A TRANSIENT MODEL FOR SHALLOW GROUNDWATER TABLE EVOLUTION IN AN UNCONFINED SLOPING AQUIFER

This study presents a new numerical model for transient shallow groundwater table in an unconfined sloping aquifer. The theory for groundwater table evolution is the hydraulic groundwater theory, or called Dupuit-Boussinesq theory. The relaxation approach is applied for numerically calculating the nonlinear advection-diffusion equation with the help of the Godunov based wave-propagation algorithm. The transient numerical model is verified with the steady-state solution. We performed two case studies considering variable rainfall patterns and variable hydraulic conductivity. The resultant hydrographs of outflow discharges and groundwater tables at the downstream outlet are obtained. The results verify that our transient model is practical for modeling motion of thin groundwater table in an unconfined sloping aquifer.