Evaluation of pumping test data using analytical and numerical methods

Abstract

In this study, the well performance and near-well hydraulic conductivity are determined through analytical and numerical methods applied to water level data obtained from pumping tests. For this purpose, a well was drilled in an unconfined aquifer in Bursa Kucuk Sanayi region. In the well, several pumping tests, namely, step-drawdown test, recovery test and multirate pumping test were performed. Hantush-Bierschenk and Rorabaugh methods were applied to the data from step-drawdown tests and discharge-drawdown curves were obtained. On the other hand, recovery test and multirate test were performed to determine the hydraulic conductivity. MODFLOW software, which solves groundwater flow problems using method of finite differences, was used for numerical modeling. In MODFLOW, simulations of the pumping tests were made for various cases related to grid resolution and specific yield. The discharge-drawdown curve of MODFLOW was compared to those obtained from analytical solutions and a good correspondance was observed. In addition to this, multirate pumping test modeled in MODFLOW yielded a similar hydraulic conductivity as the analytical solution.