Flood simulation using the gauge-adjusted radar rainfall and physics-based distributed hydrologic model

This paper reports of an investigation into flood simulation by areal rainfall estimated from the combination of gauged and radar rainfalls and a rainfall-runoff, model on the Anseong-cheon basin in the southern part of Korea. The spatial and temporal characteristics and behaviour of rainfall are analysed using various approaches combining radar and rain gauges: (1) using kriging of the rain gauge alone; (2) using radar data alone: (3) using mean field bias (MFB) of both radar and rain gauges; and (4) using conditional merging technique (CM) of both radar and rain gauges. To evaluate these methods. statistics and hyetograph for rain gauges and radar rainfalls were compared using hourly radar rainfall data from the Imjin-river , Gangwha, rainfall radar site, Korea. Then, in order to evaluate the performance of flood estimates using different rainfall estimation methods, rainfall-runoff simulation was conducted using the physics-based distributed hydrologic model, Vflo (TM). The flood runoff hydrograph was used to compare the calculated hydrographs with the observed one. Results show that the rainfall field estimated by CM methods improved flood estimates, because it optimally combines rainfall fields representing actual spatial and temporal characteristics of rainfall. Copyright (c) 2008 John Wiley & Sons, Ltd.