金沙江下游位于青藏高原、云贵高原向四川盆地过渡的横断山区，地形起伏大，构造变动强烈。遥感调查确定有体积大于100×106m3的滑坡400个，这些滑坡大多分布在金沙江下游的中段及支流沿岸400m～3200m地带。滑波活动方式复杂多样，以高速、剧冲式和碎屑流滑坡对工程和环境影响最大。目前，约有70%的滑坡处于局部活动状态。调查区内，有流域面积大于0.2km2、堆积扇面积大于0.01km2的一级支流沟谷型泥石流438条，主要分布在调查区中段。其中粘性泥石流299条，占总数的68%,稀性泥石流仅占总数的11%.本区泥石流处于活跃期，新泥石流还在大量发展。本区滑坡、泥石流灾害严重，对环境有巨大影响。
The lower reach of the Jinsha River, the study area of this paper, lie in the Hengduan Mountains in the transitional zone between the Qinghai Tibetan Plateau and the Yuannan Guizhou Plateau. Stretching for 786 km from Panzhihua to Yibin, the topography of the area rises and falls sharply. The area’s geology is complex and tectonic movements new and active. The area has rich water resources. The Ministry of Electric Power has planned 4 large scale hydroelectric stations with an installed capacity of 36.9 million kW. The area has experienced repeated landslides and rock mud debris flows that have seriously affected its engineering work and economic development. Remote sensing interpretation and site verification reveal that the area has 400 landslides with volumes >10 8 m3. These landslides are distributed mainly along the middle section of channel bank and in the river’s tributaries where the elevations range between 400 m～ 3 200 m. The forms of the landslides are various and complex. Those with high rushing speeds and large scale clastics are the most damaging to engineering work and the environment. At present, about 70% of the landslides are partially active. The study area’s drainage basin is >0.2 km2 in size. In the first grade tributaries of the river, there are 438 large scale debris flows whose deposit fans are 0.01 km2～3.1 km2. These debris flows are distributed mainly in the study area’s middle section where the elevation is 500 m～4 000 m. The areal size of 80% of the debris flows’ drainage basins is 1 km2～50 km2. The study area has 299 viscid debris flows, accounting for 68% of the total, with only 11% of the total being dilutive. The numbers of gullies where debris flows of extra large, medium and small scales may occur are, respectively, 6, 136, 183 and 103. Numerous new debris flows are being developed in the area. Landslides and debris flows have caused serious damages to the area and strongly impacted the environment. The massive volume of silt the river carries from the area posses a major problem to the Three Gorges Dam downstream.
