Accounting for crustal deformation in the estimation of lake water storage in the Aral Sea region

Modern geodetic techniques reveal that large lake water changes can induce significant crustal deformation, yet most studies overlook crustal deformation that alters lakebed geometry and biases water storage estimates. Using InSAR, satellite gravimetry, and satellite altimetry, we assess lake volume changes in the Aral Sea region from 2006 to 2020. Our results show that four major Aral lakes lost ~5200 Mt of water, accounting for ~37% of the total terrestrial water storage decline in the region. InSAR reveals cumulative uplift of 12.2 ± 0.4 mm, but notably, desiccation-induced rebound cannot fully explain the signal, as ~25% of the deformation is driven by global far-field mass redistribution. Projected onto lakebeds, uplift biases water storage estimates ranging from 2% to 54%, equivalent to 178.2 Mt of apparent water mass. Neglecting these effects systematically underestimates water loss, with the northern sub-basin alone showing more than half of the altimetry-derived decline masked by uplift.