An Approach to Inundation Simulation in Large River Basins Using the Triangle Finite Difference Method

Abstract

Disastrous flooding and inundation events have drawn much attention in regional sustainable development due to extensive life loss and property damage they have caused. To support river basin management practice, it is necessary to simulate flood inundation such that associated risks can be integrated into decision-making processes. Flood inundation is generally simulated by the 2-dimensional Saint Venant equations (2D SVEs), in which inertia terms are neglected in most cases, particularly in large floodplains. In this study, a diffusive wave model discretized by an implicit numerical scheme of the irregular triangle finite difference method (TFDM) was developed to examine the effect of arbitrary inner and outer boundaries within a floodplain. A case study has been conducted in the Fuefuki River basin in central Japan. Comparisons with simulation using complete 2D SVEs are made in this study. Results indicate that both the diffusive wave model and its TFDM numerical scheme are effective and accurate in the simulation of flood inundation.

Keywords: Inundated area, inundated water depth, inundation simulation, irregular triangle mesh, St. Venant equation