Hydrological components of groundwater recharge in leaky aquifers adjacent to semipervious streambank: analytical study.

Abstract

Groundwater resources can be artificially augmented by managed aquifer recharge especially in arid and semi-arid areas. Unlike most of the existing results which focus only on impervious aquifer base and assume perfect hydraulic connection between aquifer and adjacent stream, the present study addresses the recharge process in a more realistic case of leaky aquifer interacting with semipervious streambank. The mathematical model relies on 2D linearized Boussinesq equation with Robin boundary condition accounting for hydraulic resistance owing to semiperviousness of the streambed. The method of Green's function offers an integral representation of hydraulic head in semi-infinite aquifer domain in response to time-varying recharge from a rectangular basin. Hydrological components of groundwater recharge are derived taking into account volumetric rates of leakage, mound storage, and outflow to adjacent stream. Hypothetical test cases illustrate how sum of these components exactly counterbalances the volumetric rate of recharge received by the aquifer at each instant of time, and this is in full conformity with the expected mass balance at aquifer scale. The most influential parameters affecting the model outputs are identified through sensitivity analysis. Furthermore, interaction of pumping wells with groundwater mound is examined. Performance of the present results is assessed against numerical counterparts from finite element method, and extremely good agreement is found for temporal mound peaks.