Dynamic Changes in Lakes within the Selin Co Basin and Potential Drivers in Tibet

Abstract

\n 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 experienced significant expansion, 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 from 1988–2017, the areas of Bange Co and Cuoe Lake showed slow, overall increasing trends at rates of 0.28 km2/yr and 0.11 km2/yr, respectively, and they exhibited upward trends before 2005 but downward trends afterward. The area of Selin Co substantially increased by 685.8 km2 with a growth rate of 30.39 km2/yr, with a slow increase of 27.11 km2 during the period from 1988–1997, a rapid increase of 510.53 km2 from 1997–2005 and an increase of 148.16 km2 from 2005–2017. Accordingly, the lake level and water volume of Bange Co slightly increased by 1.64 m and 0.088 km3, respectively, whereas those of Selin Co significantly rose by 8.138 m and 17.47 km3, respectively. The changes in the areas of Bange Co and Cuoe Lake were mostly related to annual precipitation (AP). Enhanced glacial meltwater owing to rising, with a rapid reduction of 165.1 km2 (39%) in the glacier area in the basin between 1980 and 2010, predominantly drove the dramatic expansion of Selin Co, followed by accelerated permafrost degradation, with significant increases in the active layer thickness (ALT) (7.44 cm/yr) and soil temperatures at a 15-m depth (0.0346°C/yr).