Shikha Saxena

A stream-aquifer subsurface seepage model is developed to estimate fluctuations in the water table in an unconfined sloping aquifer which receives subsurface seepage from adjacent water bodies and time-varying vertical recharge. The groundwater flow is approximated by a nonlinear advection-diffusion equation subjected to time-dependent boundary conditions. Two numerical schemes namely Mac Cormack scheme and Du Fort Frankel scheme are used for solving the nonlinear flow equations. A Model is developed by solving the nonlinear Boussinesq equation using the Laplace transform technique. The combined effects of bed slope, stream rise rate, and vertical recharge are demonstrated using an illustrative example. To assess the validity of linearization, numerical solutions are compared with analytical solutions using an extensive value of aquifer parameters. Simulation is done using hypothetical data and results are compared with the previous literature. The results indicate that the approximate analytical solution agrees with the numerical solution for bed sloping angle within the range – 5 deg to 5 deg