喜德县中坝村火后泥石流发育特征及预警避险

Study on the development characteristics of post-fire debris flow and its early warning risk aversion in Zhongba Village,Xide County

2020年5月7日四川省凉山彝族自治州喜德县鲁基乡中坝村发生森林火灾,过火面积约6.7 km^(2)。林火后火烧迹地坡面灰烬厚约2~6 cm,同时表层土壤结构被扰动,在6月4日傍晚20 min左右的强降雨下,中坝村后山4条沟道同时暴发了火后泥石流灾害,对沟口的41户164名居民构成严重威胁。通过遥感解译、野外调查,查明了火烧区4条沟道的火烈度及物源分布特征,分析了火后泥石流的发育特征,并进行了危险度评估。基于火后泥石流暴发降雨阈值、实时雨量监测数据与群测群防于一体,提出了一套适用于山区火后泥石流的预警避险方案,在该沟得到成功应用,并确保了沟口居民安全。

On May 7,2020,a forest fire broke out in Zhongba Village,Luji Township,Xide County,Liangshan Yi Autonomous Prefecture,Sichuan Province,covering an area of about 6.7 km2.After the forest fire,the ash on the slope was about 2~6 cm thick,and the surface soil structure was disturbed.Under the heavy rainfall of about 20 min in the evening of June 4,the postfire debris flow disaster broke out in the four gullies at the back mountain of Zhongba Village,which is a great threat to the 164 residents of 41 households in the gully mouth.Through remote sensing interpretation and field investigation,the fire intensity and deposit distribution characteristics of four gullies in the burned area are identified,the development characteristics of postfire debris flow in Zhongba Village,Xide County are analyzed,and the risk assessment is carried out.Based on the real-time rainfall data obtained from group survey and group prevention,a set of early-warning and risk avoidance scheme for debris flow in mountain areas after fire is proposed,which has been verified by this example.