Identifying Impervious Boundary and Aquifer Parameters from Pump-Test Data

Abstract

The common field problem of identifying and locating impervious aquifer boundaries is generally solved by analyzing the pump-test data. The estimate of the distance between the image well and the observation well (r′) is required for locating the boundary. Popular methods of estimating r′ either use the concept of fully developed two straight lines or rely on curve matching. Curve-matching methods are subjective and involve errors due to personal judgment. A very long duration pump test is required in order that the second straight line is developed. In many cases, the first straight line is not developed at all, especially when the observation well is at a greater distance from the pumped well. In this paper, a derivative-based robust optimization method has been proposed for the identification of aquifer parameters (transmissivity, T and storage coefficient, S) and r′ from the drawdowns observed at an observation well. It returns unbiased estimates of the parameters (T, S, and r′) even with a poor initi...