"23·7"强降雨影响下泥石流特征及成因分析
Analysis of characteristics and causes of debris flows under the impact of"23·7"rainstorm:A case study of Nan'an Basin in Nanjiao township,Fangshan district,Beijing
摘要
Abstract
[Objective]In view of the still limited research on the cause analysis and disaster-causing mechanisms of debris flows driven by extreme rainfall in northern mountainous areas,this study took the"23·7"debris flow in the Nan'an Basin,Nanjiao township,Fangshan district,Beijing as an example to reveal the coupled topographic,source,and rainfall conditions and the disaster-causing mechanisms,thereby providing a basis for disaster prevention and mitigation in similar regions.[Methods]Combined with rainfall monitoring data,field investigation and laboratory tests were adopted in this study.The particle size distribution,uniformity coefficient,and curvature coefficient of loose source sediments in debris flow gully were emphatically analyzed,and the causative conditions and disaster-causing mechanisms of debris flows were further clarified.[Results]The disaster-causing mechanism of the"23·7"debris flow in Nan'an Basin presented a triple coupling effect of topographic facilitation,source sediment supply,and hydrodynamic triggering.1)The main gully of Nan'an Basin was characterized by large longitudinal slope,well-developed branch gullies,and flat-wide gully morphology,which led to concentrated and rapid confluence and easy formation of high flood peak discharge,forming the topographic foundation for debris flow initiation and transportation.A large number of loose deposits dominated by gravelly soil were distributed in the gullies with poor gradation and weak inter-particle bonding,which constituted the material foundation for debris flow occurrence.2)This disaster was classified as a dilute,gully storm-type,coarse clastic debris flow.All indicators of the extreme heavy rainfall during the"23·7"event far exceeded the triggering thresholds of debris flows in Beijing.The combination of short-duration intense rainfall and saturated soil significantly reduced the shear strength of the source sediment and generated strong scouring and erosion capacity,which directly triggered the debris flow.[Conclusions]The disaster-causing mechanisms of debris flows in northern mountainous areas differ markedly from those in southwestern China.The source sediment is predominantly loose debris previously accumulated in gullies,the hydrodynamic condition is extremely short-duration intense rainfall,and the flow type is a coarse-debris-dominated dilute debris flow.Such debris flows occur only during extreme rainfall events and are highly episodic.关键词
"23·7"强降雨/泥石流/灾害特征/成因分析/南安流域Key words
"23·7"rainstorm/debris flow/disaster characteristics/cause analysis/Nan'an Basin分类
资源环境引用本文复制引用
刘欢欢,田磊,蔡强国,翟淑花,冒建,于家烁.."23·7"强降雨影响下泥石流特征及成因分析[J].中国水土保持科学,2026,24(3):42-50,9.基金项目
国家自然科学基金"黄土坡面细沟形态与土壤再分布空间特征的耦合机制研究"(41977069),"黄土丘陵沟壑区坡面侵蚀过程对临界坡长的响应机制"(52179071) （41977069）
北京市自然科学基金项目"7.29极端降雨下北京西山矿渣型泥石流启动条件及演化过程研究"(8242010) （8242010）
北京市科技计划项目"北京暴雨灾害防灾减灾韧性空间规划提升关键技术研究与示范应用"(Z241100009124013),"山洪泥石流复合灾害综合预警指挥模式研究与示范"(Z251100004525022) National Natural Science Foundation of China"Coupling Mechanism of Rill Morphology and Spatial Characteristics of Soil Redistribution on Loess Slopes"(41977069),"Response Mechanism of Slope Erosion Process to Critical Slope Length in the Loess Hilly-Gully Region"(52179071).Beijing Natural Science Foundation Project"Study on Initiation Conditions and Evolution Process of Slag-Type Debris Flow in Beijing Xishan under Extreme Rainfall on July 29"(8242010).Beijing Science and Technology Plan Projects"Research and Demonstration Application of Key Technologies for Improving Resilient Spatial Planning for Disaster Prevention and Mitigation of Beijing Rainstorm Disasters"(Z241100009124013),"Research and Demonstration of Integrated Early Warning and Command Mode for Compound Disasters of Flash Floods and Debris Flows"(Z251100004525022) （Z241100009124013）
