白龙江武都区段泥石流分布规律及其危险性评价

Debris flow distribution law and risk analysis in Wudu section of Bailong River

基于遥感解译和实地调查,白龙江流域武都区段共发育329条泥石流沟。根据地形地貌、物质条件、外部激发因素三大孕灾条件,选取高程、坡度、岩性等9个孕灾因子,基于ArcGIS平台,分析研究区内泥石流分布规律,采用信息量法进行泥石流危险性评价。分析结果表明:(1)地形地貌上,研究区泥石流主要分布在1800~3000 m和NDVI值为0.2~0.4的范围内,其优势坡度分布区间为15°~35°。(2)物质条件上,泥石流大量分布在地震动峰值加速度为0.2g的范围内,且在以千枚岩、板岩为主的软弱-坚硬中厚层-厚层板岩、碎屑岩组区内,与距断层距离呈负相关分布。(3)外部激发因素主要分布在1 h最大降雨量为36~40 mm区域内,与距河流、道路距离呈负相关分布。(4)运用信息量法对泥石流做危险性评价,得到泥石流危险性分区图,在中度、高度、极高度危险范围内的泥石流面积分别占总泥石流面积的21.77%,32.94%,31.49%,且较高等级危险区主要分布在白龙江的北岸。应用ROC曲线验证评价结果,AUC=0.737,表明评价结果有较高的准确度和可靠性。

Based on remote sensing interpretation and field investigation,there are 329 debris flows developed in the Wudu section of Bailong River Basin.According to the three major disaster-pregnancy conditions of topography,material conditions and external excitation factors,9 disaster-pregnancy factors such as elevation,slope,and lithology were selected.Based on ArcGIS platform,the distribution law of debris flow in the research area was analyzed and the debris flow risk was assessed by using information model.The analysis result showed that:(1)Debris flows in the study area were mainly distributed in the elevation range of 1800~3000m and NDVI value of 0.2~0.4 in terms of topography,and their dominant slope distribution range were 15°~35°.(2)In terms of material conditions,a large number of debris flows we re developed in the range of the peak acceleration of ground motion of 0.2g,and mainly distributed in the soft-hard and medium-thick layer-thick layer slate and clastic rock formations mainly composed of phyllite and slate,while the areas of debris flow were negatively correlated with the distance from the the faults.(3)External excitation factors were mainly distributed in the area with the maximum rainfall of 36~40 mm per hour.And it was negatively correlated with the distance from the rivers and roads.(4)The risk assessment on debris flow was done by information method and the risk zoning map was obtained.Results showed that the debris flow area in the medium,high and extremely high risk range accounted for 21.77%,32.94%and 31.49%of the total debris flow area,and the high-level danger zone was mainly distributed on the north bank of Bailong River.The ROC curve was used to verify the evaluation result,and AUC was 0.737,which means the evaluation result is accurate and reliable.