Urban ecohydrology under socioeconomic scenarios: The protagonism of nature-based solutions in a changing future

Urban ecohydrology research has assessed how several drivers interfere with the basin's response. These interactions can be utilized in urban basins to enhance flood risk management. This paper aims to show how socioeconomic narratives influence rainfall-runoff transformation under changing conditions. For this, the study used the Millennium Ecosystem Assessment (MA) scenarios to measure the influence of different storylines on the land cover and, consequently, the basin's response, measured as the Percentage of Peak Flow Variations (PPFV) of the starting scenario. MA scenarios consider postures reactive and proactive to solve problems and different levels of the protagonist of nature. We used 13 urban ecohydrological variables that are sensitive to the socioeconomic narrative and include the use of Nature-based Solutions (NbS). Then, we set up the qualitative scenarios to apply in two Brazilian urban basins (78.00 and 15.42 km²) to create quantitative scenarios. Finally, we used rainfall-monitored events in these basins and registered their responses as PPFV. The results indicated that socioeconomic narratives significantly impacted the urban basins. PPFV medians ranged, in the reactive scenarios, between 259 % and 70.5 %, and in the proactive scenario, between 54.5 % and -47.5 %. The scenario with NbS in their narrative shows significant decreases in the two basins. We concluded that socioeconomic narratives influence urban flood risk management. Societies with international cooperation focused on environmental solutions, such as using NbS, achieve better adaptation to challenging futures in the face of hydrological threats than reactive societies that do not prioritize the environment.