Uncovering stakeholder preferences for urban blue-green infrastructure siting: Insights from online swing weights elicitation

Blue-green infrastructure (BGI) location choice requires addressing objectives across environmental, ecological, urban, governance, economic and social domains, necessitating stakeholder engagement. However, preference elicitation in BGI planning often relies on single-disciplinary or expert-driven approaches that may overlook differences in priorities across stakeholder groups. The primary aim of this study was to understand stakeholder priorities for BGI planning objectives across three BGI groups: small systems (bioretention, infiltration systems, and swales), large systems (constructed wetlands and ponds/lakes) and urban trees, while the secondary aim was to test and advance a preference elicitation procedure using an innovative online swing-weighting software within a GIS-MCDA framework. Across two case studies in Quebec, Canada, 12 stakeholders in Trois-Rivières and 20 in Montréal representing government agencies, non-profit organizations, and research services, participated in five online workshops. They provided weights on an objectives-based BGI suitability framework. Results showed broad agreement on needs-related objectives (i.e. addressing site-specific needs that can be fulfilled through BGI placement), particularly water management, climate adaptation, and heat island mitigation, across BGI groups. Greater divergence emerged for opportunity-related objectives (i.e. leveraging site-specific opportunities), such as optimal soil type and planned works, reflecting differences in stakeholder priorities across BGI types and the potential of sites. By revealing shared and divergent planning priorities, this research highlights the value of stakeholder-driven preference elicitation and demonstrates the utility of swing weighting within GIS-MCDA for fostering transparent and participatory decision-making. Integrating stakeholder preferences into suitability mapping provides an approach for making differences in planning perspectives explicit and supporting context-sensitive BGI planning.