汶川地震引发的山地灾害以及堰塞湖的管理方略

Management of quake lakes and triggered mass movements in Wenchuan earthquake

汶川地震触发了大规模的崩塌与滑坡等山地灾害,形成众多堰塞湖。为分析其风险与应对措施,本文通过野外考察、卫星影像与数据分析等方法,研究了灾后堆积体与堰塞湖的稳定性,以及它们与下切性河流之间的关系。结果显示,山地灾害在不同程度上释放了潜在势能,其中滑坡释放能量最大,因此滑坡堆积体的稳定性较好,而崩塌堆积体稳定性较差。从长期治理角度看,若能控制河床下切则可避免部分灾害的产生。堰塞湖管理方略包括两种:对于风险高的堰塞湖应以拆除为主,而对于风险很小的堰塞湖则应予以保留。震区大部分河流处于不稳定的下切拓宽阶段。保留堰塞湖可以加大河床阻力,使河流提前达到平衡,降低未来地震中山地灾害发生的风险。

The Wenchuan earthquake triggered numerous avalanches and landslides and created many quake lakes. The stability of mass movement deposits and quake lakes and its relationship with riverbed incision are studied by field investigations together with satellite images and data analysis. The mass movements released different degrees of potential energy. The landslides have released the most of its energy and have high stability. The avalanche deposits have lower stability and are dangerous. From the viewpoint of river training, some landslides might be prevented if the riverbed incision were controlled. Two strategies are applied to manage the quake lakes: to remove the high risk lakes and to preserve the low risk lakes. Most rivers in the earthquake-hit area are in unstable geomorphology stage. Lakes preservation may change the rivers into equilibrium, thus, reduce the mass movements in a future earthquake event.