资源环境科技发展态势分析平台

Variability of water balance in closed lakes in the Tibetan Plateau (TP) can be a useful indicator of climate change. While most of lakes over the TP have been expanding, especially in the inner TP, the Yamzho Yumco in the Southern TP faced a significant water level decline in 1975-2012. This study focused on attribution of the water level changes to various factors with the help of a physically based and a statistical model for the water balance of the lake, along with observed precipitation and lake surface evaporation data. Results showed that climatic conditions dominated the changes in water level until 1997, and human activity through the construction and operation of a hydropower station started to play a strong role after 1998. The lake level has gone up and down due to changes in precipitation-generated recharge and evaporation over the study period. The water level decline in 1975-1997 was mainly due to low level of the recharge from precipitation and land runoff. However, the drastic decline of water level in 2006-2012 was far from the reach of the climatic conditions. It was indeed caused by the intensified influence of the building and operation of a nearby hydropower station. It was also found that the water level change during the whole period (1975-2012) followed the aridity index for the basin, especially before 1989. This provides an effective way to predict future changes of lake level, if reliable projections for future climate change and human activity are available.