An algorithm for coupling 1D river flow and quasi 2D flood inundation flow

摘要

Flood inundation simulation with a coupled one-dimensional full equation river flow model and quasi two-dimensional model for flood plain flow is presented. The inundated area is discretised into triangular cells derived from a triangulated irregular network type of digital elevation model. The triangular domains are treated as cells having horizontal ground levels. The water surfaces in the inundated cells are also assumed to be horizontal. Inter-cell flood water movement based on a uniform flow formula and the principle of mass conservation is used to predict the dynamic wetting and drying of cells. These equations are solved implicitly with the discretised river flow equations using the Gauss elimination method. Solution algorithms are proposed that reduce the computational efforts required to solve the resulting large and highly sparse system of equations.