What drives the rapid water-level recovery of the largest lake (Qinghai Lake) of China over the past half century?

Abstract

Qinghai Lake (QHL), the largest saline lake in China, is located in the Tibetan Plateau. The lake plays an important role in regional water and nutrient cycles and the sustenance of semi-arid ecosystem functions. Over the past half century, the lake experienced substantial changes in its water level in a seesaw pattern. In the first 35 years, the lake level presented a dramatic continual decrease of 2.63 m, then a reversed upward tendency appears beginning the early 21st century. The water level in the recent years has recovered to the stage from 50 years ago (around 1970). However, the driving factor causing the seesaw pattern changes remains to be unclearly understood. The goal of this study is to investigate the abnormal changes in the water level of the QHL from 1970 to 2018 and explore the primary contributor of the reversed shifts by taking the climate-driving view. Then, we discuss the possible atmospheric circulations that are tightly associated with the climate variables over the QHL catchment and its surroundings. Results show that the rapid water-level recovery of the QHL in recent years is attributable to the substantial increases in water levels in several key abnormal wet years of 2005, 2012, 2015, and 2017/2018. The lake level variations coincide with annual precipitation rather than temperature and evaporation. Besides, this study reveals that the atmospheric water vapor flux in the QHL basin is mainly transported from the west and southwest to the east. For the anomalous high-precipitation (wet) years, the total water vapor of the QHL basin increases significantly. The ENSO and other atmospheric circulation factors may be related to the precipitation variations that drive the water vapor transport of the QHL basin.