Development of Flood Management Decision Support Framework Using Nomographs Based on Multi-dimensional Hydrologic Models

Abstract

Recently activities in the rivers are rapidly increased in our country, the demand for information about river flood also surged. So decision makers of flood control organization have to consider more needs and more complex environmental aspects. Conventionally flood forecast in South Korea means forecasting the time and the amount of flood peak, but we need new decision support framework which can suggest the possibility of inundation, deciding dam release amount and the weir operational water level. In this study, several tools(runoff estimation, inundation simulation, distributed rainfall-runoff model using rain radar data, the effect of storm direction) are used to simulate more than 12,000 flood situations. Based on these results, we set threshold discharge amount Qth which cause the specific flood events like inundation. And using threshold discharge, the decision makers can decide dam release amount and weir operation plan. This study suggest the threshold Q nomograph just using rainfall and dam release amount. Also this study suggest nomograph to decide dam release amount considering heavy rainfall announcement. And using estimated Q, This study suggest nomograph which can be used as decision making tools for floodplain inundation considering Gongju weir operational water level. Finally GUI program was made to estimate flood situation easily just selecting rainfall, dam release amount and weir operational water level. And the I-D-Q curves are applied to compare flood forecasting accuracy. These multi-dimensional hydrologic model based Nomographs and GUI program are more helpful to local government in charge of the flood prevention.