安县雎水河流域泥石流特征及形成条件研究

Characteristics and Formation Conditions of Debris Flows in Jushui River Basin,Anxian County,Sichuan Province

雎水河流域位于四川省安县西北部,属于"5.12"汶川Ms 8.0级地震重灾区。地震发生后的5个汛期内,每年均有不同规模的群发性泥石流发生。其中以2013年7月9日的泥石流灾害最为严重,规模与灾情巨大,造成了惨重的损失。在对雎水河流域泥石流灾害现场调查的基础上,从泥石流形成的物源条件、地形地貌条件和水动力条件入手,以ArcGIS为平台,利用DEM数据,结合区域地质构造和地层岩性等信息,分析了泥石流的形成条件、分布特征及灾害特征。研究得出结论:1流域地形地貌为泥石流的形成和径流流通提供了极为有利的地形条件,固体松散物质补给量潜力巨大,为泥石流的形成提供了物源条件,大强度局地暴雨给泥石流的形成提供了强大的水动力条件。2研究区内泥石流主要分布在页岩等软弱地层区域以及断裂构造发育的区域,地形坡度陡、地形起伏度大的地区则更为密集。3流域内泥石流具有群发性、高频率、密度大、搬运能力强、崩滑流灾害相互叠加灾害效应放大的特征。

Jushui River is located at Northwest of Anxian County in Sichuan Province, which belongs to the epicenter area of the 2008 Wenchuan Earthquake. During the past five flood seasons, there are group-occurring debris flows with different scales every year at Jushui River. The debris flows happened on July 9 of 2013 is the most destructive, and has brought out huge damages to the area of Jushui River. In this paper, we discussed the characteristics, distribution and formation conditions of the debris flow in Jushui River on the basis of tracking investigation, topographic and rock information, and got some preliminary conclusions as listed below： firstly, the large elevation deviation, huge amount of unconsolidated sediments and intensive rainstorm in Jushui River area are beneficial conditions to the generation of huge and destructive debris flows; secondly, The debris flow mainly distributes in the area where shale, fractures exposed, as well as the areas with sharp terrain slope and elevation deviation; thirdly, the debris is characterizedby its group-occurring, high frequency, density and transport capacity. The superposition of the disaster will increase the damage and destroy the road for emergency service.