Landscape Disturbance Effects of the Large-scale Water Storage Activity in the Baihetan Reservoir on the Jinsha River, China

Abstract

Constructing large hydroelectric power stations in canyon areas is widely accepted as a solution to meet energy demands. However, large-scale water storage elevates water levels, shifts the water-land boundary, increases evaporation, and alters the microclimate, potentially triggering a chain of environmental responses. This raises concerns about whether such changes could increase abnormal precipitation events, thereby stimulating more widespread slope failures and vegetation changes, ultimately disturbing the landscape. The Baihetan Hydropower Station, located on the lower Jinsha River in China, serves as a case study for exploring these effects. By monitoring long-term surface deformations, abnormal precipitation, topography, geomorphological parameters, and vegetation changes, we have gained insights into the macro disturbances caused by water level fluctuations. Since the reservoir began storing water, slope failures have markedly increased, particularly in the form of creeping slopes and bank collapses in the drawdown zone. This period has also seen a reduction in total precipitation, an increase in abnormal precipitation, and slower vegetation growth. Further analysis reveals that while rising water levels primarily destabilize reservoir shore slope-failures, precipitation also significantly influences this instability. The greatest threat to shore stability arises when water levels drop and are followed by heavy rainfall. Although the severity of abnormal precipitation has increased post-impoundment, it has not led to more extreme precipitation events. Vegetation growth on active slopes near the reservoir is mainly controlled by changes in precipitation, with vegetation decline due to slope instability being limited and not widespread. These findings contradict initial assumptions, indicating that landscape disturbances due to water storage are limited and have not led to severe, uncontrollable chain reactions.