Estimativa do fator L da Equação Universal da Perda de Solo em escala regional – aplicação para o Estado de São Paulo

To integrate studies in the Earth System Science context, erosion models were applied only in local scale have been adapted to regional scales such as the Universal Equation for Soil Loss (USLE). Among the parameters required by USLE to estimate soil loss rates the slope length (L) is the main factor favored by advances in the acquisition of Remote Sensing data, especially topographical, and the development of Geographic Information Systems (GIS) and it responsible for satisfactory local-regional adaptation of the model. In this context, the aim of this study was to obtain the L factor map for the Sao Paulo State using the equation of Desmet and Govers (1996), a methodology that employs the concepts of flow direction and accumulate area. Therefore, it was used ArcGIS software and elevation data from TOPODATA project that have a spatial resolution of 30 m. The results showed that the lowest values occurred in interfluves (hilltops) and larger towards the bottom of the valley where there is significant distances from the turning point and flow convergence, and steep slopes (same behavior as the accumulative area). Thus, the higher the L value, the greater the speed and the concentration of runoff, which allows us to infer that these are the areas more conducive to the occurrence of erosion.