【摘要】 甘肃省舟曲县城2010年"8.8"特大泥石流灾害损失惨重,造成1 675人死亡失踪,损毁房屋200余栋,世界震惊。通过现场对舟曲三眼峪泥石流调查和研究,认为"8.8"特大泥石流灾害既是天灾(自然条件),又是人祸(人为因素)。换言之,自然条件和人为因素是导致"8.8"特大泥石流的主要致灾因素。自然因素调查结果表明:1.三眼峪流域在25 km2范围内高差达2 500 m,且大眼峪和小眼峪沟谷纵坡降分别达到33%和36%,地形较为陡峻;2.三眼峪流域内松散固体物质总量约为26.4×106m3,被"8.8"特大泥石流冲出的固体物质仅为1.52×106m3,松散物源丰富;3.小时降雨量为77.3 mm,属极端强降雨。人为因素分析表明:1.城镇建设(建筑物和农田)挤占泥石流排泄通道,导致行洪能力每秒不足300 m3;2.按50 a一遇的防洪标准进行设计,以往防治工程设计标准显然不足。更多还原

【Abstract】 In August 2010 the large debris flows occurred in Sanyanyu valley and Luojiayu valley in Zhouqu county,Gansu province,northwestern China.It was the most destructive and natural disaster during the last several decades.The rare event destroyed more than 200 buildings and flooded about two-thirds of Zhouqu county,killing 1 675 people.The field investigation and research shows that the extra-large scale debris flow disaster is not only a natural hazard but also a man-induced catastrophe.The natural factors for the debris flows have three conditions including steep geomorphology,abundant loose materials and heavy rainfall.Firstly,the altitude difference of the valley is up to about 2 500 m in a catchment area of 25 km2,and the channel gradients of the Dayanyu gully and Xiaoyanyu gully reach 33% and 36% respectively.Secondly,the volume of the deposited loose materials in Sanyanyu valley is estimated to be 26.4 million m3 among which only 1.52 million m3 have been carried by the Zhouqu 2010 debris flows.Thirdly,the hourly rainfall from 11: 00 P.M.of 7 August to 12: 00 P.M.was up to 77.3 mm.Investigation results also show that the iinsufficient design standard of protective measures(e.g.blocking dam and drainage channel) and occupancy problem of buildings and farmland in drainage channel are the main reasons for the heavy losses.The lessons learned from the debris flows will be valuable for the disaster area of Zhouqu County in future disaster mitigation.更多还原