Simulação hidrológica e avaliação dos índices de seca meteorológica e hidrológica utilizando projeções climáticas na bacia hidrográfica do Rio Verde

Abstract

The impacts caused by climate change can affect the water cycle causing damage to the economy, society and the environment. This research proposal has four main objectives: To analyze the performance of the hydrological models Lavras Simulation of Hydrology (LASH), Distributed Hydrological Model (MHD-INPE), Variable Infiltration Capacity (VIC) in the Rio Verde-BHRV watershed; Analyze the behavior and frequency of meteorological drought and its impacts using the climate projections of the RCP4.5 and RCP8.5 scenarios and the ensemble of the three global models (HadGEM2-ES, MIROC5 and CanESM2) regionalized by the Eta model in the BHRV; and Analyze the behavior and frequency of hydrological drought from the flows simulated by the VIC and SWAT models in the BHRV, using the climate projections of the RCPs. BHRV is located in the south of the state of Minas Gerais, inserted in the Serra da Mantiqueira, one of the most important headwater hydrographic regions in Brazil. The performance analysis of the three hydrological models (LASH, MHD and VIC) were compared using statistical indices. The SPI and SPEI indices were used for meteorological droughts and the SSFI index for hydrological droughts, based on flows simulated by the SWAT and VIC hydrological models. The calibration and validation results showed a good performance of the LASH and MHD-INPE models in simulating the BHRV flow in the daily time step. The performance analysis of the hydrological models showed that LASH and MHD-INPE better simulated the average discharges, in the dry and rainy seasons, when compared to the simulation results with the VIC. These results justify the indication of the use of LASH and MHD-INPE in studies related to the prediction of flow in the dry and rainy season in the region. In this research, it was possible to diagnose the possible impacts of drought in the region using the drought indices standardized precipitation index (SPI), standardized precipitation and evapotranspiration index (SPEI) and standardized flow index (SSFI), based on climate projections of the RCP4.5 and RCP8.5 scenarios. In the present climate, a strong correlation was found between meteorological (SPI) and hydrological (SSFI) droughts, which indicates a rapid response of the basin to meteorological droughts. In the future climate (2005-2099), the SPI presented similar simulated drought frequency distributions for RCP4.5 and RCP8.5. The SPEI provided different results between the scenarios, especially for RCP8.5, in which a serious risk in the future of occurrence of megadrought due to the decrease in precipitation and increase in temperature was evidenced. In the future climate, in turn, SSFI simulated extreme droughts for RCP4.5 and, for RCP8.5, moderate droughts followed by severe droughts. These results can be used by managers in decision-making to minimize the impacts of severe drought that could affect the environment, agribusiness and affect the level of reservoirs and hydroelectric power generation in the region.