Impactos antrópicos na hidrologia e no potencial de geração hidroelétrica no Alto Rio Grande - MG

Abstract

Brazil is extremely dependent on its water resources, especially the energy sector, which hydropower is responsible for producing about 70% of all electric energy in the country. Thus, changes in the hydrological regime due to changes in land-use and climate can compromise the capacity of electric energy generation, as well as reduce the water availability. In this context, the objective of this study was to evaluate the hydrological impacts due to changes in land-use and climate in the headwater region of the Alto Rio Grande using the hydrological model SWAT, as well as to simulate the impacts on the potential of electric energy generation in Camargos, Itutinga and Funil hydropower plants. The results showed that SWAT was able to adequately reproduce the hydrological processes of the analyzed outlets. Simulations of hydrological impacts due to changes in land-use through five trend scenarios have indicated that the availability of the water resources in the region may change. The scenarios S1 and S 2, which represents the deforestation of the native forest into pastures, indicated an increase in the runoff, with consequent increase in the surface runoff due to the reduction of the infiltration and soil water holding capacities, which can lead to a reduction of groundwater recharge capacity. On the other hand, reforestation scenarios (S 3 and S 4) indicated a reduction in the runoff and surface runoff due to better infiltration conditions and greater soil retention capacity. The conversion of pasture into agriculture (S 5) indicated an increase in the runoff and surface runoff. The results related to the hydrological impacts of climate change indicate a reduction in the average monthly flow rate during the analyzed period, for both models (Eta-HadGEM2-ES and Eta-MIROC5) and Representative Concentration Pathways (RCP 4.5 and RCP 8.5), with the most critical projections based on the Eta-HadGEM2-ES model. The results indicate that Camargos, Itutinga and Funil hydropower plants could suffer serious consequences in terms of potential electric energy generation, failing to operate in 28%, 69% and 50% of the time, respectively, during the period between 2071 and 2099, because the minimum generation capacity would not be reached.