Unraveling the mechanisms underlying lake expansion from 2001 to 2020 and its impact on the ecological environment in a typical alpine basin on the Tibetan Plateau

Abstract

Yanhu is a typical alpine lake on the northeastern Tibetan Plateau. Its continuous expansion in recent years poses serious threats to downstream mega infrastructure. As a result, studies of the mechanisms underlying lake expansion are urgently needed. We used the elasticity method within the Budyko framework to calculate the water balances in the Yanhu basin and the neighboring Tuotuo River basin. Results show intensification of hydrological cycles and positive trends in the lake area, river runoff, precipitation, and potential evapotranspiration. Lake expansion was significant between 2001 and 2020 and accelerated between 2015 and 2020. Precipitation increase was the key factor underlying the hydrological changes, followed by glacier meltwater and groundwater. The overflow of Yanhu was inevitable because it was connected to three other lakes and the water balance of all four lakes was positive. The high salty lake water diverted downstream will greatly impact the water quality of the source area of the Yangtze River and the stability of the permafrost base of the traffic corridor.