汶川地震区暴雨滑坡泥石流活动趋势预测

Activity Tendency Prediction of Rainfall Induced Landslides and Debris Flows in the Wenchuan Earthquake Areas

汶川大地震发生后,暴雨又激发了新的滑坡和泥石流发生。为探讨汶川地震区暴雨滑坡泥石流活动趋势,对比分析了日本关东大地震和台湾集集大地震后诱发滑坡和泥石流活动趋势,在此基础上,对汶川地震区未来滑坡、泥石流活动趋势作了预测分析。同时,还讨论了估算不同强度降雨条件下滑坡面积和泥石流冲出量的方法。初步研究表明,汶川强震区至少在近10a内,滑坡和泥石流活动趋势是强烈的,之后地质条件将逐渐趋于稳定。本研究选择了面积为5.9km2的北川县城西侧斜坡为研究区,计算结果是如果一旦遭遇100a一遇降雨,新增滑坡面积可达166.97×104m2,约占整个研究区流域面积的28.3%。本研究还预测了魏家沟、苏家沟流域的不同频率降雨条件下的泥石流土砂产量,在100a一遇降雨条件下,泥石流土砂产量分别达71.0×104m3和49.2×104m3。研究成果为进一步认识汶川地震区后续降雨作用诱发的滑坡泥石流活动趋势提供参考。

After Wenchuan earthquake,the subsequent rainstorms caused new landslides and debris flow occurrence. To explore the future activity of rainfall induced landslides in the Wenchuan earthquake areas,comparative analysis of the earthquake-induced landslides and debris flow activity trends of the Wenchuan earthquake with the Great Kanto earthquake in Japan and the Chi-Chi earthquake in Taiwan was made,on this basis,the future development of landslides in the Wenchuan earthquake areas was analyzed and predicted. The preliminary study results indicate the Landslide and debris flow activity in the Wenchuan erathquake areas will keep still intense in future 10 years. After that,the geological condition will be gradually stable in the future. A study area of 5.9 km2 was selected in western slope of the Beichuan city. The new landslide area induced by heavy rainfall with 100-year return period will be approximately 166.97×104 m2 ,taking up 28.3% of total study wtershed area. This study also predicted the outflow volume of debris flows with different return period in the future. The result shows the outflow volume of debris flow in the watershed of Weijia gully and Sujia gally were estimated to be 71.0×104 m3 and 49.2 ×104 m3 respectively. This research work can provide a reference for further understanding the role of Wenchuan earthquake follow-up rain-induced landslide and debris flow activity trends.