Evaluating supply and demand relationship of urban flood regulation service and identifying priority areas for green infrastructure implementation in urban functional zones

Balancing the supply and demand of flood regulation services (FRS) in urban ecosystems is crucial for urban flood management. However, FRS supply-demand relationship in urban functional zone is less concerned, and future changes for urban FRS under climate change scenarios remain unclear. This study analyzed the relationships of FRS supply-demand and identified priority areas for green infrastructure implementation at the urban functional zone scale. Results showed the deficient area of FRS supply totally occupies 36.1 % of the study area. FRS supply-demand matching degree was mainly distributed in the surplus zone (high supply, low demand). Commercial zone and residential zone have the highest number of units with the FRS deficit zone (low supply, high demand), while green space zone have the highest number of units with the FRS surplus zone. Under the climate change scenarios, FRS supply showed a declining trend from 10-year to 100-year storm events (0.28–0.21, 0.26–0.22 for the SSP2-4.5 and SSP5-8.5 scenarios, respectively); while the changes in the averaged FRS supply-demand ratio values caused by climate change increased as the return period increased (from −0.69 % to −4.36 % and from −1.48 % to 2.55 % under the SSP2-4.5 and SSP5-8.5 scenarios, respectively). The area proportion of residential zone units located in the high priority level for green infrastructure implementation was 51.8 %, and the area of commercial zone units located in the high priority areas accounts for 38.4 %. These results could promote understanding FRS supply-demand relationship in urban areas, and provide potential implications for urban flood mitigation measures.