Estimation of lake water storage and changes based on bathymetric data and altimetry data and the association with climate change in the central Tibetan Plateau

Lake water storage is an important factor in analyses of lake water balance. However, it is difficult to calculate the water storage of lakes on the Tibetan Plateau due to the lack of bathymetric data. Lake water storage and changes in Chibuzhang Co (CC) and Duoersuodong Co (DC), which are located in an endorheic system and have been connected since 2006, were estimated based on in situ bathymetric data, satellite altimetry data and Landsat images of the central Tibetan Plateau. In 2016, the maximum depth and water storage of DC were 68.7 m and 12.2 ± 1.72 km3, respectively, with an area of 490.2 km2, and those of CC were 116.3 m and 16.2 ± 2.27 km3, respectively, with an area of 575.4 km2. The total lake water storage in DC and CC increased by 24.5% (2.4 km3) and 14.1% (2 km3) from 2003 to 2014, respectively, based on satellite altimetry data and Landsat images using an empirical equation. The relationship between lake changes and meteorological factors indicated that both increased glacial meltwater and increased precipitation were important drivers of each lake's expansion and that a small increase in evaporation (2.5 mm/y) had little negative impact on lake expansion (0.41 m/y). Heterogeneous changes in the two lakes from 1993 to 2005 were mainly due to water from CC supplying DC through a channel, and the lake level of DC was always lower than that of CC until 2006, indicating that the geological conditions around both lakes were also an important factor in the lake changes. The assumption was that all glacial meltwater from the Puruogangri and Geladandong glaciers was supplied to the two lakes through runoff with minimal evaporation, and glacial meltwater made an approximately 19.3 ± 4.5% contribution to the lake expansions (0.4 km3/y) of DC and CC from 2003 to 2014 based on the results of the glacier mass balance.