Assessing resilience of water security in global megadeltas

Global mega-river deltas host a disproportionate share of the world’s population and economic activity, yet they are increasingly exposed to compounded water security risks arising from climate change, upstream regulation, and rapid socioeconomic transformation. Despite their global importance, a consistent and comparative assessment of water security sustainability across deltas remains limited.

Here, we develop an integrated assessment framework to evaluate the sustainable water security of major global river deltas by jointly considering hydrological availability, climate extremes, water demand, and socioeconomic pressure. Using multi-source datasets on river discharge, precipitation and temperature, population distribution, economic activity, and land use, we quantify spatial and temporal patterns of water stress across representative deltas in Asia, Africa, Europe, and North America. Trend analysis and attribution methods are applied to disentangle the relative contributions of climatic variability and human drivers to observed changes in water security.

Our results reveal pronounced regional heterogeneity. Many Asian and African deltas exhibit increasing water insecurity driven by the combined effects of declining upstream inflows, intensifying drought extremes, and rapidly growing domestic water demand. In contrast, deltas in developed regions show relatively stable water availability but remain vulnerable due to high exposure and dependence on engineered water systems. The analysis further highlights critical hotspots where climate change amplifies existing socioeconomic pressures, posing challenges to long-term sustainability.

This study provides a global, delta-scale perspective on water security sustainability and identifies priority regions for adaptive management. The framework offers a transferable tool to support policy-relevant assessments and inform integrated water governance strategies for vulnerable delta systems under future change.