Building resilience in Asian mega-deltas

The five Asian mega-deltas (the Yangtze, the Pearl, the Chao Phraya, the Mekong and the Ganges–Brahmaputra–Meghna deltas) are home to approximately 80% of the global deltaic population and the region experiences 90% of global flood exposure. In this Review, we investigate the similarities and differences between the Asian mega-deltas to identify transferable lessons to improve climate resilience. The deltas are increasingly threatened by coastal flooding, saline intrusion and erosion caused by climate change and human activities such as groundwater extraction and dam construction. Owing to differences in the stages of their development, various resilience measures have been implemented. For example, the Ganges–Brahmaputra–Meghna and Mekong deltas use strategic delta plans to identify risk hotspots and guide decision-making. These deltas also increase resilience at a community level by supporting communities to diversify their livelihoods to respond to changing risks and land conditions. Meanwhile, the Yangtze and Pearl deltas have developed forecasting and sensing technologies to allow them to prepare for and respond to hazards effectively. The Asian mega-deltas should learn from one another to integrate effective resilience plans across regional, delta and community levels. Future cross-delta collaborations and knowledge transfer, for example through the formation of a Regional Delta Resilience Alliance, could help to achieve long-term sustainable delta management.