Ensuring Ecosystem Service Provision of Urban Water Nature-Based Solutions in Infill Areas: Comparing Green Factor for Districts and SWMM Modeling in Scenario Assessment

Abstract

Abstract This study aims to explore the measurement of potential synergies between water management objectives and other ecosystem services generated by Nature-Based Solutions (NBS) in the context of urban planning. The research also investigates the comparative benefits of two analytical methods, Storm Water Management Model (SWMM) and green area factor for districts (GAFD). The study employs Malmi district in Helsinki, Finland, as a case study, examining five distinct NBS scenarios with varying degrees of integration. The results affirm that NBS can indeed enhance ecosystem services provision and stormwater management. The comparative analysis of the two methods, reveals that scenarios with high green factors exhibit effective flood risk reduction, while those with low green factors struggle to manage water, emphasizing the importance of balancing green and built elements in urban planning for optimal flood risk reduction. Furthermore, the study underscores the advantages of the two methods: GAFD offers simplicity and lower expertise requirements, generating valuable insights into ecosystem services, while SWMM provides precise stormwater management data. The findings emphasize the significance of diverse NBS combinations that harness the multifunctional aspects of green infrastructure, highlighting the need for integrated urban planning. The utilization of GAFD analysis provides a comprehensive districtwide perspective in a flexible manner, thereby improving the comprehension of the interconnected nature of urban green spaces. Highlights Nature-based solutions (NBS) support urban stormwater management in infill areas. Green Area Factor for Districts (GAFD) is a practical tool to compare NBS options. GAFD and SWMM modeling results on stormwaters are comparable for common rain events. NBS size, quality and diversity reduce peak flows and enhance ecosystem services. Assessment of scenarios with the GAFD tool helps to identify multiple benefits of NBS.