Uso recomendado da terra: uma análise a partir do diagnóstico ambiental e da vulnerabilidade natural à perda de solos na sub-região hidrográfica do Itacaiúnas (PA)

Abstract

Studies covering several environmental variables have become increasingly essential. Through integrated analysis, sustainable models are developed using methodologies that aim at environmental limits. The objective of this research is to propose a land use recommendation for the Itacaiúnas hydrographic sub-region, specifically, addressing different environmental variables, through physical environmental diagnosis, investigating environmental dynamics related to natural vulnerability to soil loss and analyzing the interrelationships of lithology, geomorphology, pedology, climate and vegetation variables. The study area is located in the South and Southeast of Pará, with an area of 41,300 km2, being the contribution of the Itacaiúnas, Parauapebas, Vermelho, Cateté, Tapirapé and Sororó rivers. For the development of the research, it was necessary to divide it into two parts. Firstly, a physical environmental diagnosis was carried out, through the analysis of the environmental variables available for the elaboration of the natural vulnerability to soil loss, based on what was proposed by Crepani et al. (2001). Then, a recommended land use model was created, based on the methodology proposed by Brito (2001), adding the variables of land use and occupation, areas of permanent preservation and natural fragility of soils. The main results found are, firstly, the environmental diagnosis, which may include the predominant lithology in the area, called amphibolite; geomorphology is defined with relief subdivision taxons; at a higher level, the Neoproterozoic cratons, Neoproterozoic mobile belts and Quaternary sedimentary deposits; the geomorphological regions of residual plateaus of the southern Amazon, depressions of the southern Amazon and the depression of the Araguaia River; the geomorphological units of the Carajás Hills, fluvial plains and terraces, the Bacajá depression, the middle Xingu depression and the middle and lower Araguaia depression; and, finally, those modeled with a predominance of the convex top dissection class. Referring to vegetation/land use, the classes with the highest incidence are pasture and rainforest. Regarding the climate, the presence in the Amazon region can be highlighted, inserted in the so-called “Amazonian winter” (TAVARES et al., 2018). In terms of climate classification systems established by Köppen and Geiger (1928) and Alvares et al. (2013), these demonstrate the occurrence of three climatic types: humid or super-humid tropical climate, humid or sub-humid tropical climate and tropical climate, with dry winter. The predominant pedological class identified is called dystrophic red-yellow Ultisol. The natural vulnerability to soil loss made it possible to verify the absence of the stable class and the predominance of vulnerability is moderately stable or vulnerable. Regarding the recommended land use, six classes were defined with their own characteristics, which are environmental recovery area, restricted use area, high restriction area, medium restriction area, low restriction area and permitted use area; most of the study area is found as an area of low restriction. In summary, it is concluded that the methodology used in the present research was successful in the elaboration of an environmental diagnosis of the physical aspects and in the creation of the recommended land use.