THE EVOLUTION OF EROSION FEATURES IN THE ESPRAIADO BASIN, SÃO PEDRO (SP) - DOI 10.5216/bgg.v35i2.37435

Abstract

In the 1980s it was estimated the occurrence of 3,000 gullies erosion in the state of São Paulo, and around 80% of crops fields had erosion processes that exceeded the natural recuperation limit. An annual loss reaching about 200 million tons of soil. Thus, the goal of this paper was to identify and evaluate the evolution of erosive features in the córrego Espraiado basin in the municipality of São Pedro (SP) between the years 1962 and 2006. For that, the erosion features were mapped in these scenarios (1962 and 2006) using orthophotos and field trips were carried out to check all the features and to calculate the volume of soil loss. The results shows a 76% of decrease between 1962 and 2006. The highest soil loss was identified in 1962, 4.410.000 m3 , in other words, 300% higher than 2006 scenario (1.428.000 m3 ). On both scenarios, the erosion features were located in high and middle levels of the basin. Therefore, using more accurate orthophotos it was possible to identify important changes in the spatial distribution of erosion features and in the total volume in of soil loss.

Key words: erosion features, São Pedro, GIS.