2-D simulation of flow in a shallow aquifer stressed by surface reservoirs

A model is developed to evaluate nonsteady flow in a shallow aquifer affected by water loads in surface reservoirs. Following Terzaghi's concept of effective stress, the surface water load introduces an apparent source term accounting for the rate of the total vertical stress on the porous media. Solution of the flow equation is subject to measured values in time and space of: 1) piezometric heads; 2) pumpage and estimated recharge; 3) water loads in surface reservoirs; and 4) regional evapotranspiration. Boundary conditions involve time varying hydraulic heads, constant effluxes and impermeable segments. Finite elements simulations prove to be consistent with field test measurements and suggest a link between reservoirs loads and groundwater accumulation at their vicinity, thus indicating the obstruction of aquifer's drainage system.