Planning the multifunctionality of nature-based solutions in urban spaces

Urban infrastructure is under substantial stress due to climate change and urbanisation. More frequent flooding events and heat waves in cities threaten citizens' health and wellbeing. Current infrastructure is mostly based on grey solutions, focusing on only one function. Nature-based solutions (NBS), which are supported by nature and mimic natural processes, are multifunctional and can provide several benefits at the same time. However, this multifunctionality is deficiently considered during planning of urban infrastructure transitions. This work presents a method to help urban NBS planning processes considering multiple climate adaptation objectives. It is a 3-steps GIS-based multi-criteria method, in which the first step is a "priority areas identification", the second step is a "site-specific NBS allocation", and the third step is a "multifunctional performance evaluation". The method was applied to a case study to demonstrate its operation and validate the outcome with stakeholders. This work helps to improve the planning of multifunctional NBS in cities considering local needs, spatial opportunities, and site-specific limitations. Furthermore, it allows to assess the trade-offs among multiple NBS benefits when more than one objective is pursued.