Study on Risk Assessment and Early Warning of Flood-Affected Areas when a Dam Break Occurs in a Mountain River

Under the influence of extreme weather conditions or other unfavorable factors, if a dam break occurs in a mountain river, it will cause a great number of casualties and property losses in the affected downstream areas. Usually, early warning of the affected areas downstream of the dam depends mainly on qualitative evaluation and cannot be quantitatively evaluated. Based on the authors' calculation of floods for many years, this study presents a quantitative assessment method for flood risk. The Ertan Hydropower Station in Southwest China and the flood-affected areas were chosen as the object of this study. Based on field surveys, research literature data, and the authors' calculations, the basic data of the Ertan Hydropower Station and the calculation results of the dam break were obtained, and 35 representative flood-affected areas were selected to study risk assessment and early warning. The fuzzy analytic hierarchy process (FAHP) was used to build a mathematical model for quantitative analysis. The population, flood arrival time, flood level, evacuation time, and local GDP (Gross Domestic Product) were selected as five typical evaluation factors. Finally, this study calculated and counted the risk level of 35 representative flood-affected areas, and the study results were applied to Quxue and Guanmaozhou Hydropower Station.