Analytical solution for the catchment zone of a well located near a groundwater divide in a recharged semi-confined aquifer

An analytical solution is presented for delineating the catchment zone of a well located near a groundwater divide in a recharged aquifer. The analytical solution is derived for an infinitely wide, homogeneous, isotropic and uniformly thick semi-confined aquifer. It is shown that the shape and extent of the well catchment zone only depend on the distance to the groundwater divide and on the ratio of the well pumping and groundwater recharge rates. The catchment zone of a pumping well extends beyond the groundwater divide, such that the total area affected at the other side of the groundwater divide equals one half of the well-catchment area, and consists of a part from which groundwater is captured by the well and another part from which groundwater is flowing to the other side but bypassing the well. The amount of groundwater transfer involved equals half of the pumping rate. In case of an injection well, the catchment zone comprises the whole aquifer when the well is sufficiently close to the groundwater divide, and otherwise consist of an infinite but laterally bounded zone in the direction away from the groundwater divide. In both cases, the aquifer at the other side of the groundwater divide gains half of the well injection rate either directly by flow from the injection well or indirectly by capturing groundwater recharge from the other side of the groundwater divide. (C) 2014 Elsevier B.V. All rights reserved.