降雨激发滑坡型泥石流转化特征和阈值研究——以江西大吉山2019.6.10灾害为例

Rainfall Threshold and Evolution Characteristics of Landslide-Debris Flow Induced by Rainfall--A Case Study of the"June 10,2019"Disaster in the Dajishan Area,Jiangxi Province

滑坡向泥石流转化后形成更大灾害,以2019年6月10日江西省大吉山流域发生的2类11条滑坡型泥石流为例,通过影像识别、现场调查、GIS空间分析和数理统计等方法对2类滑坡型泥石流的地形特征、物源特征、转化特征和降雨阈值进行分析。结果表明:①间接转化型是滑坡堆积物先堆积沟道后经汇水启动形成,直接转化型是滑坡堆积物在下滑过程中直接转化形成;②参与转化的物源为滑坡堆积体,滑坡体以浅层小型、“宽薄型”为主;③2类转化型泥石流在流域面积、沟道弯曲度、纵比降等指标上有明显界限,该指标可用于快速识别2类泥石流;④利用现有预测模型计算该区域本次滑坡型泥石流降雨阈值,该降雨阈值可为该地区泥石流灾害的预报提供理论参考。

On June 10,2019,an intense rainstorm swept Dajishan in Jiangxi Province of China,inducing landslides and debris flows.Image interpretation,field survey,data statistics and GIS spatial analysis were used to study the evolution process and rainfall threshold of landslide-debris flow.The results show that:①the indirect transformation type is that the landslide first accumulates in the channel and then the sediment starts to form a debris flow,and the direct transformation type is that the sediment is directly transformed to form a debris flow during the sliding process of the landslide.②The landslides involved in the transformation are all small shallow landslides,and the landslide shape is mainly″wide and thin″.③The two types of debris flows evolved from landslides are quite different in terms of formation process,topographic features and provenance thickness.④Using the forecast model,the forecast thresholds of debris in this area are given,which provides theoretical reference for the forecast of disasters in this area.