A global framework for future costs and benefits of river-flood protection in urban areas

Floods cause billions of dollars of damage each year1, and
flood risks are expected to increase due to socio-economic development,
subsidence, and climate change2–4. Implementing
additional flood risk management measures can limit losses,
protecting people and livelihoods5. Whilst several models have
been developed to assess global-scale river-flood risk2,4,6–8,
methods for evaluating flood risk management investments
globally are lacking9. Here, we present a framework for
assessing costs and benefits of structural flood protection
measures in urban areas around the world. We demonstrate
its use under different assumptions of current and future
climate change and socio-economic development. Under these assumptions, investments in dykes may be economically attractive for reducing risk in large parts of the world, but not everywhere. In some regions, economically efficient
investments could reduce future flood risk below today’s levels, in spite of climate change and economic growth. We also demonstrate the sensitivity of the results to different assumptions and parameters. The framework can be used
to identify regions where river-flood protection investments should be prioritized, or where other risk-reducing strategies should be emphasized.