Impact of climate change in the flow regimes of the Upper and Middle Amazon River

The impacts on global water resources may be more intense due to climate change, making access to water more difficult and, consequently, maintaining life. In the Amazon, the effect may be even worse, as it is one of the region's most vulnerable to these changes. Thus, the objective is to analyze future variations in the volumes and duration curves of the flow of the Amazon River to verify the hydrological response to climate changes. The daily flows observed were from the database of the National Water Agency of Brazil. Future flow data was generated for the Representative Concentration Pathways (RCPs) 6.0 and 8.5 scenarios of the Global hydrological model WaterGAP2 forced by the General Circulation Models MIROC5 and HadGEM2-ES, obtained from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) platform. The flow duration curves of the base periods were created from the last 20 years of observed data for each flow meter station, as well as the simulated base period curves (2000-2019), to compare with the curves of future scenarios (from 2020). For a more punctual analysis, decadal volumes were also analyzed. WaterGAP2 was efficient, presenting the classification "very good" for most stations analyzed according to the adopted statistical indicators. Most of the extreme flows were observed from 2080 to 2099. For WaterGAP2 (MIROC5), in most stations, volumes were below the expected decadal average for the century generally from 2020 to 2059. Increasing again after 2060 for WaterGAP2 (HadGEM2-ES) projections, the volumes are usually close or below the decadal average, with a decrease from 2060 (generally for RCP 8.5).