A two dimensional finite volume model for rain garden infiltration simulation

Urban groundwater recharge has become vitally important due to dramatic drop in groundwater levels, which seriously endangers the sustainability of these resources. A two dimensional FORTRAN code was developed based on finite volume approach to solve Richards’ equation. The model was tested with several soil textures such as sandy soil, sandy loam soil, Berino clay soil, and loamy soil. Three different boundary conditions such as Dirichlet, Neumann and free drainage, were used to simulate five test cases including one and two dimensional problems.In all cases the proposed two dimensional model showed an acceptable agreement with an analytical solution or with results obtained by well-known codes such as HYDRUS and RECHARGE.Eventually, two rain garden soil texture profile including layered and homogenous soil were compared in terms of their groundwater recharge capability. Comparing groundwater recharge by both rain gardens showed that layered rain garden lead to significantly more groundwater recharge.

Keywords:

Recharge , Groundwater , Stormwater Management , Richards’ Equation