北京市"23·7"强降雨山洪泥石流灾害特征及成因机制分析OA

From July 29 to August 2,2023,Beijing experienced the most extreme rainfall event since systematic meteorological records began,triggering severe basin-wide flooding in the Beijing-Tianjin-Hebei region.Beizhaotai Village and Hantai Village in Liucun Town,Changping District,located in mountainous gully areas,were particularly hard-hit,experiencing typical debris flow and flash flood disasters,respectively.This study relies on multi-rotor UAV oblique photography technology to rapidly acquire high-precision topographic data and high-resolution imagery of Beizhaotai Gully and Heishigang Gully.Combined with field investigations,a systematic comparative analysis was conducted from the perspectives of topographic and geomorphic characteristics,loose material supply conditions,disaster formation models,and motion parameters.The results indicate that Beizhaotai Gully,with its abundant loose material reserves and open gully terrain conditions,formed a more destructive debris flow disaster.Its typical characteristics include:a fluid density of 1.31t·m-3,the formation of a fan-shaped accumulation at the gully mouth,burial-type damage to houses,material sources primarily from slope erosion,landslides,and channel deposits,exhibiting typical solid-liquid two-phase flow movement.In contrast,Heishigang Gully,due to the lack of loose material supply,steep and narrow channel,and large longitudinal slope,exhibited a typical flash flood disaster.Its characteristics are:fluid density close to clear water(1.011 t·m-3),no fan-shaped accumulation at the gully mouth,houses damaged by scour and erosion,material sources limited to sporadic gravel within the channel,and movement patterns dominated by bed load transport without forming a continuous transport belt.This study reveals the core differences and formation mechanisms of the two types of disasters,providing an important scientific basis and technical reference for disaster type identification,risk assessment,and the construction of prevention and control systems in similar mountainous geomorphic units under heavy rainfall conditions.