Quantitative analysis of water balance and the driving forces for Yan
lake expansion from 2015 to 2018 in the Hoh Xil region, Tibetan Plateau
Abstract
Accelerated expansion of the Yan Lake basin since 2010 has been
confirmed by dramatic increases in area determined by remote sensing
images and measurements of rapid water level rise (2015–2018). However,
the underlying causes of this expansion remain unclear. In this study,
lake area, water levels, and volume fluctuations were investigated and
the water balance reconstructed. The results showed the Lake Yan area,
water level, and volume increased to 59.9 km2, 7.91 m, and 14.17 Gt,
respectively, by 2018, with 60%–70% of the increase during August to
October within 1 yr. Over the past 40 yrs, lake area, level, and volume
of lake Yan varied in three stages: slight increase (1980s–2011), rapid
increase (2011–2013), and steady increase (2014–2018). A Mann-Kendall
analysis suggested that precipitation and air temperature continuously
increased at 2.22 mm yr-1 and 0.05°C yr-1, respectively. As for the
glacier, meltwater was 1.0±0.2 Gt and accounted for a smaller proportion
of the lake water supply. The lake water balance identified increased
net precipitation as the dominant factor (71%) for the increase in lake
water storage, followed by groundwater (16%) and glacial meltwater
(15%). These estimates provide the first quantitative evaluation of the
water balance components in the Yan Lake basin, which could provide
insights into the responses of Tibetan lake dynamics to climate change.