甘肃岷县两次强降水致山洪泥石流灾害特征对比分析

Cause of two heavy rainfall causing massive mudslide in Minxian County,Gansu Province

从致灾因子、灾害风险的角度对甘肃岷县2012年5月10日和2016年6月23日发生的两次强降水过程进行了特征对比分析。结果表明:在有利的大尺度环流背景下,明显的中尺度特征导致强对流天气发生是造成岷县特大山洪泥石流等地质灾害发生的主要气象触发因素;前期降水、短时强降水强度及落区在岷县特大山洪泥石流的形成中起到了决定作用,而强降水伴随特强冰雹、阵性大风对岷县特大山洪泥石流的形成则起到了进一步的推动作用。

In order to provide scientific basis for government decision making and disaster risk assessment, we analyzed the characteristics of two mountain flood disasters caused by heavy rainfall in Minxian County, Gansu Province, China on the 10^th of May 2012 and the 23^rd of June 2016 respectively. The results showed that the obvious mesoscale features under the favorable large-scale circulation backgrotmd led to the occurrence of strong convective weather, which is the main meteorological trigger for the mountain floods. The antecedent precipitation, strong precipitation intensity in short time period and the rainfall area play a decisive role in the formation of this massive mountain flood in Minxian County. There had been more precipitation before the 10th of May 2012, and the soil had a high water content. All this made Minxian on the verge of a geological disaster. The torrential rain formed the remarkable surface runoff directly and triggered the massive mudslide. The last push was the strong hail combined with the strong gust wind that increased the dragging force and washed away the surface badly.