A 1D-2D Coupled Numerical Model Based on Godunov Scheme for Levee-breach Flood Simulation

A 1D-2D coupled numerical model is developed based on Godunov scheme to simulate levee-breach flood in order to better understand the risk of levee-breach flooding. The Harten-Lax-van Leer (HLL) approximate Riemann solution is used in the 1D model for better simulating complex open channel flows occurred in mountainous rivers, and TVD-MUSCL format and the Hancock format are also applied to achieve second-order accuracy in space and time. The 2D model uses the Roe’s approximate Riemann solver in the calculation of flow flux based on an unstructured finite-volume method. The 1D and the 2D models are linked through the weir equation to quantify flow exchange. The coupled model can be used to accurately simulate 1D and 2D water flows, which has been tested with a classical numerical case. Finally, the coupled model has been successfully applied in dealing with possible flooding event due to levee breach in the Shu River, located in the Yishusi basin, Shandong Province, China. The simulation results can be directly used for flood risk mapping, and provide valuable information for all relevant flood-preventing departments.