Estimation of lakes water storage and their changes on the northwestern Tibetan Plateau based on bathymetric and Landsat data and driving force analyses

Lake water storage changes in four lakes were analyzed based on in situ bathymetric survey data and Landsat images in the extremely dry and cold northwestern Tibetan Plateau region. The results indicated that Bangdag Co and Aksai Chin Lake, which are glacier-fed and closed lakes, showed decreasing trends from 1976 to 1996, then increasing trend from 1996 to 2015, during which period water storage increased by 1.24 km3 and 1.37 km3, respectively, and 65% of the water storage increase in Aksai Chin Lake during this period occurring in 2006 and 2013. Longmu Co, which is a non-glacier-fed lake, exhibited little variation from 1976 to 1996 and a slight increase of 0.1 km3 from 1996 to 2015. The precipitation, temperature and potential evaporation (Ep) trends indicated that lake shrinkage from 1976 to 1996 was attributed to less precipitation and less meltwater at lower surface air temperatures. Decreased Ep (15.5 mm/y) contributed approximately 2% and 4% to the lake expansion of Aksai Chin Lake and Bangdag Co from 2000 to 2009. Based on the assumption of equal precipitation-evaporation for the study area, glacial meltwater contributed 76.6% to the lake expansion of Bangdag Co from 2000 to 2015. Because change in lakes' water storage showed a large difference between glacier-fed lakes and non-glacier-fed lakes from 1996 to 2015 under relatively high precipitation conditions, it is suggested that glacial meltwater exerted more influence on increasing lake water storage associated with rising temperatures.