The Influence of Reservoirs on Landslide Erosion

The evolution of the landslide erosion of bank slopes in reservoir regions is crucial for disaster prevention and mitigation in hydropower projects, and it is also an important topic to investigate the impact of anthropogenic activities on the environment. A dispute exists on the landslide erosion of bank slopes under reservoir impoundment. In this paper, we chose the Xiluodu reservoir as a typical case for analysis. The reservoir is located on the eastern Qinghai–Tibetan Plateau and ranks as the fourth largest hydropower station in the world. Firstly, we identified landslides using the multi-temporal image interpretation method before and after impoundment in the reservoir area, and established a landslide dataset. On this basis, we analyzed the spatiotemporal distribution of these landslides, and derived the landslide erosion rate based on the quantitative relation between landslide volume and area. The results showed that the landslide erosion rate increased sharply during the initial impoundment period and decreased exponentially. We then analyzed reservoir-induced landslides worldwide and found that most reservoir bank slopes tend to stabilize after about five years of impoundment, eventually even becoming more stable than pre-impoundment, regardless of the location, scale, water fluctuations, and geoenvironment. Thus, in the long term, reservoir construction tends to reduce erosion and contribute to bank stability. This study provides a preliminary answer to the controversial issue of the impact of reservoir construction on the natural environment.