Abstract

This study proposes guiding principles for flood risk mitigation by integrating Nature-based Solutions with the concept of Hydrological Interest Areas as a background for urban interventions. The methodological framework provides a matrix of joint urban and environmental planning recommendations, considering both physiographic characteristics and urban settlement patterns, along with a final program of necessities. Using the Bambu River Watershed in Maricá, Rio de Janeiro, Brazil, as a case study, the research evaluates three urban planning scenarios against the current situation. The Uchronic Scenario represents an idealized flood-free urban development, whereas the Current Situation reveals that nearly 21% of properties are in flood-prone areas. The Desirable Scenario involves extensive relocations, while the Realistic Scenario applies feasible open-space interventions, protecting 2,243 lots during a 25-year event. The findings confirm that integrating Hydrological Interest Areas and Nature-based Solutions is an effective strategy to enhance flood resilience while addressing social and environmental challenges.