This thesis tackles the pressing need to enhance our comprehension of how urban nature-based solutions (NBS) can have a wide array of desired and undesired impacts. Despite NBS being promoted in urban agendas as versatile tools to address urban and global challenges, the assessment of their impacts remains understudied. This deficiency results in an incomplete understanding of the potential synergies and trade-offs that NBS could be producing both within and beyond urban spaces. For this matter, this thesis critically examines the current state of assessments of urban NBS impacts and proposes a path forward for their improvement. I first portray the scope of NBS impacts within complex urban environments, showing their connections to sustainability, resilience, and equity challenges. I illustrate how the interactions between these challenges can lead to both desired and undesired outcomes, highlighting the complexity of anticipating NBS impacts. Furthermore, I review existing evaluation approaches and identify the key limitations among them. Based on these, I argue for adopting a vulnerability-focused approach to enhance NBS impact evaluation. Next, I introduce a framework for assessing NBS impacts that go beyond traditional approaches centered on environmental impacts and ecosystem services. This framework evaluates the extent to which NBS alter local-scale vulnerabilities (within urban areas), employing spatial indicators (exposure/sensitivity) and multi-criteria decision analysis to integrate them. To demonstrate its effectiveness, I apply this framework to the case study of the Metropolitan Area of Barcelona, assessing the impacts of increasing (peri-)urban agriculture on critical vulnerabilities. The results reveal diverse spatial outcomes and trade-offs in urban vulnerabilities, influenced by both the quantity and location of (peri-)urban agriculture Building upon this, I extend the vulnerability framework to assess impacts across different spatial scales. This involves evaluating NBS impacts on local-scale vulnerabilities and on broad-scale vulnerabilities. The latter are assessed by considering their effects on planetary boundaries. I apply this extended framework to the case study of extensive green roofs in Oslo. This approach offers a novel and integrated understanding of NBS cross-scale trade-offs and synergies and allows to produce spatially explicit outcomes depicting optimal NBS configurations where the desired NBS impacts are maximized while undesired minimized. This research contributes to enhancing NBS planning dynamics by offering both theoretical and practical insights into how urban NBS can simultaneously produce desired and undesired effects within and beyond urban environments. Through linking NBS impacts to vulnerabilities, the tested NBS-vulnerability framework presents a versatile and replicable methodology for further assessing urban NBS. This novel approach holds value for urban policy and planning as it enables an integrated, cross-scale, and site-specific assessment of NBS aligned with urban agendas, thereby reducing uncertainties and bridging the gap between short-term and long-term impacts.
The impacts of urban nature-based solutions: An integrated spatial vulnerability perspective
Camacho Caballero, D. A. (Author). 28 Jun 2024
Student thesis: Doctoral thesis
Student thesis: Doctoral thesis