Impacto das mudanças da cobertura e uso da terra nos processos hidrológicos da bacia hidrográfica do Rio Pojuca, Bahia, Brasil

Abstract

When societies undertake large-scale transformations in the hydrographic basins they occupy, they pecisively impact hydrological processes, causing changes in the quality and quantity of water available to meet multiple demands. The present study aims to analyze the influence of changes in land cover and land use on water and sediment production in the Pojuca river watershed, in the state of Bahia. The evolution of land cover and land use in this watershed was evaluated for the period between 1985 and 2020, and four scenarios were constructed: (i) Recovery of Permanent Preservation Area - APP, (ii) Total Deforestation, (iii) Total Reforestation, and (iv) Trend - 2055. The model was calibrated using two different methods: (i) Single Site Calibration - SSC and (ii) Simultaneous Multi-site Calibration - SMSC. Most of the performance statistical indices confirmed the ability of the model calibrated with both methods to adequately simulate flows and sediments at the basin outlet. Regarding flow results at an intermediate point in the basin, the model calibrated with the SMSC method showed superior performance to the SSC method. Simulation of the different scenarios indicated that total reforestation of the basin resulted in growth in mean flows (15%), minimum flows (11%), base flow (18%), and recharge to the deep aquifer (17%). The trend scenario for 2055 indicated a 25% increase in surface runoff. The basin's behavior regarding flow and sediment production showed little variability among scenarios.