河南栾川“7·24”泥石流特征及成因

Characteristics and Causes of the 24 July 2012 Debris Flow in Luanchuan County of Henan,China

2010-07-24,河南省栾川县境内普降暴雨,引发多处泥石流灾害(简称"7·24"泥石流),造成重大人员伤亡和财产损失。对泥石流的分布、类型、静动力学特征、灾害和损失进行总结,在此基础上,从降雨、地形和物源条件对泥石流成因进行了分析。结果表明:"7·24"泥石流分布范围主要沿着雨量高值区、地貌过渡区、人类活动区展布,泥石流类型多样,危害严重。丰富的前期降雨量,极高的日降雨量和短历时高雨强是泥石流的激发因素,充足的前期降雨量可以极大削弱物源地岩土体的强度。大部分泥石流沟的山坡坡度和沟床比降属于泥石流易发范围,说明栾川县的地形条件有利于泥石流的形成。区内泥石流物质来源丰富,通过"表观物源量"指标对物源进行分区发现,物源主要集中在区域性断裂和人类活动区附近。"7·24"泥石流是有利的地形、充足的物源和高强度的降雨共同作用的结果。

On July 24,2010,due to a widespread rainstorm,most of the county was attacked by catastrophic debris flow,causing heavy human casualties and property damages. The distribution,type,static and dynamic characteristics,disaster and loss of 7. 24 debris flows in Luanchuan County are summarized. On this basis,the causes of 7. 24 debris flows are analyzed in three aspects of rainfall condition,topographic condition and source condition.The analysis results show that 7. 24 debris flows mainly distributes in high rainfall area,landscape transition area and human activity area. 7. 24 debris flows have various types and caused serious damages. The abundant prophase rainfall,high rainfall and short duration rainfall intensity provides favorable rainfall conditions. The abundant prophase rainfall can greatly weaken the strength of rock soil mass. The slope gradient and gully bed gradient of most debris flow gullies belong to the scope of prone range. The topography conditions of Luanchuan county is favorable for the formation of debris flow. The material sources for debris flows are rich in Luanchuan county. A new indictor＂apparent source＂is used to zone the area. The result indicates that the material sources are mainly concentrated in the regional fracture and human activity area. In a word,the 7. 24 rainstorm-induced debris flow disaster was the product of the combined action of favorable topography,material source conditions and high-intensity rainstorm.