Global Study Reveals Rapid Land Subsidence in Major River Deltas Threatening Millions

Tue, 21 Apr 2026 08:46:00 +0200

A comprehensive global study led by Leonard Ohenhen and Virginia Tech researchers has found that many of the world's largest river deltas are sinking faster than rising sea levels, putting over 236 million people at risk of flooding. Using high-resolution satellite radar mapping, the study analyzed 40 major deltas across five continents, revealing localized patterns of subsidence driven primarily by human activities such as intensive groundwater pumping, reduced sediment flow, and rapid urbanization. Some deltas, including the Mekong, Nile, Ganges-Brahmaputra, Mississippi, Chao Phraya, and Yellow rivers, are experiencing particularly severe elevation loss. The research highlights that in 18 of these deltas, the rate of subsidence already exceeds the pace of local sea-level rise, demonstrating that the threat is immediate rather than distant. Groundwater depletion is identified as the most significant factor, although the main driver varies regionally. The findings underscore the import