FROM VULNERABILITY MAPPING TO EROSIVE PROCESSES RESULTING FROM MULTICRITERIAL METHODS: A STUDY ON THE ENVIRONMENTAL CONDITIONS OF THE HYDROGENIC BASIN OF LARANJA DOCE DAM IN MATINOPOLIS, SAO PAULO STATE, BRAZIL

Abstract

This paper shows the application of a methodology to identifies and map vulnerable erosion areas thought the study of the environmental conditions of Represa Laranja Doce basin located in the municipality of Martinopolis (Sao Paulo state, Brazil), where there are various types of land use and occupation. The morphogenesis and pedogenesis balance was used as a theoretical reference to consider vulnerability of erosive processes using available information on geology, slope, geomorphology, soil typology and land use. This mapping was performed by a geographic system information, through multi-criteria methods, one of them being the Weighted Average Inference and the other one being the decision support of Analytic Hierarchy Process (AHP), and validated by the contrast with satellite images. The results show the environmental conditions of the basin, according to its degree of vulnerability of erosive processes, where about 70% of its area is considered to be stable. Besides, the carried out analyses qualify the methodologyand it shows that such condition occurs due to the characteristics of the relief units and the land use forms. Therefore, a condition which arises from relevant human's actions in the Geographic Space.