibrium (gravity segregation) between steam and water is achieved. The resulting equations, posed in terms of vertically averaged pressure and enthalpy, include effects of an inclined, variable‐thickness reservoir and mass and energy leakage to con

ISSN:0043-1397    

DOI:10.1029/WR015i001p00023

年代:1979

数据来源: WILEY

摘要:

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

ISSN:0043-1397    

DOI:10.1029/WR015i001p00031

年代:1979

数据来源: WILEY

摘要:

Most natural porous formations display significant variations in space of permeabilityKand storativityS. Such formations are regarded as random structures characterized by the permeability frequency distribution and its autocorrelation. With the aid of three basic length scales (l, microscale; £, integral scale ofKautocorrelation; andL, length scale of space change of averageK) a classification of aquifers is suggested. A similar classification is proposed for the flow regimes. The study is limited to statistically homogeneous or slowly varying formations (£ ≪L) and to uniform or slowly varying (in space and time) flows. In the section dealing with steady flows, effective permeability, as well as variances of head gradient, specific discharge, and head, is computed for one‐, two‐, and three‐dimensional flows. Bounds and an estimate of the effective permeability in terms of a log normal permeability distribution are given. The computations are based on physical, simplified models of formation structure. It is shown that the head variance is grossly overestimated for one‐dimensional flow through blocks ‘in series,’ and the same is true for specific discharge for layers ‘in parallel.’ The two‐ and three‐dimensional variances are much lower and are close to each other. The unsteady flow is analyzed with the aid of the relaxation time needed for blocks of differentK, Sto adapt to the environment. For flows which change slowly and uniformly the effective permeability is that derived for steady uniform flows, and the effective storativity is equal to theSarithmetic mean. The head gradient variance computed with the aid of some physical models is compared with that of steady uniform flow, and it is shown that for sufficiently slow time changes the flow field can be considered momentarily uniform. The various results are employed to estimate effective properties, as well as fluctuations of the head and specific discharge, in aquifers, with possible applications to prediction, the inverse problem, and

ISSN:0043-1397    

DOI:10.1029/WR015i001p00047

年代:1979

数据来源: WILEY

摘要:

A model for estimating areal evaporation and transpiration is modified slightly to provide estimates of annual lake evaporation from monthly observations of temperature, humidity, and sunshine duration (or radiation) in the land environment. The model estimates tend to be higher than the more conventional estimates in humid areas and lower in arid areas, with the latter tendency particularly noticeable in the case of Lake Nasser on the Nile River. However, the results agree very well with comparable water budget estimates for Lake Hefner in Oklahoma, the Salton Sea and Silver Lake in California, Pyramid and Winnemucca lakes in Nevada, Lake Ontario on the border between New York and Ontario, and Dauphin Lake in Manitoba. They also compare reasonably well with energy budget estimates of the evaporation from Lake Mead on the border between Arizona and Nevada when the net inflow of heat is taken into account. A technique that provides such realistic results over a wide range of depths and environments with readily available data should prove very useful in water resource or environmental impact studies. Examples of such uses are provided by maps of Canada and the southeastern United States that show average annual values of the lake evaporation, and average annual values of the difference between the evaporation from a projected reservoir, and the combined evaporation and transpiration from the area before flooding.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00064

年代:1979

数据来源: WILEY

摘要:

Current meter observations and hydrological and meteorological data collected primarily during 1974 formed the basis upon which the monthly water balance of Georgian Bay could be estimated. The data were used to derive a first approximation of the exchange of water between Georgian Bay and main Lake Huron. The net exchange across Main Channel at depths greater than 5 m was determined from extensive current meter observations while the exchange in the upper 5 m was the residual necessary to achieve a balanced water budget. The results illustrate that during the stratified season (May through November) the transport of water through Main Channel is also stratified with surface water moving into Georgian Bay from main Lake Huron while continuity is maintained by net outflow at depths greater than 5 m. Total annual supply from runoff and direct precipitation is nearly twice as large as combined losses from evaporation and flow to North Channel. Residence and flushing times for water in the bay are estimated at 5.1 and 5.7 years, respectively.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00077

年代:1979

数据来源: WILEY

摘要:

Although transport of the visible component of solar radiation in a water body strongly influences thermal structure and the growth of photosynthetic organisms, little is known about the inherent radiative properties which govern this transport. These properties include the extinction, scattering, and absorption cross sections, as well as the scattering phase function. In this study, systematic property measurements have been made for two special cases: the wastewater suspension and the symbiotic algal culture. In both cases, extinction is dominated by scattering processes (rather than by absorption), but cross sections associated with the symbiotic cultures are typically a factor of 6 larger than those associated with the wastewater. In both cases the scattering phase function is strongly peaked in the forward direction.

ISSN:0043-1397    

DOI:10.1029/WR015i001p00085

年代:1979

数据来源: WILEY