泥石流风险区划方法及其应用——以四川西部地区为例

以川西地区60个县(市、区)为基本评价单元,在自然灾害风险评估基本框架下,基于国内现有区域泥石流危险度和易损度评价方法,结合研究区实际,对区域泥石流危险度8项评价指标中的3项进行了调整,用年平均降雨量取代洪灾发生频率,用流域相对高差取代≥25°坡地面积百分比,在多雨地区雅安市所属的8个评价单元中用年平均暴雨日数取代大雨日数。通过采集研究区15 a来自然、经济、人口和土地利用的基础数据,运用ArcGIS 9.0的成图技术,得出川西地区泥石流危险度、易损度和风险区划系列图。研究表明,川西地区泥石流高风险区共24个县(市、区),是四川省泥石流风险的重点防范区。

Application of Debris Flow Risk Zonation: An Example of West Sichuan

Taking 60 counties and districts of west Sichuan as the basic assessment units, under the international outline of risk assessment for natural hazards, based on the existed assessment method of debris flow hazard and vulnerability, incorporated with the surroundings of study area, this paper alters 3 assessing factors of the original 8 factors, i.e. using the mean annual precipitation to replace the occurrence frequency of floods, substituting the regional relief for the percentage of slope land >25?, using the days of mean annual rainstorm with 50 mm to replace the days of mean annual rainfall with 25 mm. By collecting a number of data related natural, economic and population of the study area during recent 15 years, as well as the data processing and analyses with the mapping technique of ArcGIS 9.0, this paper has obtained respectively the zonation maps of debris flow hazard, vulnerability and risk. Studies indicate that there are totally 24 counties with high risk, accounting for 40% of the total, and occupied land area of 65 714 km², accounting for 20.58% of the total. The moderate risk counties are 33 with land area of 241 747 km², separately, counting for 55% and 75.71%. Obviously, the west of Sichuan is the vast area with moderate and high risk of debris flow, is also the main area for debris flow risk mitigation in Sichuan.