EFFECTS EVALUATION OF URBANIZATION ON FLOOD RISK IN THE YANGTZE RIVER DELTA

Six urbanization typical areas namely Lixiahe,Qinhuaihe,Wuchengxiyu,Pudongpuxi,Hangjiahu and Yongcaopu were selected in the Yangtze River Delta and 1991,2001 and 2006 were selected as the representative years of different urbanization stages in the study.The index system-based assessment method was used to reveal the effect of urbanization on flood risks.Risk evaluation index system was established based on the flood disaster formation mechanism,and the analytic hierarchy process was utilized to determine the index weights.Then,the hazard,exposure,vulnerability and composite risk of flood disaster were evaluated.The results showed that the flood hazards of 6 areas presented an increasing trend in the process of urbanization,and the increasing trends of hazard-affected bodies exposed in flood stricken area were especially obvious.Though the vulnerabilities of 6 areas presented an decreasing trend owing the enhancement of flood prevention ability,the composite flood risks of 6 areas tended to be exacerbated in whole,which would pose a serious threat to urban sustainable development.Finally,some flood risk management countermeasures for urbanization areas in the Yangtze River Delta were put forward based on the evaluation results.