Dynamic changes in lakes and potential drivers within the Selin Co basin, Tibetan Plateau

摘要

Prevailing lake changes on the Qinghai-Tibetan Plateau (QTP) have occurred. Selin Co, a representative saline lake in the central region of the QTP, has had the largest increase and become the largest endorheic lake in Tibet, but the main cause for its dramatic expansion is still under debate. Based on Landsat images, meteorological data and glacier and permafrost data, the dynamic changes in Selin Co and its surrounding small lakes were systematically discussed, and the driving factors behind these changes were further explored. The results suggest that during 1988-2017, the areas of Bange Co and Cuoe Lake showed slow, overall increasing trends at the rates of 0.28 km(2)/year and 0.11 km(2)/year, respectively, and upward trends before 2005 but downward trends afterward. The area of Selin Co substantially increased by 685.8 km(2) with a growth rate of 30.39 km(2)/year, with a slow increase of 27.11 km(2) during the period of 1988-1997, a rapid increase of 510.53 km(2) during 1997-2005 and an increase of 148.16 km(2) during 2005-2017. Accordingly, the lake level and water volume of Bange Co slightly increased by 1.64 m and 0.088 km(3), respectively, whereas those of Selin Co significantly rose by 8.138 m and 17.47 km(3), respectively. The changes in the areas of Bange Co and Cuoe Lake were mostly related to annual precipitation (AP). The expansion of Selin Co may be partly explained as the discharge from the glacier retreat and permafrost degradation in the watershed. Glacial meltwater has enhanced owing to rising, with a rapid reduction of 165.1 km(2) (39%) in the glacier area in the basin between 1980 and 2010. Permafrost degradation has significantly accelerated, with increases in the active layer thickness (ALT) (7.44 cm/year) and soil temperatures at a 15-m depth (0.0346 degrees C/year).