5·12汶川地震对磨子沟的影响及震后泥石流活动状况

磨子沟位于四川省汶川县银杏乡,属岷江上游右岸支流,5· 12汶川地震对其造成了严重影响.地震引发了大量的崩塌、滑坡,其中8处大型崩塌和滑坡对沟道造成了严重堵塞,并为泥石流活动提供了良好的条件.地震后磨子沟泥石流十分活跃,仅2008年7-9月就暴发了75阵阵流,3次堵断岷江并形成堰塞湖,淹没了岷江左岸村 庄;2009-2011年又多次暴发泥石流并堵塞岷江.持续的降雨监测数据表明,震后初期磨子沟发生泥石流的日雨量条件急剧降低,目前有逐步回升的趋势.通过对比磨子沟流域震前(2005年6月)、震后(2008年6月)及泥石流事件后(2010年12月)等不同时段的遥感影像,结合实地调查和震后高分辨率航空影

Debris Flow Activity of Mozi Gully after Wenchuan Earthquake on May 12

The Mozi gully,located in Yinxing,Wenchuan County of Sichuan province,is a tributary of Minjiang River at the right bank.This gully was seriously affected by the Wenchuan earthquake on May 12,2008.Numerous collapses and landslides triggered by the earthquake provided abundant materials for debris flow,and eight of them blocked Mozi gully.Debris flows had occurred many times in this gully from July to September in 2008 and 2010,and blocked the Minjiang River for 3 times and inundated villages on the left bank.Similar situations happened in 2009,2010 and 2011.According to field investigation and interpretation of remote sensing images and aerial images in different periods,there are more than 3 000×104 m3 solid loose materials in Mozi gully after the earthquake.According to debris flows in different rainstorm frequencies,the biggest debris flow on July 14,2008 is calculated to be 257 000 m3,with a peak discharge of 541 m3/s,once in half a century.The sediment volume carried out from the gully is only 2.5×106 m3,and the left materials are still of high risk of triggering debris flows and blocking the Minjiang River.