Ambientes, uso e ocupação do solo e zoneamento estratégico para as sub-bacias dos rios Jacupiranga e Pariquera-Açu, Vale do Ribeira, SP

Abstract

In this research were mapped soils, geomorphology and geo-environments of sub-basins of river Jacupiranga and river Pariquera- Açu. It was identified nine units of mapping pedological: Cambisol Haplics phase strong emphasis wavy; Haplic Cambisol moderate relief phase; Haplic Gleissol relief phase plan to gentle wavy; Haplic Gleissol relief phase to smooth wavy corrugated; Latosol red-yellow wavy relief phase; Latosol Yellow Strong relief phase wavy; Argisol Red Yellow; Argiluvic Chernossolo and Litolic Neossol. From the geomorphological units defined, returned to the map of Geo-environments, which joined the characteristics of topography, soils, geology and vegetation cover in the region studied. The samples of soils collected in the field were characterized in terms chemical and geotechnical. The chemical analysis showed that most soils have very low fertility and high levels of aluminum, which affect conventional farming practices. There has been geotechnical characterization through tests of size, the limits of Atterberg and the method of chips (MCT methodology). The soil had a larger majority of its size clay and silt, with variations on the behaviour Laterite. The MCT methodology proved to be useful in comparison with the methodologies of classification USCS and TRB, which are frequently used. Through multicriteria analysis were selected environment’s factors for further assessment of the susceptibility to erosion of the study area. The factors were: the average annual rainfall, the map of slope, map of land use and soil and vegetation covering the year 2006. The analysis showed that 48% of the area is in the class of high and very high susceptibility to erosion due to soil characteristics and the high slope. Was evaluated the socio-economic activity through the analysis of satellite images between the years 1984, 1990 and 2006. The analyses between changes of use showed the strong pressure manmade observed between 1984 and 1990, where 24% of the cover was removed. Between 1990 and 2006, it was observed that the removal of vegetation cover was 5%, which demonstrates the stabilization trend that may be associated with soil and geomorphological features of the region. Despite this framework, the pastures have had strong tendency to increase of its area covered, that progress is generally on the old areas of agriculture. This fact, cause the abandonment of areas and encourages the exposure and frequent occurrence of erosive soil by the lack of vegetation cover. For the zoning of areas of strategic development, 28,473 ha have been selected as the most appropriate from the multicriteria analysis. It was used all the information developed over this search. The selected areas are conducive to use in agro-forestry systems and livestock, provided that established the correct management. This zoning, coupled with public incentives for local development, has great potential to change the quality of life of the municipalities involved.