北京菜食河流域四海—珍珠泉段泥石流特征与危险性评价

Characteristics and risk assessment of debris flow in Sihai-Zhenzhuquan section of Caishi River Basin, Beijing

中文关键词: 菜食河流域  四海—珍珠泉段  分区特征和形成条件  泥石流活动特征  危险性评价

英文关键词: Caishihe River Basin  Sihai-Zhenzhuquan section  zoning characteristics and formation conditions  activity characteristics of debris flow  risk assessment

中文摘要:

      北京菜食河流域延庆段曾发生多处泥石流事件，严重影响了当地人民的生产、生活。本文选取菜食河流域四海—珍珠泉段受灾严重、潜在经济损失最大的 17条沟谷为研究对象，在野外精细调查的基础上，应用GIS的大数据统计功能，统计研究各泥石流分区特征和泥石流形成条件、泥石流易发性和活动特征；选择了松散物质储量、沟岸平均坡度、汇水面积、相对高差、主沟长度、年平均降雨量和植被覆盖率共 7种评价因子，划分了泥石流危险性等级。结果表明:菜食河流域四海—珍珠泉段泥石流沟物源条件包括沟道冲洪积、坡残积、人类活动堆积和崩滑塌堆积体 4类，物源总储量达 1681.30×104 m3，平均厚度 1.01 m；暴雨洪峰流量整体较大，其中最小为 1.53 m3/s，最大为 31.63 m3/s；危险性评价结果显示流域两侧沟谷为低危险的沟 5条，中危险的沟 7条，高危险的沟 5条，其中，高危险泥石流沟严重威胁流域沿岸珍珠泉乡、四海镇沿河分布的村庄、道路，评价结果对延庆区开展小流域泥石流工程治理、防灾减灾具有重要科学意义。

英文摘要:

      Frequent debris flow events in the Yanqing section of Beijing’s Caishi River Basin pose significant threats to local communities and infrastructure. This study focuses on 17 gully systems within the Sihai-Zhenzhuquan segment, combining field investigations with GIS-based statistical analysis to evaluate debris flowcharacteristics, formation conditions, susceptibility, and activity patterns. A risk assessment framework was estab-lished using seven key parameters: loose material reserves (1681.30×104 m3), average slope gradient of gully banks(1.01 m), catchment area, relative elevation difference, main channel length, annual rainfall, and vegetation cover-age. Results indicate that debris flow source materials in the study area primarily consist of channel alluvium, slopedeposits, anthropogenic accumulations, and landslide deposits. Under rainfall scenarios with return periods of 50years (P=2%) and 5 years (P=20%), peak discharge rates reach 31.63 m3/s and 1.53 m3/s, respectively. Risk classifi-cation reveals five low-risk, seven medium-risk, and five high-risk gullies. High-risk gullies critically endangervillages and transportation networks in Zhenzhuquan Township and Sihai Town. These findings provide a scientificfoundation for targeted engineering mitigation and disaster reduction strategies in the Yanqing District.