大规模沟谷型泥石流成因与减灾启示——以黑水县谷汝沟“7·14”泥石流为例

Causes of large-scale gully debris flow and enlightenment of disaster reduction——Taking the“7·14”debris flow in Guru Glluy of Hishui Ceounty as an example

沟谷型泥石流具有谷坡陡峻、相对高差大、沟道坡度大等特点,往往形成大规模的泥石流灾害。2021年7月14日20时许,黑水县谷汝沟发生大规模泥石流灾害,造成直接经济损失3300万元。为提高和完善泥石流灾害的预测预警手段与减灾水平,以沟谷型泥石流谷汝沟“7·14”泥石流为典型研究对象,通过现场勘察、模型计算、流域地貌信息熵和气象分析等方法,揭示谷汝沟“7·14”泥石流特征,分析其成因,预测其未来发展趋势。结果表明:谷汝沟“7·14”泥石流容重为1.83g/cm3,属于黏性石流,平均流速为11.2m/s,泥石流峰值流量达到991.2 m3/s;流域处于壮年偏幼期的地貌发育阶段,为谷汝沟“7·14”泥石流暴发提供了充足的动力势能条件,49.7mm的日降雨量是泥石流的激发因素;根据灰色灾变预测模型,谷汝沟将在2027年、2034年、2042年暴发泥石流灾害。研究成果有助于完善沟谷型泥石流的预测预警,可为其他地区泥石流防灾减灾提供参考。

Gully debris flow has the characteristics of steep valley slope,large relative height difference and large gully slope,which often forms large-scale debris flow disasters.At about 20:00 pm on July 14,2021,a large-scale debris flow disaster occurred in Guru Gully of Heishui County,causing a direct economic loss of 33 million yuan.To improve and perfect the prediction and early warning means and disaster reduction level of debris flow disaster,the“7·14”debris flow in Guru Gully was taken as the research object.Through field investigation,model calculation,watershed geomorphic information entropy and meteorological analysis,the characteristics of the“7·14”debris flow in Guru Gully were revealed,its causes were analyzed,and its future development trend was predicted.The results show that the bulk density of the“7·14”debris flow in Guru Gully is 1.83 g/cm~3,which is a viscous debris flow,the average velocity of 11.2 m/s,and the peak of debris flow reaches 991.2 m~3/s.The mature and juvenile landform development stage provides sufficient dynamic potential energy conditions for the“7·14”debris flow in Guru Gully outbreak.The daily rainfall of 49.7 mm is the triggering factor for the debris flow.According to the gray catastrophe prediction model,the Guru Gully will have an outbreak of debris flow disasters in 2027,2034,and 2042.The research results help to improve the prediction and early warning of gully debris flow,and can provide reference for debris flow prevention and mitigation in other areas.