Characteristics of the Spatial Distribution of Large Active Landslides in a Potential Cascade Reservoir Area Along the Upper Jinsha River

The upper Jinsha River is not only a geologically complex and landslide-prone area but also a cascade hydropower stations corridor in China. It is paramount to understand the spatial distribution characteristics of the landslides, especially active ones, for future geological hazard prevention and mitigation in a cascade reservoir area. An integrated observation and interpretation technique was carried out to document the landslides along the upper Jinsha River. 217 active landslides were identified after a combination of field investigation and interpretation. Multi-source data, including geologic data, earthquake data, and digital elevation model, were used to reveal the spatial patterns of these landslides. The correlations between the active landslides and factors. i.e., slope, aspect, elevation, lithology, and distance to fault were analyzed. It could be concluded that the distance to the Jinsha River, the distance to the fault, and the lithology are the most important factors for the distribution of active landslides. There is no apparent relation between historical earthquakes and active landslides. Active landslides are most abundant where faults are concentrated, soft and weak rocks crop out, and areas are eroded by the river. After the impoundment of the cascade reservoir, about a third of active landslides will partly dip into reservoir water with a low submergence ratio.