Applicability of Effective Parameters for Unsteady Flow in Nonuniform Aquifers

As a rule, a groundwater aquifer consists of materials whose characteristics vary in space. On account of the uncertainty in determining these characteristics and their variation in the field and also for the sake of parsimony, it is often desirable to assume that the aquifer may be considered homogeneous and uniform; in other words, the prototype is modeled by an equivalent homogeneous and uniform aquifer with a set of effective parameters, which displays the same flow characteristics. To study the applicability of this concept, a Monte Carlo technique was used in the simulation of unsteady gravity drainage from a large unconfined aquifer. For given criteria of hydraulic equivalence applied to the outflow rate, effective parameters (hydraulic conductivity and drainable porosity) were obtained, hose variation was studied. It was found that only under certain conditions is it possible to define a single set of effective parameters to reproduce the median outflow hydrograph. The effective parameters were found to depend on both the distribution of the hydraulic conductivity and its spatial correlation.

[1]  W. Brutsaert,et al.  The Relative Importance of Compressibility and Partial Saturation in Unconfined Groundwater Flow , 1984 .

[2]  Gedeon Dagan,et al.  Analysis of flow through heterogeneous random aquifers: 2. Unsteady flow in confined formations , 1982 .

[3]  A. Mantoglou,et al.  The Turning Bands Method for simulation of random fields using line generation by a spectral method , 1982 .

[4]  G. Dagan.  Stochastic modeling of groundwater flow by unconditional and conditional probabilities: 1. Conditional simulation and the direct problem , 1982 .

[5]  Keith Beven,et al.  Comments on ‘A stochastic‐conceptual analysis of rainfall‐runoff processes on a hillslope’ by R. Allan Freeze , 1981 .

[6]  Allan L. Gutjahr,et al.  Stochastic models of subsurface flow: infinite versus finite domains and stationarity , 1981 .

[7]  Michael D. Dettinger,et al.  First order analysis of uncertainty in numerical models of groundwater flow part: 1. Mathematical development , 1981 .

[8]  R. Allan Freeze,et al.  A stochastic‐conceptual analysis of rainfall‐runoff processes on a hillslope , 1980 .

[9]  R. Allan Freeze,et al.  Stochastic analysis of steady state groundwater flow in a bounded domain: 2. Two‐dimensional simulations , 1979 .

[10]  J. P. Delhomme,et al.  Spatial variability and uncertainty in groundwater flow parameters: A geostatistical approach , 1979 .

[11]  Gedeon Dagan,et al.  Models of groundwater flow in statistically homogeneous porous formations , 1979 .

[12]  B. Sagar,et al.  Galerkin Finite Element Procedure for analyzing flow through random media , 1978 .

[13]  J. R. Macmillan,et al.  Stochastic analysis of spatial variability in subsurface flows: 2. Evaluation and application , 1978 .

[14]  Allan L. Gutjahr,et al.  Stochastic analysis of spatial variability in subsurface flows: 1. Comparison of one‐ and three‐dimensional flows , 1978 .

[15]  George F. Pinder,et al.  Simulation of groundwater flow and mass transport under uncertainty , 1977 .

[16]  Ignacio Rodriguez-Iturbe,et al.  Rainfall generation: A nonstationary time‐varying multidimensional model , 1976 .

[17]  R. Freeze.  A stochastic‐conceptual analysis of one‐dimensional groundwater flow in nonuniform homogeneous media , 1975 .

[18]  I. Rodríguez‐Iturbe,et al.  On the synthesis of random field sampling from the spectrum: An application to the generation of hydrologic spatial processes , 1974 .

[19]  Lyman S. Willardson,et al.  Sample Size Estimates in Permeability Studies , 1965 .

[20]  T. Talsma,et al.  Investigation of water‐table response to tile drains in comparison with theory , 1959 .

[21]  W. Brutsaert,et al.  Research Note On the first and second linearization of the Boussinesq equation , 1966 .

[22]  M. Boussinesq.  Essai sur la théorie des eaux courantes , 1873 .