“23·7”强降雨对北京西山曹家坊泥石流隐患易发性影响

Influences of"23·7"heavy rainfall on the hidden danger of debris flow at Caojiafang,Beijing

探讨极端强降雨对于泥石流易发性的影响,为泥石流灾害预警与防治提供支持。以北京市曹家坊泥石流沟为研究区,选取泥砂沿程补给长度比、沿沟松散物储量、产沙区松散物平均厚度等因子,结合遥感手段参照《地质灾害危险性评估技术规范》,对研究区在“23·7”强降雨前后的泥石流易发性进行打分并评价。结果表明:泥沙沿程补给长度比、沿沟松散物储量、产沙区松散物平均厚度、河沟堵塞程度、河沟近期一次变幅等5项因子更易受到极端强降雨的影响;在冲於作用影响下,曹家坊泥石流沟的易发性由“低易发”升级为“中易发”,建议对淤积物源进行清理。

To explore the influence of extremely heavy rainfall on the susceptibility of mudslides,and provide support for early warning and prevention of mudslide disasters,this paper takes Caojiafang mudslide ditch in Beijing as the study area and selects 15 factors such as sediment recharge length ratio,loose material storage along the ditch,and the average thickness of loose material in the sand-producing area.The standardized scoring method is applied in combination with remote sensing to score the susceptibility and make comparisons of the mudslides before and after the heavy rainfall of"23·7"in the study area.The results show that 5 factors,including the length ratio of along-channel recharge,loose material storage along the gully,the average thickness of loose material in the sand-producing area,the degree of blockage of the gully,and the recent variation of the gully,are more susceptible to the influence of extreme rainfall.Under the decisive influence of the flushing effect,the susceptibility of Caojiafang mudslide gully is upgraded from"low susceptibility"to"medium susceptibility".The susceptibility of Caojiafang mudslide ditch is also upgraded from"low susceptibility"to"medium susceptibility"under the decisive influence of alluvial action.