Estimation of Hydraulic Diffusivity in Stream-Aquifer System

Abstract

The Laplace transform of convolution equation, which relates aquifer response to boundary per- turbation, expresses explicitly the hydraulic diffusivity in terms of the Laplace transform parameter, changes in stream stage, and fluctuations of piezometric level at a point near the stream. Hydraulic diffusivity has been estimated using the Laplace transform approach. The diffusivity has also been determined from observed re- sponse of an aquifer and the boundary perturbation using the Marquardt method, a least-squares optimization technique. If the observed data are free from random error, the diffusivity can be estimated accurately using the Laplace transform approach. Unlike the least-squares optimization method, the Laplace transform technique automatically gives less weight to the latter part of the aquifer response and thereby to the random error contained in it. Discrete kernel coefficients have been derived, using which the water level rise in an aquifer that can be predicted for any variation in stream stage.