Integrated study of the erosive process in a experimental watershed located at Cunha (São Paulo State – Brazil)

Abstract

The goal of this paper was to organize a database about the parameters of the erosive process for a watershed located at the city of Cunha (eastern portion of the São Paulo State) and to elaborate the maps about Natural Potential for Erosion (NPE) and Soil Loss Expectative (SLE). The Universal Soil Loss Equation (USLE) is the applied mathematical model, and GIS technology (Idrisi software) was used. Two land cover scenarios were used: one corresponding to the actual land cover (natural forest), and one hypothetic scenario corresponding to a uniform pasture land cover. Throughout analysis of the USLE factors and PNE map it was observed that the watershed is highly vulnerable to erosion process. For SLE elaborated considering the natural vegetation, the important role that such land-cover type plays in order to control the erosive process is noted. The SLE map elaborated for the pasture showed that the soil loss would be highly and dangerously increased if none conservationist practice were applied and/or the soil was misused. The estimated annual values of soil loss are: 5.1 t.ha-1 for the natural vegetation, and 28,280.0 t.ha-1 for pasture.