Influencing mechanism and hydrogeological implications of water level fluctuation of lakes in the northern Qaidam Basin, Qinghai-Tibet Plateau

The Qaidam Basin (QB) is a concentrated distribution area and chemical industrial bases of salt lakes in China. Lakes in the QB have been expanding during the past 20 years. Rapid lake expansion resulted in some considerable scientific issues on the protection of salt lake resources and infrastructure, and monitoring of hydrological processes at the lake-basin scale. Although the spatial-temporal trends of lake changes on the Qinghai-Tibet Plateau (QTP) have been well documented, the underlying influencing mechanism and hydrogeological implications of rapid lake changes in the QB are not well understood. Three lakes in the northern QB were selected to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations. The influencing mechanism and hydrogeological implications of rapid changes of terminal lakes were discussed in combination with the reported increasing precipitation rate and mass balance of glaciers in the northern QTP. Results reveal the following: (1) the fluctuation pattern of Sugan Lake was asynchronous and out of phase with that of Xiao Qaidam and Toson Lakes during the monitoring period; (2) Sugan Lake water rose gradually, and the rise interval was from late April to early July. In contrast, Xiao Qaidam and Toson Lakes took on a rapid and steep rise, and the rise intervalwas from late July to September; (3) the influencing mechanisms for rapid lake fluctuations are controlled by different factors: glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson Lakes; (4) in accordance with different intervals and influencing mechanisms of rapid lake expansions in the QB, hydrological risk precaution of lakes and corresponding river catchments was conducted in different parts of the basin. This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution, and protection of salt lake resources along with rapid lake expansions in the arid area.