A finite volume approach for shallow water flow accounting for high‐resolution bathymetry and roughness data

This study presents a finite volume hydrodynamic model for shallow water flow that computes on a coarse grid, but accounts for high‐resolution bathymetry and roughness variations on a subgrid. The detailed information can be incorporated by using the assumption of a uniform flow direction and a uniform friction slope within a part of a coarse‐grid cell. It is shown in two examples that the results of coarse‐grid simulations become as good as high‐resolution results, but at much lower computational cost.