Recent water-level fluctuations, future trends and their eco-environmental impacts on Lake Qinghai

The water level of Lake Qinghai, the largest lake on the Qinghai-Tibetan Plateau, has increased continuously, at an average speed of 0.21 m per year since 2005, causing a rapid expansion of the lake area. We investigated the hydrological processes of Lake Qinghai and the surrounding watershed that have influenced water level and lake area from 1956 to 2019. Relationships among water level, climate change and human activities were also assessed. Water level and lake area were positively correlated with precipitation and runoff into the lake, and negatively correlated with evaporation. Climate change factors including precipitation and runoff were the primary causes of lake level change, whereas human activities, including variation in a human footprint index, land use, and grassland irrigation, were secondary factors. A time series model forecasted that from 2020 to 2050 water levels will increase further by 2.45 m. Although this increase in water level may have some benefits, such as reduced local desertification, the expansion of lake area will continue to flood low beaches, pasture lands, near shore infrastructure and roads, and impact tourism locations. However, continued water level rise may also have negative ecological effects, such as reduce habitat of seasonal birds and reduced water quality due to erosion and sediment resuspension in shallow nearshore lake areas. Local stakeholders, government authorities, and scientists should give greater attention to anticipated changes in water level, and further ecological studies and infrastructure adaptation measures should be implemented.