Ongoing Drainage Reorganization Driven by Rapid Lake Growths on the Tibetan Plateau

Abstract

Drainage reorganization generally occurs on geological time scales under unstable river network conditions. A few local‐scale studies indicate that recent climatic changes might accelerate the drainage reorganization process. However, large‐scale drainage reorganization during the modern era is rarely documented. This study examines ongoing drainage reorganization on the endorheic Tibetan Plateau (TP) as a primary result of drastic lake expansion. A total of 11 drainage system reorganization events comprising 24 different lake basins and covering a total area of 61,115 km2 occurred between 2000 and 2018. Assuming the continued growth rate of TP lakes, we project another 20 basins will be reorganized before 2030. These drainage basin reorganizations not only alter hydrological processes in the endorheic TP but may also cause the endorheic‐exorheic transition, leading to the upstream sprawl of the Yangtze River Basin and posing outburst flooding risks on China's key infrastructure such as the Qinghai‐Tibet Railway.

Spatiotemporal variations and overflow risk analysis of the Salt Lake in the Hoh Xil Region using machine learning methods

“…In the calculation formula, ΔV represents the change of lakewater volume in two periods, A 1 and A 2 represent the area of the lake in different periods, respectively, with lake area A 1 and level H 1 for the previous period and lake area A 2 and level H 2 for the later period. This method has been frequently used in estimating lake water volume (Liu et al, 2021;Lu et al, 2021).…”

“…Although these reorganization events occurred in the endorheic basins, the results showed that the significant increase in the Salt Lake water volume could overflow to the adjacent exorheic basin, seriously threatening the engineering construction. In the worst-case scenario, the outburst flood from Salt Lake can destroy engineering infrastructure within 6 hours (Liu et al, 2021). In the end, to reduce the impact of the potential Salt Lake outburst, the local government constructed a drainage channel to divert the lake water into the Qingshui River, which also led to the endorheic-exorheic transition (Lu et al, 2021).…”

“…The imbalance between liquid (lakes and rivers) and solid (snow and glaciers) water has augmented since the 1980s, together with glacier retreat, lake water gain, and increasing runoff (Yao et al, 2022). Changes in hydrology and geomorphology caused by this imbalance affect drainage pattern reorganization and trigger the endorheic-exorheic transition, threatening the ecosystem and infrastructures (Milner et al, 2017;Liu et al, 2021). For example, In mid-September 2011, the Zonag Lake in the Hoh Xil region burst, causing a large amount of lake water to overflow, resulting in a sharp reduction in the area of the Zonag Lake, accompanied by the formation of permafrost in the following years (Liu et al, 2016;Zhang et al, 2022).…”

Widespread declines in water salinity of the endorheic Tibetan Plateau lakes

“…However, the lakes with the most remarkable level-rising rates behavior in locally inconsistent patterns, which are found in several medium-sized basins (Salt Water Lake: 35.61 m, Yibug Caka: 20.30 m, and Xuejing Lake: 17.83 m) around the western and middle Kunlun Mountains. Another exception is Salt Lake, which had an abnormal rise of 16.27 m in water level due to the substantial upstream water supply from the Zhuonai Lake outburst (Liu et al 2016, Liu et al 2021b. Of the 160 lakes examined, 121 and 39 are endorheic and exorheic lakes, respectively (table S1 (available online at stacks.iop.org/ERC/4/091002/mmedia)).…”

“…That was because this small and shallow lake experienced more than 16 m level rise and 4.5 times area expansion after the upstream lake outburst in 2011. Its salinity would get much lower as the Chinese government constructed an artificial channel in 2019 and made it become an outflow lake, being linked with the upstream Yangtze (Liu et al 2021b, Lu et al 2021. Other lakes that experienced obviously reduced salinity include Norma Co (43.40 g l −1 to 4.91 g l −1 ), Cedo Caka (168.39 g l −1 to 19.50 g l −1 ), Serbug Co (28.35 g l −1 to 4.31 g l −1 ), Dogaicoring Qangco (266.35 g l −1 to 42.00 g l −1 ), and Angdar Tso (180.87 g l −1 to 32.50 g l −1 ), etc.…”