桂林“5.9”山体滑坡的暴雨成因分析

Analysis on the Heavy Rain Causes of the Landslide on May 5^(th) in Guilin City

对造成2011年5月9日广西桂林咸水乡山体滑坡的暴雨成因进行了分析,结果表明,滑坡是由于暴雨因素诱发的地质灾害,短时强暴雨是造成山体滑坡的直接原因。大量的水汽传送到滑坡点,同时低层辐合抬升,因而滑坡点是大暴雨的发生地。滑坡发生滞后强降雨结束2.5 h。滑坡点位于暴雨中心带,暴雨区位于高空急流的右侧,200h Pa为强烈辐散区,高空辐散带的走向与山脉走向一致。西南低空急流与地形的相互作用是暴雨形成的直接原因,雷达回波显示在"湘桂走廊"存在强风速的出流与横向风速梯度,对应反射率有弓状回波,同时具有前侧V形入流缺口和后侧V形下沉缺口等对流单体特征。

The heavy rain causes which led to the landslide in Xianshui town of Guilin city on May 5th, 2011 are analyzed. It is shown that the landslide geological disaster is resulted from heavy rain and the short-term torren- tial rain is the direct cause to the landslide. A lot of water vapor is transferred to the landslide point, and at the same time the low level convergence led to the strong uplift, therefore the heavy rain occurred on the landslide point. And the occurring of landslide lagged 2. 5 hours behind the ending of the severe torrential rain. The land- slide point located in the center area of the heavy rain region, which is on the right side of the high level jet stream, and the strong divergence area is at 200 hPa. The upper divergence region is corresponded with the mountains re- gion. The interaction between the southwest low level jet and topography is the direct cause of torrential rain. Radar echo showed that in the I-Iunan Guangxi Corridor there are strong outflow and transverse wind speed gradient, with refectory convective cell characters such as FFN at the ahead of bone echo and RIN at the behind of the bone echo.