Impacts of land-use changes on the hydrology of the Grande River Basin headwaters, Southeastern Brazil

Abstract

Land-use changes affect soil water balance. The Upper Grande River Basin (UGRB) headwaters have undergone intense modifications in land use. This study was conducted to simulate, using the LASH model, the impacts on the hydrological regime in the UGRB with five land-use trends: S1 and S2 – reforestation with eucalyptus covering 20 % and 50 %, respectively, from the current grassland area; S3 – reforestation with eucalyptus covering 100 % of the current grassland area only in the sub-basins where this trend is predominant; S4 and S5 deforestation of 30 % and 70 % of the forest remnants in the Mantiqueira Range region for the cultivation of grasslands, respectively. Results demonstrate that runoff would be reduced due to the land-use changes by 51.65 mm yr−1, 110.29 mm yr−1 and 59.48 mm yr−1 for scenarios S1, S2 and S3, respectively. However, scenarios S4 and S5 could increase streamflow by 57.63 mm year−1 and 156.78 mm year−1, respectively. This indicates that land-use changes might make the basin more prone to flooding and other hazards associated with increased runoff.