Quantifying the climate change-driven impacts on the hydrology of a data-scarce watershed located in the Brazilian Tropical Savanna

Abstract

Tropical savannas are one of the most affected biomes worldwide by anthropogenic activities. The Cerrado biome, also referred to as the Brazilian Tropical Savanna, is one of the world's environmental hotspots due to its high biodiversity and endemism. Also, it is essential for water resources in South America and hydropower generation in Brazil. In this context, this study aimed to evaluate possible changes in water availability in the Cerrado due to the impacts of climate change throughout the 21st century under different emissions scenarios. The Soil and Water Assessment Tool (SWAT) was calibrated and validated in a watershed encompassing 51 237 km2. The regional climate models (RCMs) Eta-HadGEM-ES and Eta-MIROC5 under the representative concentration pathways (RCPs) 4.5 and 8.5 were used to simulate the streamflow changes in three time slices (2010–2040, 2041–2070, and 2071–2099). The streamflow can be reduced by up to 70%, being Eta/HadGEM2-ES RCM under RCP 8.5 projected the most severe impact. On average, the most significant runoff reductions occurred in the first and third time slice (−54.51%). Baseflow and evapotranspiration can reduce up to 55% and 23%, respectively, at the end of the century. In addition, the hydrological drought assessment stressed the higher frequency of severe drought events in the first time slice. Streamflow regularization can be an alternative to mitigate the impacts of climate change in the Brazilian Tropical Savanna throughout the 21st century.