Increasing flood risk under climate change and social development in the Second Songhua River basin in Northeast China

Study region: Second Songhua River basin (SSRB), Northeast China. Study focus: Accurately assessing future flood risks is the premise and foundation of flood control and water resources management. At present, studies are still lacking in assessing future water -shed flood risks that consider climate change and social development in Northeast China and the relative flood risk assessment framework. This study proposed an integrated flood assessment framework containing the AHP, entropy weight, and GCM downscaling methods, which was implemented in the SSRB, a typical watershed in Northeast China, to estimate future basin flood risks under climate change and social development. New hydrological insights for the region: The flood risk in the SSRB will increase significantly in the mid-term (2051-2075) and long-term (2076-2100) future. The areas under the four scenarios with greater than high-risk levels will expand by 28.9 %, 105.6 %, 165.6 %, and 156.7 %, respectively, compared to the historical scenario. The newly added areas mainly located in the lower reaches. Precipitation changes are the primary reason for the future flood risks. The increased GDP under a higher forcing degree will also significantly increase the flood risk in the long-term future in the lower reaches. Based on these above findings, extreme precipitation forecasting and flood management in downstream areas in the basin need to be enhanced. Energy-saving and emission-reduction measures should be simultaneously implemented.