甘肃舟曲三眼峪沟泥石流的形成条件与发展趋势

Conditions leading to the destructive debris flow at the Sanyanyu Gulley and its occurrence trend

2010年8月8日,舟曲县城北侧三眼峪沟和罗家峪沟暴发的特大山洪泥石流,给舟曲县城人民生命财产造成了巨大损失。本文基于现场调查,分析了三眼峪沟泥石流的形成条件和未来泥石流的发展趋势。调查发现,独特的地形条件、极其丰富的固体物质储备和极端降雨条件,导致了"8.8"特大泥石流灾害。崩塌堆积体是三眼峪沟泥石流固体物质的最主要来源,受"8.8"泥石流的影响,沟内堆积物的稳定性进一步降低,一旦有强降雨发生,该沟很可能再次发生泥石流,并且泥石流的规模和活动性可能进一步增强。

Debris flow occurred on August 8, 2010 at the Sanyanyu Gulley and Luojiayu Gulley, Zhouqu County, Gansu Province caused the county a big loose of both lives and properties. In this paper, conditions leading to the debris flow in Sanyanyu Gulley and trend of debris flow in the gulley are analyzed based on a site investigation immediately after the disaster. It is found that the debris flow was resulted from the combination of an unique landform of the gulley, extremely abundant loose materials in the gulley and usual rainstorm. Source materials of the debris flow were mainly from rackfall deposits in the gulley. Because stability of source materials in the gulley has been reduced as a result of strong erosion of the ＂8.8＂ debris flow, it is believed that it is very likely that debris flow will occur in gulley again and that its scale and intensity may become greater.