基于情景分析的区域洪涝灾害风险评价——以巢湖流域为例

洪涝灾害是制约区域粮食安全和社会可持续发展的主要因子之一。在风险识别的基础上,从致灾因子、孕灾环境、承灾体等方面选取评价指标,建立评价指标体系。运用层次分析法确定指标权重,通过情景分析技术从降水、土地利用、人口、GDP等方面构建复合情景;应用GIS空间分析技术构建洪涝灾害风险评价模型,对巢湖流域洪涝灾害风险进行评价。研究结果表明:2020年巢湖流域洪涝灾害危险性由东南部向西北部减小;合肥市区的洪涝灾害易损性最大,和县的易损性最小。巢湖流域东南部洪涝灾害风险最大,西南部的大别山区风险较小,随着重现期的增大,流域的洪涝灾害风险也逐渐增大。模拟灾害发生的情景,并分析不同情景下的洪涝灾害风险,更能体现洪涝灾害的不确定性和变化性,为流域防洪战略决策研究提供科学依据。

REGIONAL FLOOD RISK ASSESSMENT BASED ON SCENARIO ANALYSIS——A CASE STUDY OF CHAOHU BASIN

Flood disaster is one of the main factors restricting regional food security and social sustainable development. The Chaohu Basin is suffering from frequent and severe floods. Floods often take place around rivers and plains, which indicates a higher risk of flooding in these areas. A lot of studies have been done in the field of flood disaster, including flood risk assessment. Methods of flood risk assessment mainly include probability statistics from the historical disaster data, hydrologic and hydraulic models and flood simulation, geo-spatial information technology, the index system, scenarios drivers as well as mathematical method. Based on risk identification, evaluation index is selected and evaluation index system is established from hazard factors, disaster environment and hazard bearing body in this paper. Evaluation indicators are mainly precipitation, terrain, river, flood, land use, population, GDP etc. Evaluation index weights are determined by using the analytic hierarchy process (AHP). Using the Pearson-Ⅲ model, Marko-CA model and ArcGIS spatial analyst tools, flood risk complex scenarios are proposed and presented from different return period precipitation, land use, population and GDP. Based on GIS spatial analysis technology, the analytic hierarchy process and spatial raster data, flood disaster risk assessment model is constructed to evaluate the flood risk in the Chaohu Basin. The results show that flood hazard distribution pattern is reduced from southeast to northwest. The plain area along the Yangtze River of the southeastern basin has the maximum risk. The vulnerability of flood is greater with greater return period. Economic vulnerability of Hefei City is the biggest, followed by Wuwei County but the He Countys vulnerability is smaller. The 30-year flood risk has a maximum of 4.37, the 50-year flood risk has a maximum of 4.49, and the 100-year flood risk maximum value is 4.65. The risk of flood disaster becomes greater with greater return period. Flood risk reduces from southeast to northwest in Chaohu basin in 2020. High risk is in southeast of the Chaohu Basin, and low risk areas are mainly distributed in Dabieshan mountain of southwest of the Chaohu Basin. With the increase of return period, flood disaster risk gradually increases. Through a comprehensive analysis on the influencing factors of flood disasters in the Chaohu Basin, the main causes underlying the flood disaster change is explored. Simulating disaster scenario and analyzing flood risk under different scenarios can reflect flood uncertainty and variability. It also can provide a scientific base for the policy making and implementation of flood prevention and mitigation designs.