HR: 1340h
AN: H13A-1329    [Abstracts]
TI: Numerical Volumetric Analysis of Spatially Dependent Transmissivity and Storativity in Heterogeneous Aquifers
AU: * Rhode, K
EM: rhod3892@uidaho.edu
AF: Hydrology Program, Dept. of Geological Sciences, University of Idaho, PO Box 443062, Moscow, ID 83843 United States
AU: Osiensky, J
EM: osiensky@uidaho.edu
AF: Hydrology Program, Dept. of Geological Sciences, University of Idaho, PO Box 443062, Moscow, ID 83843 United States
AB: Aquifer transmissivity (T) and storativity (S) values control the rate and areal extent of propagation of the cone of depression from a pumped well. It has been documented recently that transmissivity and storativity, reflect the geometric and arithmetic means, respectively, of the area contacted by the cone of depression. However, these findings do not reflect a volumetric evaluation of the cone of depression within the heterogenities. Analysis of spatial, volumetric variations within the cone of depression expressed at the potentiometric surface, offers a more general solution to evaluate the meaning of T and S values. Log-normal and normal distributions of hydraulic conductivity as block heterogeneities were established within model domains for simulated aquifer tests. By analyzing the volumetric evolution of the cone of depression observed in the potentiometric surface, we are able to illustrate the averaging of transmissivity as a function of time, and distance from the pumping well for the entire affected aquifer. Volumetric analysis of simulated aquifer tests show an exponential decrease in the arithmetic, harmonic, and geometric weighted mean transmissivity within the evolving cone of depression through time, approaching steady, basin-wide averages. Transmissivity estimates derived for single observation wells by conventional testing methods (i.e., Theis, 1935; Cooper and Jacob, 1946) are found to increase with increasing radial distance from the pumping well. However, when the same observation well drawdown data are plotted together with, and constrained by, the drawdown curve for the pumping well, a family of drawdown curves is derived that yields transmissivity values that are consistent with the volumetric, weighted, mean transmissivity values calculated for the entire cone of depression for specific periods of time (i.e., areal extent).
DE: 1829 Groundwater hydrology
DE: 1869 Stochastic hydrology
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005