Despite a recent global decline in the volume of endorheic water bodies, lakes in the interior Tibetan Plateau (ITP) have expanded remarkably since the mid-1990s. Climate change and intensified cryospheric melting may have driven this growth; however, the underlying hydrological processes and the role of cryospheric change remain largely unclear at present because challenging terrain conditions hinder observations of complex interactions among the atmosphere, cryosphere, and hydrosphere in high-mountain lake basins.
The ITP possesses more than 60% of the total lake water storage across the Tibetan Plateau (TP). Due to its large area and sparse observations in the ITP, scientific knowledge on basin hydrology and lake water balance is still limited. In recent decades, significant glacial retreat, snowmelt and frozen soil thawing caused by climate warming have modified the region’s complex hydrological regimes.
To enhance the understanding of the drivers of lake changes in the ITP, team of environmental change and multi-spheres processes (Institute of Tibetan Plateau Research, Chinese Academy of Sciences) and collaborators examined the water budgets of the ten largest endorheic lakes (area larger than 500 km2) in the ITP (Fig.1a), by simulating hydrological cycles at the lake-basin scale. A physically-based, distributed cryosphere-hydrology model (WEB-DHM-SF, coupled with a three-layer snow module and frozen-ground physics scheme) was deployed, hydrological processes and lake water storage changes (LWSC) in the ten lake basins were investigated over a long-term (1979~2016) hydrological simulation, verification (using in-situ observations and remote sensing data) and comprehensive evaluation. The main drivers of lake expansion were quantitatively investigated.
The results indicated that the total water volume of the ten lakes increased by 58.70 km3 from 1979 to 2016, with turning points (transition years) mostly occurring around 1995 (Fig.1b). The contributions of rainfall-runoff, lake surface precipitation, snow and glacier meltwater, lake surface evaporation and soil freeze-thaw to LWSC were in the ranges from 60.2%~76.4%, 13%~29.7%, 20.5%~45.4%, -38.4%~ -15.7% and 2.1%~6.7%, respectively (Fig.2). Precipitation (i.e., the sum of rainfall-runoff and lake surface precipitation) was the dominant factor of lake expansion, while the contributions of snow and glacier meltwater increased after transition years in most lakes. The contributions of different components also showed regional differences. Sensitivity analysis showed that soil freeze-thaw processes have promoted the recent lake expansion in the ITP.
This study quantitatively assessed the lake volume changes and their driving mechanisms in the ITP, and provided an important scientific basis for deeper insights into the role of internal hydrological processes of lake basins and the changing cryosphere in shaping the lake expansion.
The above research were published in the international journal “Science Bulletin” with the title of “Quantifying the major drivers for the expanding lakes in the interior Tibetan Plateau”. The first and corresponding author is Dr. Zhou Jing, and the co-corresponding author is Prof. Wang Lei. This study was financially supported by the National Natural Science Foundation of China (41771089, 41988101), the “Strategic Priority Research Program” of the Chinese Academy of Sciences (XDA19070301), and the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (2019QZKK020604).
Figure 1 Locations of the ten studied lakes across the interior Tibetan Plateau (a), and their simulation-based annual lake water storage change (LWSC) from 1979 to 2016 (b).
（①: Nganglaring, ②: Zharinamco, ③: Tangra Yumco, ④: Seling Co, ⑤: Nam Co, ⑥: Dorsoidongco and Chibzhang Co, ⑦: Ulan Ula Lake, ⑧: Xijir Ulan Lake, ⑨: Aqikekule Lake, ⑩: Ayakeku Lake.）
Figure 2 The contributions of different components to LWSC of the ten lakes across the interior Tibetan Plateau from 1979-2016.
Article information：Zhou J*., Wang L*., Zhong X., Yao T., Qi J., Wang Y., Xue Y. Quantifying the major drivers for the expanding lakes in the interior Tibetan Plateau. Science Bulletin, 2022, 67(5): 474-478.