Impacts of climate change on the evaporation and availability of water in small reservoirs in the Brazilian savannah

The Cerrado (Brazilian savannah) is one of the few places in the world that has the potential to increase crop production to meet the projected food demand for 2050. However, for agriculture to be sustainable in this region, irrigation must be efficient. This depends on the water stored in small reservoirs, which play an important role in supporting the local economy. The increase in temperature and net radiation predicted by global climate models may increase the evaporation and reduce the availability of water in these small reservoirs. This work assesses the projected impact of climate change on small reservoir evaporation and water availability in the Brazilian savannah using data from the Eta-HadGEM2-ES and Eta-MIROC5 regional climate models under representative concentration pathways (RCP) 4.5 and 8.5. Evaporation increases of 7.3% (1.09 mm/year−1) and 18.4% (2.74 mm/year−1) are projected in RCP 4.5 and RCP 8.5, respectively, by the year 2100. The water stored in reservoirs is projected to decrease in the future, resulting in higher risks of failure in water supply, especially from the smaller reservoirs. Overall, evaporation increases are expected to reduce the availability of water in small reservoirs during the dry season by 5.5% in RCP 4.5 and 10.4% in RCP 8.5.