Abstract
This study assessed the impact of climate change on monthly streamflow in the Verde River Basin, located in the Grande River Basin headwater. For this purpose, the SWAT and VIC hydrological models were used to simulate the monthly streamflow under RCP4.5 and RCP8.5 scenarios, obtained by Regional Climate Models Eta-HadGEM2-ES, Eta-CanESM2 and Eta-MIROC5 in the baseline period (1961-2005) and three time-slice (2011-2040, 2041-2070, and 2071-2099) inputs. At the end of the century, the Eta-HadGEM2-ES showed larger decrease of precipitation in both radiative scenarios, with an annual reduction of 17.4 (RCP4.5) and 32.3% (RCP8.5), while the Eta-CanESM2 indicated major warming, with an annual increase of 4.7 and 10.2°C under RCP4.5 and RCP8.5, respectively. As well as precipitation changes, the Eta-HadGEM2-ES also showed greater impacts on streamflow under RCP4.5 for the first time-slice (2011-2040), with an annual decrease of 58.0% for both hydrological models, and for the RCP8.5 scenario by the end the century (2071-2099), with an annual reduction of 54.0 (VIC model) and 56.8% (SWAT model). Regarding monthly streamflow, the Eta-HadGEM2-ES and Eta-CanESM2 inputs indicated decrease under the RCP8.5 scenario by the end the century, varying from 7.2 to 66.3 % (VIC model) and 37.0 to 64.7% (SWAT model). In general, Eta-MIROC5 presented the opposite in terms of direction in the simulations with both hydrological models at the end of the century. Combined effects of climate models, hydrological model structures and scenarios of climate change should be considered in assessments of uncertainties of climate change impacts.
Highlights
The objective of this research was to compare climate change responses in the Verde River Basin, southeast Brazil, using two hydrological models: Variable Infiltration Capacity (VIC) that divides the basin into regular grid cells, and Soil and Water Assessment Tool (SWAT) that disaggregate a basin into subbasins and hydrological response units based on land use, topography and soil classes
The coupled simulations are referred to as Eta-HadGEM2-ES-ES, Eta-CanESM2, and EtaMIROC5, when the Eta model is driven by HadGEM2-ES, CanESM2, and MIROC5, respectively
SWAT and VIC models were not calibrated using similar methods, but showed similar performance during calibration according to the statistical precision indices
Summary
Climate change and human activity influence hydrological processes, causing critical impacts on both the dynamics of ecosystems and society, and affect urban water supply systems, irrigated agriculture, and hydropower production (Viola et al, 2014; Oliveira et al, 2017; Byun et al, 2019).The upper Rio Grande Basin, located in southern Minas Gerais state, has great relevance in water availability and hydropower production, contributing to the Furnas hydropower plant reservoir (Pinto et al, 2019; Oliveira et al, 2017). In South America, some studies (Chou et al, 2014; Ribeiro Neto et al, 2016; Oliveira et al, 2017) evaluated projections Eta driven by HadGEM2 and MIROC5, for two scenarios (RCP4.5 and RCP8 .5). These studies indicated an increase in temperature and a reduction in precipitation, mainly in the central and southeastern regions of Brazil, a fact that may indicate a considerable reduction in streamflow and in the potential for energy generation, throughout the 21st century. It was found in these studies that Eta-HadGEM2-ES is more sensitivity in these changes than the Eta-MIROC5
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