The Spatiotemporal Change of Xiao Qaidam Lake from 1990 to 2020 and Its Potential Hazards

Abstract

In the climatic context of warming and humidification in Northwest China, most lakes in Qinghai Province experienced a rising water level and expanding area, inundating grassland and infrastructure around lakes, and even extreme events such as lake outburst floods. Based on Landsat TM/ETM+/OLI and GF PMS images, lake water level data, SRTM digital elevation model (DEM), GlobeLand30 and meteorological data used in this study, we analyzed the area change of Xiao Qaidam Lake in Qaidam Basin with its causes, factors and potential hazards. The results show that the area of Xiao Qaidam Lake increased by 60.42 km2 (85.43%) from 1990 to 2020, which can be roughly divided into three stages: fluctuation decline in 1990–2001 (−1.89 km2/a); relatively stable in 2002–2014; and rapid expansion in 2015–2020 (8.54 km2/a). In 2020, the water level and water volume of Xiao Qaidam Lake increased by 3.62 m and 0.39 km3, respectively, compared with 2015, resulting in the inundation of an area of 54.55 km2 of grassland around the lake and a direct threat to the Liuge and Dexiao Expressways. Both the increase in annual precipitation (12.63 mm/10a) and the decrease in potential evapotranspiration (−13.38 mm/10a) since 1990 are the main reasons for the rapid expansion of Xiao Qaidam Lake, and the increasing trend of climate warming and humidification will lead to the continuous expansion of Xiao Qaidam Lake in the next decades. According to the water volume growth rate from 2015 to 2020, it is predicted that by 2024 the area and water level of Xiao Qaidam Lake will reach 154 km2 and 3180 m, respectively, and part of Liuge and Dexiao Expressways will be submerged. Therefore, it is urgent to strengthen the monitoring of Xiao Qaidam Lake and formulate corresponding disaster prevention and reduction measures.