Exploring The Potential Factors On The Striking Water Level Variation Of The Two Largest Semi-Arid-Region Lakes In Northeastern Asia

Global warming and drying have caused desiccation of lakes in arid and semi-arid regions worldwide, and the mechanisms underlying sharp decreases in water level of great lakes in arid and semi-arid regions in recent decades require elucidation. Using a combination of multiple statistical and modeling methods, we extracted multi-decadal trends from water level time series (similar to 1960-2017) of the two largest lakes in northern China, and explored the influences of hydro-meteorological factors on the multi-decadal and inter-annual variation in lake water level. The hydrology components of the Hulun Lake basin varied with greater amplitude than those of the Qinghai Lake basin, with water level decreases of 5.3 (1991-2011) and 3.1 (1961-2004) m in Hulun Lake and Qinghai Lake, respectively. River runoff influenced multi-decadal changes in water level of the two great lakes most, followed by lake surface evaporation and precipitation at the lake surface. Lake surface evaporation, driven by potential evaporation and lake area dynamics, was the largest hydrology component of the two great lakes. Lake surface evaporation mitigated the decline of Hulun Lake over 1995-2011, while it aggravated the decline of Qinghai Lake over 1990-2005. Although El Nino-Southern Oscillation significantly affected various hydrometeorological factors, it contributed less than 6% of inter-annual variation in Hulun Lake, and no significant effect on the variation in Qinghai Lake was found. Pan evaporation was negatively correlated with precipitation and land evapotranspiration in both great lake basins.