Abstract
ABSTRACT Land-use changes are considered one of the most important factors that affect the water resources. The objective of this study was to investigate the potential impacts of land-use changes on the hydrological behavior of the Upper Grande River Basin, southern Minas Gerais state, Brazil, based on different land-use scenarios using the SWAT model. For this purpose, daily streamflow records from the Macaia gauge station were calibrated and validated under the current land-use. To assess land-use change impacts four land-use scenarios were developed following official environmental planning reports: S1 and S2 - conversion of forest into pasture of 20 and 50%, respectively; S3 and S4 - conversion of pasture into forest of 20 and 50%, respectively. The results have showed that, in general, the deforestation scenarios (S1 and S2) presented an increase in total runoff and peak flow and a decrease in the baseflow and evapotranspiration, whereas the reforestation scenarios (S3 and S4) have showed the opposite. The results showed that the land-use changes can generate positive impacts, such as reduction of surface runoff and increase in the baseflow, as well as negative ones, like the increase of soil erosion and flood risks.
Highlights
Brazil is strongly dependent of the surface water resources for economy and, very susceptible to the weather variability and changes in the hydrological regime
The country relies in its water resources to generate electric energy, where almost 78% of all energy is produced by hydropower plants (EPE, 2016; Oliveira et al, 2017)
The model performance statistics showed that Soil and Water Assessment Tool (SWAT) was able to adequately predict the daily streamflow in GRB-M, presenting a Nash-Sutcliffe Efficiency (NSE) of 0.72 and percent bias (PBIAS) of 2% for the calibration period and 0.63 and 10%, respectively, for the validation period
Summary
Brazil is strongly dependent of the surface water resources for economy and, very susceptible to the weather variability and changes in the hydrological regime. Streamflow yields in this region is extremely important, since it directly supplies three hydropower plants (Camargos, Itutinga and Funil) and play an important role in hydrology regulating other downstream reservoirs, highlighting Furnas hydropower plant (Oliveira et al, 2017; Viola et al, 2013). Land-use changes have been considered one of the most important factors that affect water budget in watersheds (da Silva et al, 2018). It is well-established that land-use changes may alter the water balance components, which can cause both positive and negative impacts (dos Santos et al, 2018; Bruijnzeel, 1990)
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