Groundwater parameter estimation by optimization and dual reciprocity finite differences method

Abstract

A new solution method called the dual reciprocity finite differences method (DRFDM) is proposed. The method combines the finite differences method and optimization technique, and can be implemented in a spreadsheet to solve groundwater parameter estimation problems. In the DRFDM model, the hydraulic heads and transmissivities in the solution domain are obtained using limited hydraulic heads and/or transmissivities. The method is implemented as an objective function. Three different scenarios are examined. A set of transmissivities are used in the first scenario. In the second scenario, only hydraulic heads are used. In the third scenario, both transmissivities and hydraulic heads are used in an objective function. A spreadsheet solver is used as an optimization tool. Two examples taken from literature are used to verify the method; one of which has an analytical solution, and the other has not. Good agreement between the DRFDM model output and both analytical and observed values is obtained only when limited transmissivity values or both hydraulic heads and transmissivity values are known. The presented method was not effective in the studied cases in which only hydraulic heads were known. Copyright © 2005 Begell House, Inc.