A numerical investigation of pumping-test responses from contiguous aquifers

作者：Rafini Silvain; Chesnaux Romain^*; Ferroud Anouck

来源：Hydrogeology Journal, 2017, 25(3): 877-894.

DOI：10.1007/s10040-017-1560-x

• Pumping tests
• Heterogeneity
• Hydraulic properties
• Derivative analysis
• Flow dimension

Adequate groundwater management requires models capable of representing the heterogeneous nature of aquifers. A key point is the theoretical knowledge of flow behaviour in various heterogeneous archetypal conditions, using analytically or numerically based models. This study numerically investigates transient pressure transfers between linearly contiguous homogeneous domains with non-equal hydraulic properties, optionally separated by a conductive fault. Responses to pumping are analysed in terms of time-variant flow dimension, n. Two radial stages are predicted (n: 2 - 2) with a positive or negative vertical offset depending of the transmissivity ratio between domains. A transitional n = 4 segment occurs when the non-pumped domain is more transmissive (n: 2 - 4 - 2), and a fractional flow segment occurs when the interface is a fault (n: 2 - 4 - 1.5 - 2). The hydrodynamics are generally governed by the transmissivity ratio; the storativity ratio impact is limited. The drawdown log-derivative late stabilization, recorded at any well, does not tend to reflect the local transmissivity but rather the higher transmissivity region, possibly distant and blind, as it predominantly supplies groundwater to the well. This study provides insights on the behaviour of non-uniform aquifers and on theoretical responses that can aid practitioners to detect such conditions in nature.

• 出版日期2017-5