Land cover and climate change effects on streamflow and sediment yield: a case study of Tapacura River basin, Brazil

This study assesses the impact of the land use and climate changes between 1967-2008 on the streamflow and sediment yield in Tapacura River basin (Brazil) using the Soil and Water Assessment Tool (SWAT) model. The model was calibrated and validated by comparing simulated mean monthly streamflow with observed long-term mean monthly streamflow. The obtained R-2 and Nash-Sutcliffe efficiency values to streamflow data were respectively 0.82 and 0.71 for 1967-1974, and 0.84 and 0.82 for 1995-2008. The results show that the land cover and climate change affected the basin hydrology, decreasing the streamflow and sediment yield (227.39mm and 18.21 t ha(-1) yr(-1) for 1967-1974 and 182.86mm and 7.67 t ha(-1) yr(-1) for 1995-2008). The process changes are arising mainly due to the land cover/use variability, but, mainly due to the decreasing in the rainfall rates during 1995-2008 when compared with the first period analysed, which in turn decreased the streamflow and sediments during the wet seasons and reduced the base flow during the dry seasons.