Ajuste no fator C da RUSLE e avaliação temporal da cobertura e perda de solo estimada na bacia hidrográfica de Palmares- Ribeirão do Saco/RJ

Abstract

The importance of studying soils in order to preserve its functions includes conservation efforts whose goal is to ensure preservation of natural resources for future generations. This study works with the scientific hypothesis that changes in vegetation cover in the watershed of Palmares-Ribeirão do Saco, Rio de Janeiro State, in the period of 2009-2015, favored the erosion reduction in this area. To verify this trend an estimate of soil losses was made with use of RUSLE (Revised Universal Soil Loss Equation) which allows generating information to build up management plans to secure agricultural production, and to preserve natural resources of the region. Thus, the objective was to develop a methodology for assessment of vegetation affected by seasonality and able to reduce erosion, based on the NDVI (Normalized Difference Vegetation Index) in order to reduce part of values overestimation associated to errors in the RUSLE model. As secondary objective, to compare estimates of erosion and natural erosion potential (NEP) in the period of 2009-2015 with those obtained in the period of 1986-2009, in order to verify environmental impacts in the watershed. The area studied was the watershed of Palmares-Ribeirão do Saco, located between the municipalities of Paty do Alferes and Miguel Pereira in the state of Rio de Janeiro. Even without the adoption of conservation practices by some of the region farmers, the general aspect of data provided by RUSLE and the NEP in recent years has shown that soil losses are tending to decrease, mainly due to the low recorded rainfall indexes, implying at low erosivity values.