Coupled Surface–Subsurface Flow Modelling Using the GeRa Software

Abstract

Mathematical model and numerical methods for the solution of coupled surface–subsurface flow in GeRa software is presented. Coupling of surface runoff and subsurface flow models is accomplished using first-order exchange term. The arising nonlinear solver convergence issues are addressed in the article. In order to overcome these issues, approaches for handling the surface–subsurface flux expression are introduced. The proposed numerical model is verified and validated using benchmarks with reference solutions obtained in different codes as well as experimental results.