Residual flood damage under intensive adaptation

The risk of river flooding is expected to increase with climate change and socioeconomic development, and therefore additional protection measures are required to reduce the potential for increased flood damage. While studies have investigated the effectiveness of adaptation measures to reduce flood risks, none has evaluated residual flood damage (RFD), which reflects the projected increase in damage under intensive adaptation. Here we evaluate RFD under several adaptation objectives using an inundation model incorporating damage estimates and a cost–benefit analysis, and estimate that China, India and Latin American countries can achieve higher levels of flood protection that will reduce RFD even under extreme scenarios. However, a high RFD (exceeding 0.1% of subnational administrative gross domestic product) remains, especially in eastern China, northern India and central Africa. RFD could be reduced with shorter construction periods or lower adaptation costs, implying the need for immediate and appropriate adaptation actions, including enhanced financial support for high-risk regions.