基于GIS-AHP集成的无资料小流域山洪灾害风险评价

Flash Flood Risk Assessment in Ungaged Small Basin Based on GIS and AHP Integrated Method

以清远市石坎河无资料小流域为研究区域,在采用综合单位线法和推理公式法得到100 a一遇设计洪峰流量的基础上,建立了一个包含洪峰流量、高程、坡度、土壤类型、人口密度、土地利用类型6个指标的山洪灾害风险评价体系,借助GIS-AHP方法实现无资料小流域山洪灾害风险区划。结果表明:(1)石坎河流域内山洪灾害风险等级较高的区域集中在河流中下游和沿河200 m范围内;(2)设计洪峰流量可以作为山洪灾害风险评价的重要指标;(3)集成GIS-AHP方法是无资料小流域进行山洪灾害风险区划有效且快速的方法。评价结果与流域实际情况吻合,可为全国绘制山洪灾害风险图提供借鉴。

This paper calculates the design peak discharge of 1% frequency flood in Shikan River Basin of Qingyuan City by using synthetic unit hydrograph and rational formula. Six assessment indexes are considered in order to establish flash flood risk assessment model,including design peak discharge,elevation,slope,soil types,density of population and land use types. GIS and AHP Integrated Method is applied to demarcate risk level in ungauged small basins. The results show that the higher risk area is concentrated on the midstream and downstream of the river and both sides of the 200 m range. Design peak discharge is an important index for a flash flood risk assessment. GIS and AHP integrated method is effective and fast to assess the flash flood risk in ungauged small basins. The evaluation results coincide with the actual situation of basins,which can provide a reference for the risk mapping of flash flood in China.