Stakeholder engagement as a key element in defining basin-scale Safe Operating Spaces (SOS) for freshwater resilience

Freshwater ecosystems worldwide are under growing pressure from climate shifts, land use changes, and competing demands for water resources. Transboundary river basins face additional complexities due to diverse cultural, economic, and political contexts. As resource availability fluctuates and extreme events become more frequent, it becomes essential to identify strategies that safeguard both ecological integrity and human wellbeing. A Safe Operating Space (SOS) framework offers a way to define ecological and socio-economic boundaries that help preserve long term resilience in freshwater systems. Approaches for establishing an SOS often rely on multiple lines of scientific and modellingbased evidence to determine thresholds for, e.g., flow regimes, water quality, and ecosystem health. Yet stakeholders at the local level bring critical insights into trade-offs, priorities, and governance challenges that extend beyond technical assessments. In transboundary river basins, the perspectives of communities, policymakers, water users, and other stakeholders are especially valuable. They contribute grounded knowledge about issues such as balancing flood protection, agricultural productivity, and biodiversity conservation. When these viewpoints are included in defining an SOS, basin level targets become more responsive to real world conditions and more likely to gain broad acceptance. Stakeholder engagement also supports inclusive decision making and productive knowledge exchange. Structured processes, including multi-criteria evaluations and facilitated discussions, help participants identify priorities, and then find consensus on boundaries that integrate scientific evidence with regional needs. This integrated approach enables effective monitoring and adaptation when basins experience changes in climate, land use, or political contexts. Within the Horizon Europe SOS-Water project, stakeholder workshops in the Mekong and Danube basins revealed the necessity of capturing distinct socio-economic realities and local knowledge. Participants highlighted varied concerns, ranging from supporting flood-dependent livelihoods and food security to safeguarding ecological connectivity and effective water allocations, reinforcing the value of stakeholder-driven processes. By involving those most affected by environmental decisions, the SOS framework becomes a cooperative tool for sustainable water governance. Individuals and institutions who help define boundaries and thresholds are more inclined to uphold them, support necessary interventions, and adjust strategies over time. Through this feedback loop, ecological and socio-economic systems both benefit, strengthening the capacity of basins to navigate future uncertainty.