Impactos das mudanças climáticas e do uso da terra nas perdas de solo da bacia hidrográfica do rio Piauitinga-SE

Abstract

Climate change and changes in the use and coverage of land, caused by human activities, have been changing the soil loss in the Brazilians watershed. Therefore, this paper estimated soil loss by extensive erosion in the watershed of the Piauitinga-SE river and assessed the possible effects of climate change and land use and land cover over the loss of soils in the basin. For this, we used the Universal Soil Loss Equation of (USLE) associated with GIS and remote sensing techniques. Historical series were used (between 15 and 68 years) daily rainfall and data on climate projections coming from the Global Climate Model (GCM), generated by the Community Climate System Model (CCSM) to the fourth assessment report of the Intergovernmental Panel on Climate Change ( IPCC). In the physiographic characteristics of the watershed, were used soil map, hydrographic network, slope information and images of high spatial resolution of the RapidEye sensor to year 2013. With this data, two estimates of soil loss were realized. The first estimate was considered two scenarios for the watershed: Scenario 1 (C1) with physiographic and usage conditions and current land cover; Scenario 2 (C2) with changes in land use and land cover, considering the preserved the Permanent Preservation Areas (PPAs), as Law No. 12,651/2012. In the second estimate it was considered four climate scenarios of rainfall: Current Scenario, Scenario optimistic (Low B1), Scenario Medium (Medium A1B) and scenario Pessimistic (High A2), and, for them, was only considered natural factors of erosion in the basin. In the first estimate, the two scenarios (C1 and C2) of use and assessed land cover presented most of the basin area with erosion between classes Very Low (0-5 ton-1.ha-1.year), Low ( 5-10 ton-1.ha-1.year) and moderate (10-50 ton-1.ha-1.year). Considering the scenario 2, there was a reduction in soil loss values, especially in the PPAs, proving the importance of maintaining these areas preserved for conservation of soil and water in the basin. As for the second estimate, it was observed that, when compared to the Current Scenario, the climate projections scenarios (Optimistic B1, Medium A1B and Pessimistic A2) caused reduction of rainfall erosivity and soil loss in the basin river Piauitinga - SE