“8·3”鲁甸地震背景下甘沟流域泥石流危险性评价

RISK ASSESSMENT OF DEBRIS FLOW IN GAN GOU RIVER BASIN UNDER THE BACKGROUND OF“8·3”LUDIAN EARTHQUAKE

2014年8月云南省鲁甸县发生6.5级地震,位于震源中心地带的甘沟流域受地震影响,诱发大量次生地质灾害,流域内松散堆积物质增加,泥石流灾害的潜在危险增大,对沟口集镇造成威胁。本文基于对甘沟流域野外实地调查,综合考虑降雨对震后泥石流的影响,选取泥石流规模、流域面积、日最大降雨量、主沟长度、相对高差、流域切割密度、不稳定沟床比等7个评价因子,通过调整分辨系数为0.2272的灰色关联法确定其客观权重,并在此基础上采用多因素综合评价方法计算泥石流危险度,对其进行危险性定量评价。结果表明,震后甘沟流域泥石流危险性属中度危险,诱发中等规模泥石流的可能性较大。

On August 3,2014,an earthquake occurred in Ludian,Yunnan Province.The Gangou River Basin in the center of the earthquake was affected by the earthquake,which induced a large number of secondary geological disasters.The increase of loose accumulated materials and the potential danger of debris flow disasters posed a threat to the towns in the river mouth.Based on the field investigation of the Gangou watershed,considering comprehensively the impact of rainfall on debris flow after the earthquake,this paper selected seven evaluation factors,such as debris flow scale,drainage area,maximum daily rainfall,main channel length,drainage area relative relief,drainage area cutting density and shifting bed proportion to determine the objective weights through the adjustment of the gray correlation method with the resolution coefficient of 0.2272,on the basis of which,the multi-factor comprehensive evalution method was used to calculate the risk of debris flow and its risk quantitative evaluation.The results showed that the risk of devris flow in Gangou river basin was moderate and the possibility of inducing medium-scale debris flow was greater.