Enhanced Monitoring of Lake Balkhash Water Level Dynamics in Central Asia Using Integrated GEDI and ICESat ‐2 Altimetry

Lake Balkhash, the third‐largest water body in arid Central Asia, is facing increasing concern as a result of recent declines in its water level. The Global Ecosystem Dynamics Investigation (GEDI) lidar, operational since April 2019 aboard the International Space Station, offers valuable data for measuring and monitoring inland water levels. However, GEDI‐derived elevation estimates are generally less accurate than those from radar or lidar altimeters dedicated to water‐level monitoring, exhibiting standard deviations ranging from 0.14 to 0.66 m compared to ICESat‐2's from 0.03 to 0.05 m. To leverage the temporal resolution of GEDI data while mitigating its limitations, this study integrates GEDI and ICESat‐2 satellite altimetry to investigate the water level dynamics of Lake Balkhash. A custom data processing protocol, including both global and local refinements, was applied prior to data integration. A gradient boosting machine (GBM) effectively reduced biases between the datasets, revealing a long‐term water level decline of 0.22 m/y over the period 2019–2023. In comparison to the Hydroweb and DAHITI datasets, the integrated product demonstrated improved consistency, temporal resolution and reduced noise. The integrated dataset showed good agreement with Hydroweb (RMSD of 0.32 m and R 2 of 0.89) and DAHITI (RMSD of 0.21 m and R 2 of 0.84), and exhibited superior stability, with intra‐annual standard deviations of 0.07–0.16 m. The distributed lag multivariate regression model showed that current‐month precipitation positively influenced water levels, while current‐month evaporation had a significant negative effect, with spring precipitation boosting levels and summer evaporation dominating water loss. These results indicate that this integrated satellite altimetry approach provides a robust tool for water resource monitoring and climate studies, particularly in data‐scarce regions.