Investigating rapid lake expansion and water budget through multi-source remote sensing data in the Eastern Kunlun Range region on the Tibetan Plateau

Eastern Kunlun Range of the Tibetan Plateau, situated in the westerlies–monsoon transition zone, has experienced significant hydrological changes in recent decades. Rapid lake expansion together with GRACE-derived terrestrial water storage anomalies indicate the largest regional water gain on the Plateau. To assess lake budgets and contributing components, three major endorheic basins were investigated from both lake water balance and basin-scale mass balance perspectives. Lake volume variations were derived from ICESat-1/2 altimetry and Landsat-based area; permafrost meltwater was quantified using SBAS-InSAR-derived ground deformation from ascending and descending Sentinel-1 data; glacier mass balance was estimated from TanDEM-X and SRTM DEM differencing, validated by ICESat-2; and GRACE mascon products quantified basin-scale water storage. Results show accelerated lake expansion since the early 2010s. From 2017–2022, lake volumes rose by 397.3 ± 10.0, 375.9 ± 14.5, and 143.7 ± 5.6 × 10 6 m 3 /yr in the Ayakkum, Aqikkule, and Jingyu lake basins, respectively. Permafrost thaw supplied 54.9 ± 12.0, 32.3 ± 5.5, and 15.6 ± 3.8 × 10 6 m 3 /yr, accounting for 8.6 %–13.8 % of lake gains. In contrast, glaciers exhibit near-equilibrium to slightly positive storage tendencies, indicating a limited contribution from excess glacier-meltwater runoff. Both the lake-based water-balance closure and the GRACE-constrained watershed-scale mass balance consistently identify enhanced basin-wide net precipitation as the dominant driver of recent lake expansion. • Revealed rapid lake expansion in Eastern Kunlun Range region and its main drivers. • Clarified water budget dynamics in data-scarce endorheic lake basins. • Quantified excess glacier and ground ice meltwater contributions to lake expansion. • Identified substantial precipitation increase in westerlies–monsoon transition zone.