Development of a flood inundation model for extreme flood analysis

Two-dimensional flood inundation model and quantitative precipitation estimation(QPE) model were developed to evaluate the impact of levee failure for flood analysis. For improved areal rainfall estimation, cokriging technique was adopted to optimally merge radar reflectivity data into rain-gauges data by getting the better information of spatial variability of rainfall fields from weather radar and getting the better quantitative information from rain gauges. For the improved inundation model development, the mathematical formulation of the suggested model incorporates two-dimensional shallow water equations for flood inundation analysis. The developed model was applied to analyze the inundation flow from the levee break of Gamcheon river during the typhoon Rusa on October 31 through September 1, 2002. To verify the simulated results, wide range field surveys have been performed including the collection of GIS database, land use condition, flooded area, and flow depths. Velocity distributions and inundation depths were presented to demonstrate the robustness of the model. Simulation results have good agreements with the observed data in terms of flood level and flooded area. Methodologies considering radar-rainfall estimation, rainfall-runoff analysis and inundation analysis in this study will contribute to the establishment of the nationwide flood disaster prevention system