泥石流堰塞湖影响区域评估及其应急预案) 以汶川县磨子沟为例

2008 年汶川/ 5 # 120地震后, 汶川震区内大量新、老泥石流沟的泥石流活动频度增加, 致使泥石流堰塞湖的形成几率也随之增大。通常泥石流所形成的堰塞体稳定性较差, 从形成至溃决通常在几小时内发生, 人工工程干预的可能性小。因此, 做好堰塞湖溃决洪水影响区域评估和溃决洪水应急预案, 成为必要且有效的减灾手段之一。但泥石流堰塞湖的溃决洪水既不同于一般意义的洪水, 也不同于人工大坝的溃决, 是过去应急预案研究中较少涉及的灾种。选择汶川磨子沟作为研究对象, 在泥石流堰塞湖溃决危险性评估基础上提出溃决洪水应急预案的编制原则和方法: 首先确定泥石流堰塞湖可能溃决的最大洪峰流量、淹没高度、泛滥范围和持续时间; 其后, 实地调查居民点, 圈定洪水淹没范围和危险区人口数, 并根据地形条件制定可能的撤退路线; 最后, 结合政府部门的行政安排, 制定险情通报程序、险情发生安全保障措施和预案启动、结束的时间节点。试图为其余泥石流堰塞湖溃决洪水危害应急预案制定提供借鉴, 提升应对突发泥石流堰塞湖溃决事件的效率。

Assessment of influence area and emergency plan for debris2flow dammed lake- A case study in Mozi Gully of Wenchuan, Sichuan

After the "5. 12 Wenchuan ear thquake" , a lar ge number of new and old debr is2flow g ullies increase their activities, andthe possibility of dammed lake fo rmed by debris flow increases as w ell. The dam formed by debris flow is unstable, and ther eare only a few hours f rom the dam fo rmatio n to outbur st, so it is diff icult to conduct man2made eng ineer ing interv ention. Assess2ment of influence a rea and establishment of emergency plan for debr is2flow dammed lake are necessar y and effective for disasterreductio n. The dam2failure flood caused by debris2flow dammed lake is differ ent from the tr adit ional flood or the outburst ofman2made dam, which is an infrequent disaster ty pe in the emerg ency plans. The Mozi Gully was cho sen as the study object, andthe pr inciples and preparatio n metho ds of emerg ency plans wer e put fo rw ard on the basis of r isk assessment fo r the outburst ofdebris2flow dammed lake. Fir st, the po tent ial peak f low , flo od heig ht, and outbur st dur atio n time w ere determined fo r the out2burst of debris2flow dammed lake. Second, the inundat ion area w as circled and r isk po pulation was estimated throug h f ield sur2v ey, and po ssible escape r oute and after car e locations w ere cho sen acco rding to ter rain co ndit ions. Finally, t he notificat ion pr oce2dures, secur ity measures, and time node o f emerg ency plan star ting and ending w ere set based on go vernment al administr ativ earr ang ements. T he emerg ency plan fo r the Mo zi Gully can lay the foundatio n for t he similar plans of other dang erous debr is2flowgullies and impr ove the response efficiency of debr is2flow dammed lake.