A hybrid shallow water approach with unstructured triangular grids for urban flood modeling

Abstract

Classic shallow water equations (SWEs) and their various simplified approaches provide the theoretical basis for urban flood modeling. Aiming at the limitations of the local inertial approach (LInA), this paper proposes a hybrid approach that combines the LInA and classic SWEs to eliminate the errors caused by LInA. Results show that the hybrid approach can reduce the error from 7% to 1.5%, with slightly reduced computation efficiency in the dam break case. In the urban flood case, the hybrid approach can reduce the relative error on flood depth from 50% to 20% in a few grids, while the relative error on flood velocity is improved from 60% to below 30%. The hybrid approach proposed here can provide a practical strategy to eliminate the errors caused by the inherent defects of the simplified approach and still maintain the computation efficiency.