Potential Impacts of Land Use Changes and Climate Variations on Flows in a Basin in Northeastern Brazil

The present study sought to evaluate the sensitivity of several ecologically relevant flow parameters to land use changes and climate change. The study was carried out in the Cachoeira River Basin located in the Atlantic Forest biome with predominately agricultural activities in its drainage area, in the state of Bahia, Brazil. To achieve the proposed objective, the Soil and Water Assessment Tool (SWAT) model was used to calibrate and validate the historical flow series from 1985 to 2015, create the simulation scenarios, and subsequently evaluate the hydrological changes in the different scenarios proposed through the 19 indices in the Indicators of Hydrologic Alteration (IHA) software. The results reveal that the maximum flows of 30 and 90 days, as well as the number of reversals, will be the most affected by future climate conditions. These significant changes indicate that the flows are mainly linked to changes in precipitation patterns in the basin. Thus, the negative medium and long-term trend of these flows can alter the availability of water in the basin and affect not only aquatic life but also the socio-economic development of the basin, with consequences for the water supply to cities and riverside populations that use its tributaries as a source of food, income, and leisure.