Research On Zonation And Management Measures Of Flood Risks In The Levees-protected Area

Floods are one of the common natural disasters in China. Flood disasters seriously threaten people’s lives and property safety, block sustainable development of national economy. River dikes are important parts of a flood control system. They are the final barrier to prevent flooding. However, the energy of the flood is gathered while the dikes prevent flooding. The catastrophic flood caused by embankment outburst may result in a devastating disaster. Flood risk zoning is one of the non-engineering measures for reduction of flood losses. It is significant for building up the public awareness of flooding, promoting scientific decision-making of flood control, regulating the development and management of floodplains and carrying out flood insurance.Thus this paper studies flood risk distribution of dikes protected areas using index system combined with the spatial analysis of ARCGIS. Finally, appropriate risk management strategies are developed.The main research results are summarized as follows:(1)Flood risk assessment index system. Indices system of flood risk assessment is built for dikes protected area based on flood risk analysis theory and key characteristics of flood risk. The main indices of flood risk consist of the number of flood inundation, flood arrival time, maximum inundation and maximum submerged flow rate. The main indices of vulnerability of affected body include population density, GDP density, household density, cultivated area density and roads density. Flood frequency impact on flood risk is not considered due to the same number of the study area affected by flooding and flood inundation.(2)Flood risk zoning.Liao River from Shifosi to the mouth of Liuhe River is taken as the case study. Base on flood risk assessment indices system, the quantity of flood risk indices are obtained from overlay analysis based on flood risk assessment indices system using ArcGIS9.2and SPSS software. Then flood risks are classified into five levels. Finally, flood risk zoning map is finished according to the flood risk levels. The results show that:the highest degree of flood risk are mainly distributed in Sanmianchuan town and Taotun Region; High-risk areas, medium-risk areas and low risk areas are mainly located in Gongzhutun Town and Dongsheshanzi Region; The lowest level of flood risk areas are mainly distributed in Xincheng street due to the outburst of Juliuhe vulnerable spot. (3)Flood risk management strategies. Flood risk management strategies are proposed from the combination of the results of flood risk zoning and flood inundation characteristics. Different measurements are taken according to different flood risk levels in study area. Taken Hanjiawo vulnerable spot as an example, it is assumed that once-in-200-year flood occurs. The emergency response to outburst of the vulnerable spot is proposed based on the analysis of flood inundation characteristics (flood arrival time, maximum flow rate, flood inundation, flooding area, etc.).