LAND-USE CHANGE IMPACTS ON THE HYDROLOGY OF THE UPPER GRANDE RIVER BASIN, BRAZIL

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: S-1 and S-2 - conversion of forest into pasture of 20 and 50%, respectively; S-3 and S-4 - conversion of pasture into forest of 20 and 50%, respectively. The results have showed that, in general, the deforestation scenarios (S-1 and S-2) presented an increase in total runoff and peak flow and a decrease in the baseflow and evapotranspiration, whereas the reforestation scenarios (S-3 and S-4) 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.