A Novel Semi‐Analytical Solution of Over‐Damped Slug Test in a Three‐Layered Aquifer System

Abstract

The slug test has been commonly used to estimate aquifer parameters. Previous studies on the slug test mainly focused on a single‐layer aquifer. However, understanding the interaction between layers is particularly important when assessing aquifer parameters under certain circumstances. In this study, a new semi‐analytical model on transient flow in a three‐layered aquifer system with a partially penetrating well was developed for the slug test. The proposed model was solved using the Laplace transform method and the Goldstein‐Weber transform method, where the semi‐analytical solution for the model was obtained. The drawdowns of the proposed model were analyzed to understand the impacts of the different parameters on the drawdowns in a three‐layered aquifer system. The results indicated that groundwater interactions between the layers have a significant impact on the slug test. In addition, a shorter and deeper well screen as well as a greater permeability ratio between the layers creates a greater interface flow between them, leading to a higher drawdown in the slug test. Finally, a slug test in a three‐layered aquifer system was conducted in our laboratory to validate the new model, which indicated that the proposed model performed better in the interpretation of the experimental data than a previous model proposed by Hyder et al. (1994). We also proposed an empirical relationship to qualitatively identify the errors in the application of single‐layer model for the analysis of response data in a three‐layered aquifer system.