Proactive intervention of green infrastructure on flood regulation and mitigation service based on landscape pattern

Abstract

Green infrastructure (GI) could reduce surface runoff and provide essential ecosystem service (ES) in flood management. More frequent flooding necessitated GI intervention to promote flood regulation and mitigation service. This study presented the Supply-Demand-Intervention framework of ES for flood mitigation in Nanjing, and aimed to explore flood interventions of GI that improve ES supply and satisfy ES demand from the perspective of landscape pattern. This study quantified ES supply by runoff reduction capacity and assessed ES demand by flood risk index, respectively. Stepwise regression analysis revealed the association between landscape pattern and ES supply and demand. We found the mismatch between ES supply and demand in Nanjing, as well as the spatial heterogeneity between ES supply and demand during various design storms. Urban central areas showed the low ES supply, high ES demand and high priority rank of intervention. Current GI conditions had the difficulty in dealing with more severe floods in Nanjing. And landscape elongation, shape, fragmentation, and segmentation were found to have significant effect on ES supply and demand. More elongated and segmented landscape, with less continuity and connectedness, could promote ES supply, while less fragmentated landscape, with complex shape, could reduce ES demand. Different intervention strategies were proposed to adapt to different areas for promoting ES delivered by GI. In Gulou and Qinhuai district, it was suggested to apply well-shaped elongated cropland and water areas to segment and disperse the built-up land. These findings could provide critical implications for reasonable GI planning and management in flood mitigation and adaption.