Numerical simulation of groundwater recharge from an injection well

This paper presents the numerical simulation of groundwater recharge from a point source, that is, injection well using Explicit Finite Difference Model (FDFLOW) and Galerkin Finite Element Model (FEFLOW). The proposed model aims at simulation of groundwater flow in two-dimensional, transient, unconfined aquifer for a chosen synthetic Test Case. These models are validated with reported analytical solutions for a test run period of 210 days. It is found that the FEFLOW model performed better than FDFLOW model in terms of conservation of mass and oscillations in numerical solutions. For simulation of recharge from an injection well test run period of 1500 days is considered. The accretion in groundwater volume from an injection well is analyzed. Further the effect of injection rate of a well and aquifer parameter is analyzed on model results. It is found that both the model solutions are highly sensitive to injection rate and moderately sensitive to transmissivity whereas the specific yield has negligible effect on numerical solutions.   Key words: Explicit Finite Difference Model (FDFLOW), Finite Element Model (FEFLOW), model validation, mass balance, courant number, sensitivity of models to recharge rate, transmissivity and specific yield.