北京“7·16”暴雨诱发地质灾害成因分析

从2018年7月16日北京暴雨过程雨情和地质灾害灾情出发,介绍了此次过程的地质灾害气象预警及检验;并基于北京区域地质灾害易发度信息,结合多源融合定量降水估测(QPE)驱动CREST水文模型模拟径流量与土壤湿度特征、过程雨强特征,分析了北京本次地质灾害气象成因。结果表明,北京北部和西部处于地质灾害中、高易发区,区(县)小时累计面雨量达到50 mm以上易发生灾害,降水持续24 h后是地质灾害的高发时段,灾害常发生于雨强较大峰值后的15 h内;基于雨强-降水持续时间推求的地质灾害致灾临界雨量阈值对北京地区地质灾害气象预警有一定的借鉴意义;基于水文模型的北京区域径流量、坡面径流深、土壤湿度等水文过程要素模拟对预警也有较好的指导意义。

Cause Analysis of the Geological Hazards Induced by the 16 July 2018 Rainstorm in Beijing

The heavy rainfall occurred on 16 July 2018 in Beijing resulted in a series of serious hazards such as urban water logging and collapse hazards. Starting with the analysis on the features of rain regime and its associated geological hazard situations, this paper mainly analyzes and summarizes the forecast and verification on the early warning of meteorological geological hazards for this kind of extremely intense rainfall. Based on the detailed information of geological hazards, this study further analyzes the causes of geological hazards in Beijing by combining the characteristics of rainfall intensity, soil moisture and the runoff evolution (derived from the CREST model driven by quantitative precipitation estimation data). The results indicate that the northern and western parts of Beijing are areas characterized by the mid- and high-risk susceptibility degree, the accumulated area-rainfall beyond 50 mm is prone to result in the occurrence of geological hazards and the occurrence time is during the next 15 h after the high peak of precipitation. Based on the rainfall intensity and precipitation duration, the threshold of critical rainfall of geological hazards can be derived as a reference for geological hazard meteorological forecast in the area. The simulation of hydrological process elements such as runoff, depth of overland flow, and soil moisture of hydrological model also has a good guiding significance for early warning of meteorological geological hazards in Beijing.