A preliminary development of a coupled surface and subsurface flow model for swale system

Abstract

This study presents the preliminary stage of the development of a conjunctive surface-subsurface model for simulating the flow in a swale. The surface flow is modelled by one-dimensional dynamic wave equation. To improve accuracy, a third-order numerical scheme is used to solve the advection terms in the dynamic wave model. Meanwhile, the subsurface flow is modelled as one-dimensional vertical flow through nondeformable porous media without air compression effect. At preliminary stage, the surface and subsurface model are verified separately. The surface model is verified against the experimental data of surface runoff from a simulated rainfall. The surface model showed promising performance in terms of the reproduction of surface hydrograph. The overall discrepancy between the experimental and numerical model result in the reproduction of the hydrograph discharge is around 14%. For the subsurface flow model, the vertical moisture profile of the soil is verified against Philip’s analytical solution. The moisture profile obtained from the numerical model shows 100% agreement with Philip’s solution.