Mudança no uso de solo e no aporte de sedimentos na bacia hidrográfica do submédio rio São Francisco.

Abstract

The mapping and assessment of risk of erosion is important for planning of natural resource management tool, allowing strategies to be implemented more sustainable long-term management. This work aimed to calibrate and validate the SWAT model (Soil and Water Assessment Tool) for the simulation of runoff and sediment delivery in the Lower Basin Watershed of Rio São Francisco (BHSRSF). For this, georeferenced maps of current land use, soil units and digital elevation model were used in addition to meteorological and hydrological data of the study area. In the study time series of monthly streamflow data from three gauged stations and daily meteorological data from nine meteorological stations distributed in the study area were used. The result of simulations for different soil enabled the identification of areas that present the greatest potential hydro, pedological and associated erosion of the relief, as well as all the interaction of soil-plant-atmosphere system interface. The SWAT model was calibrated and validated successfully using the flow values appropriately for fluviometric season Juazeiro, having obtained values of EMP of -3.2% and 0.8% for the calibration and validation periods , respectively. The largest value for the R factor was found for the station Backwater (5315 MJ mm ha-1 h-1) defined as moderate to strong erosive potential. The change of pasture cover for bare soil observed in scenario 3 indicated the impact of changes in surface characteristics in view the climatic conditions of semi-arid regions, the components of runoff and sediment delivery were the most sensitive to changes, with alterations on their values in current conditions of coverage.