Rising seas groundwater loss and urban expansion push Asia megadeltas toward crisis
Coastal flooding in Asia’s megadeltas is intensifying due to rapid urbanization, land use changes, excessive groundwater extraction, infrastructure development, and widespread sand mining. Since 1990, urban areas below five meters above sea level have expanded by over 70% in the Ganges-Brahmaputra-Meghna and Mekong deltas, and by at least 200% in the Chao Phraya delta.
The excessive withdrawal of groundwater has accelerated land subsidence in all five megadeltas, with sinking rates surpassing one centimeter per year. Additionally, intense river sand mining, driven by the high demand for construction materials, has contributed to severe erosion along riverbanks and coastlines.
Dams built upstream further disrupt natural river flows by trapping sediments that are essential for maintain...