四川省九龙县娃娃沟泥石流运动特征与堵河成灾机制分析

Debris flow activity characteristics and blocking up river mechanism in Wawa Valley,Jiulong County,Sichuan Province

2006年7月16日娃娃沟流域暴发的大规模泥石流,给下游3个电站造成巨大经济损失,是大渡河流域一次典型的灾害性泥石流。分析得出,娃娃沟泥石流重度高、搬运能力强,泥石流固体物质砂、石混杂,粗大砾石含量高;暴发频率低、规模大,流速及峰值流量分别高达10.78m/s及798.5m3/s;在汇口处,泥石流堆积物堵塞河道是引起下游电站受灾的重要原因,高重度、粗颗粒、大流量的组合是此次泥石流堵江的重要原因。堵河判别计算结果显示在发生百年一遇泥石流时,该断面均有发生堵河的可能。娃娃沟泥石流表明:①在大渡河支流的泥石流沟周边的中小电站极有可能在泥石流暴发时受到破坏。因此,电站建设过程中应加强对周边泥石流沟的防灾减灾工作;②虽然娃娃沟流域植被良好,但仍然发生了大规模泥石流。表明植被不能完全避免泥石流的发生,对于此类泥石流沟不能疏忽大意。

On July 16, 2006, a large debris flow happened in Wawa Valley, carried out tremendous economical lost. This is a typical debris flow calamity event occurred in Dadu river catchment. Based on analyzing, it revealed that debris flow in Wawa Valley had low occurrence frequency, while its magnitude was big and concentration was high. Meanwhile, calculation results shown velocity and peak discharge of this debris flow were up to 10.78m/s and 798.5m^3/s respectively. And debris flow deposition blocked up main river in the mouth of Wawa Valley. Combination of high concentration, large rocks and big discharge of this debris flow wasmain reason induced the deposition jammed river. On the one hand, the debris flow of Wawa Valley shown that hydro power stations which were in the adjacent areas would be mangled by debris flows. Therefore, the control and management of these debris flows should be enhancement. On the other hand, serious debris flow calamity occurred in well-vegetated Wawa Valley, it displayed flourishing vegetation couldn＇t avoid debris flow occurrence completely.