Technical, Economic and Environmental Evaluation of Alternatives Under a Water Crisis Scenario: Desalination Versus Floodable Park

Objective: To evaluate, from technical, economic, and socio-environmental perspectives, two structural alternatives designed to mitigate water scarcity scenarios in the Camboriú River Basin and adjacent watersheds (Santa Catarina, Brazil): a seawater reverse osmosis desalination plant and a multipurpose floodable park. Theoretical framework: The study is grounded in the concepts of water security, water governance, Nature-Based Solutions, grey infrastructure, and multicriteria decision-making approaches applied to water resources planning in coastal basins under anthropogenic pressure and climate variability. Method: A multicriteria analysis model was applied, integrating technical, economic, and socio-environmental indicators. Variables were weighted by experts and local water governance stakeholders using ordinal scales and a magnitude–importance matrix for environmental impact assessment. Results and discussion: Results indicate that the floodable park shows better economic performance and relevant socio-environmental benefits but faces significant territorial constraints and structural interferences. The desalination plant achieved superior technical performance and a more homogeneous socio-environmental profile, particularly due to continuous water production and reduced pressure on freshwater sources. The integrated assessment identified desalination as the most strategic alternative under severe scarcity scenarios. Research implications: The findings support regional water planning processes and provide decision-making support for public managers responsible for water security in urbanized coastal basins. Originality/value: The study advances knowledge by comparatively assessing green and grey infrastructure within a single, replicable multicriteria framework, contributing to hybrid decision-making strategies in water resource management.