Stakeholder-Driven Prioritisation of Nature-Based Solutions in a Volcanic Lake Basin

Soil erosion, surface runoff, and nutrient losses are critical processes linking environmental degradation with social and economic pressures, particularly in multifunctional landscapes where agricultural production, ecosystem conservation, and local livelihoods coexist. In such contexts, the effectiveness of Nature-Based Solutions (NBS) depends not only on biophysical performance but also on their social feasibility and acceptance. This study explores how structured science–society interaction can support participatory planning of NBS in an erosion-prone socio-ecological system.The research is developed within the Horizon Europe EUROLakes project and focuses on the Lake Vico volcanic basin (Central Italy), a unique landscape where high natural value, hazelnut cultivation, and strong cultural, recreational, and identity-related ties to the lake coexist. Increasing erosion-driven runoff and nutrient transport are contributing to declining water quality and eutrophication, highlighting the urgent need to balance human pressures and ecosystem functioning to avoid further degradation of the lake’s water ecosystem.Environmental analyses of erosion processes and nutrient pathways were used as a shared knowledge base to support dialogue with local actors. Stakeholder mapping, workshops, and focus groups were adopted as key methodological steps to identify feasible management interventions and alternative scenarios aimed at improving water quality and erosion issues, while preserving community identity and agricultural productivity. Building on this process, a participatory workshop was conducted using a digital Participatory Multicriteria Analysis (PMCA), implemented through a tailored version of the consolidated MULINO Decision Support System (mDSS), and structured around the 4 Returns Framework to jointly evaluate NBS-oriented options across natural, social, financial, and inspirational returns.Preliminary results from the participatory assessment contributed to the identification of priority intervention themes and informed the evaluation of alternative management options within the EUROLakes project. By integrating scientific indicators with experiential and place-based knowledge within a single decision-support process, the approach makes trade-offs explicit and fosters collective learning. The study contributes to interdisciplinary debates by demonstrating how environmental and social sciences can jointly support the co-design of context-sensitive NBS in sensitive lake landscapes