Aquifer parameter identification and interpretation with different analytical methods

Abstract

Aquifer tests yields estimations of hydrogeological parameters through suitable analytical models from field data recorded as drawdown variations by time or distance. In practice, most often a single model is adopted with a set of assumptions, and unfortunately, field data deviations from the model types curves are not considered in interpretations. This is a rather mechanistic approach which implies assumptions that the aquifer is geologically homogeneous and isotropic. Such an approach cannot be true because within the aquifer test area, there may appear heterogeneities and anisotropies which hinder the application of a single model. It is, therefore, necessary to try several available models for the same aquifer test data, in order to extract possible variabilities observation wells at different distances and directions. This paper presents an analysis of an aquifer test in a thick alluvial valley in Pakistan. The aquifer consists of extremely heterogeneous sediments. Different approaches including the Theis, Jacob, Hantush, and Singh analytical models; are sued to analyse the drawdown data from several observation wells.