Mainstreaming nature-based solutions through five forms of scaling: Case of the Kiiminkijoki River basin, Finland.

Nature-based solutions (NBS) are considered as means to tackle climate change and biodiversity loss while simultaneously enhancing human well-being. Yet, it is still poorly understood how NBS could be mainstreamed. We address this gap by proposing a framework on NBS and employing it in Finland's Kiiminkijoki River basin through participatory workshops and a questionnaire. We examine socio-environmental challenges and visions, existing and emerging NBS to reach the visions, and ways to scale-up NBS to a river basin level. In the river basin, water quality is the priority challenge, due to its relationships with local culture, climate change, and biodiversity. Our results consider how (1) to ensure the relevance of NBS for local actors, (2) instrumental, intrinsic, and relational value perspectives can be enhanced simultaneously by NBS, and (3) site specific NBS can be mainstreamed (i.e., by scaling up, down, out, in, deep) to the river basin level and beyond.