龙门山地区震后泥石流灾害区域预警研究

512汶川地震造成大量松散堆积物，导致震后触发泥石流的极端降雨量比震前显著降低。在龙门山地区震后泥石流发育特征分析的基础上，探讨了震后触发泥石流灾害的区域降雨阈值及其地域差异性，震后触发泥石流的72小时雨量分布特征为:映秀汶川一带为75~100mm，茂县北川一带以100~160mm为主，上述区域外围及平武青川一带为160~200mm；在龙门山前的雁门茶坝、龙门山后山的禹里平武之间为200mm以上。综合考虑地震地质、地形地貌和降雨等因素，建立了地震扰动区泥石流预警指标体系。采用加权信息量模型完成了龙门山区泥石流易发性评价，然后采用年最大72小时降雨量为主要触发因素，开展了震后5年的泥石流危险性预测评价及区域预警研究，提出泥石流的区域危险性是动态变化的，高危险区主要随降雨量和松散堆积物空间分布而变化，为震后泥石流灾害气象预警和防范等提供了依据。 

Regional Warning of Debris Flow Hazards after Wenchuan Earthquake in Longmenshan Region

Massive loose deposits caused by the Wenchuan earthquake on May 12, 2008 have resulted in significant decrease of rainfall threshold of post-earthquake triggering debris flow in comparison with pre-earthquake level. Based on the post-earthquake debris flow characteristics analysis in the Longmenshan region, the regional rainfall threshold of triggering debris flow and its regional differences were discussed. The 72-hour rainfall distribution characteristics of post-earthquake triggering debris flows are as follows: 75-100 mm in YingxiuWenchuan area, 100-160 mm in MaoxianBeichuan area, 160-200 mm in around above regions and PingwuQingchuan area, and 200 mm or more in YanmenChaba area and YuliPingwu area. Based on comprehensive analysis of seismogeology, topographic and geomorphic conditions, extreme rainfall and regional characteristics of post-earthquake debris flows, the regional rainfall threshold of triggering debris flow, as well as the warning index system, for earthquake-stroked region was established. The weighted information model was adopted to complete debris flow susceptibility assessment in the earthquake-stroked Longmenshan region. Then, taking the annual maximum 72-hour rainfall as a main trigger factor, the debris flow hazard assessment and regional warning study in 5 years after the Wenchuan earthquake were conducted. The results show that the regional debris flow hazard is dynamic, and the areas with high debris flow hazard change with the spatial distribution of rainfall and loose deposits.