Análise da vulnerabilidade à erosão como subsídio ao planejamento territorial da região fisiográfica do Médio São Francisco

Abstract

Human interventions in the Middle São Francisco watershed are carried out on a large scale because it is a region of high socioeconomic importance and has multiple uses, with significant energy, agricultural and agroindustrial potential, in which the erosion processes in the land and the silting up of the land intensify. water bodies. Therefore, this work aimed to map and analyze the areas vulnerable to erosion processes, in the physiographic region of the middle São Francisco, located in Bahia. The multicriteria analysis methodology was used with the support of geotechnologies and geographic information system (GIS) to process data that constitute the explanatory variables or criteria. The analysis process was carried out in two stages, the first consisting of making maps of the slope, geology, pedology, rainfall intensity and land use and occupation criteria, assigning weights (on a scale of 0 to 1) to carry out the normalization of their respective thematic classes, based on the assumptions of Fuzzy logic. This was followed by weighting the relative importance between the criteria, based on knowledge extracted from the literature and on the opinion of specialists who work with this topic. In the second stage, the aggregation of multiple criteria was carried out, through the Weighted Linear Combination, which generated the summary letter of vulnerability to erosion. The results show that the very low and very high vulnerability classes had lower coverage, with 4.9% and 0.5% respectively. The low vulnerability class had the greatest coverage with 49%, followed by the medium vulnerability class with 24.9% and the high vulnerability class distributed in 20.8% of the area. The identity territories that showed the highest level of vulnerability were those of Rio Grande, Rio Corrente and Irecê, with intensive agricultural and livestock activities being found in these regions. The territory that presented less vulnerability to erosion was the Sertão do São Francisco. It is recommended to carry out territorial planning and development of public policies taking into account the critical areas found in each territory of the study area.