四川省汶川县绵虒镇小流域泥石流危险性评价

2013年7月10日汶川县绵虒镇持续性暴雨引发岷江小流域内的泥石流群事件,使得岷江堵塞、公路摧毁和居民受灾,造成巨大经济损失和人员伤亡。经过野外实地调查、遥感影像解译及地形数据处理,首先对流域内8条重点泥石流沟运用模糊综合评判的方法进行了流域内的泥石流危险性评价,得出研究区8条泥石流的危险性结果为:瓦窑沟、新店沟、苏村沟3条泥石流沟为低危险,安家沟、草坡磨子沟、华溪沟3条泥石流沟为中危险,大溪沟、簇头沟2条泥石流沟为高危险。其次,选择危险性较高的簇头沟在与实际降雨频率相同的条件下运用FLO-2D软件进行数值模拟,重现泥石流暴发现状,得出其堆积扇危险特征,最后对模拟结果进行验证,作出危险性评价,得到危险性分区图。经统计计算得出簇头沟堆积扇中,高危险性面积占61%,中危险性面积占19%,低危险性面积占20%。该危险性评价对泥石流风险评估、预警预报、工程治理工作和危险范围分区可提供更有效的参考依据。

Hazard Assessment of Debris Flow in Small Watershed of Miansi Town,Wenchuan, Sichuan Province

The massive debris flows of the Minjiang River small watershed triggered by persistent rainstorm blocked Minjiang River, destroyed road and affected residents, causing enormous economic loss and casualties on July 10, 2013 in Miansi town, Wenchuan county. In this paper, the risks of debris flows in eight main debris flow gullies were assessed via fuzzy comprehensive evaluation based on field investigation, remote sensed imagery interpretation and terrain data processing. Wayao gully,Xindian gully and Sucun gully are of low risk;Anjia gully, Caopomozi gully and Huaxi gully are of medium risk, Daxi gully and Cutou gully are of high risk. Furthermore, Cutou gully which is of high risk was simulated under the actual rainfall frequency using FLO-2D. The outbreak scale of debris flow and the risk characteristics of deposition fan were obtained. Finally, the simulation results were verified, and hazard zoning map was made through the risk assessment. According to statistical calculation, the area of high risk zone accounted for 61% of the deposition fan area of Cutou gully, medium risk zone 19%, and low risk zone 20%. The risk assessment in the present paper offers a reliable reference for debris flow hazard assessment, disaster forecasting, engineering treatment and hazard zone partition in the study area.