Hydrology and Earth System Sciences | 2021
Contrasting hydrological and thermal intensities determine seasonal lake-level variations – a case study at Paiku Co on the southern Tibetan Plateau
Abstract
Abstract. Evaporation from hydrologically closed lakes is one of the largest components\nof the lake water budget; however, its effects on seasonal lake-level variations\nremain unclear on the Tibetan Plateau (TP) due to a lack of comprehensive\nobservations. In this study, weekly lake evaporation and its effects on\nseasonal lake-level variations are investigated at Paiku Co on the southern TP\nusing in situ observations of thermal structure and hydrometeorology\n(2015–2018). Lake evaporation from Paiku Co was estimated to be 975±142 mm during the ice-free period (May to December), characterized by\nlow values of 1.7\u2009 ± \u20090.6\u2009 mm\u2009d−1 during the pre-monsoon season (May to June), high values of\n 5.5±0.6 mm\u2009d−1 during the post-monsoon season (October to\nDecember), and intermediate values of 4.0±0.6 mm\u2009d−1 during\nthe monsoon season (July to September). There was a ∼ \u20095-month lag between\nthe maximum net radiation (June) and maximum lake evaporation\n(November). These results indicate that the seasonal pattern of lake\nevaporation from Paiku Co was significantly affected by the large lake heat\nstorage. Contrasting hydrological and thermal intensities may play an\nimportant role in the large amplitude of seasonal lake-level variations at\ndeep lakes like Paiku Co. High inflow from monsoon precipitation and glacier\nmelting and moderate lake evaporation, for instance, drove rapid lake-level\nincrease during the monsoon season. In contrast, high lake evaporation and\nreduced inflow caused lake level to decrease significantly during the\npost-monsoon season. This study implies that lake evaporation may play an\nimportant role in the different amplitudes of seasonal lake-level variations\non the TP.