Potenciais do meio físico no alto curso da bacia do Rio das Velhas: perspectivas das transições para diferentes usos

Abstract

The Alto Rio das Velhas watershed is one of the most important right bank tributaries belonging to the São Francisco River Basin, both in terms of water volume and pollution-related impacts. This makes the region a stage for study and research, since the area is one of the most critical in the state of Minas Gerais in relation to the pressures of use and exploitation of its resources. From the point of view of management, land use and public policies, the understanding of this whole scenario can favor better management of the environment, considering current use and environmental conservation. For the monitoring, management and conservation of different activities and resources, the use of geotechnologies has become a viable alternative for a better understanding and management of space and favoring the elaboration of plans. The research is then justified by the scenario of land use and occupation conflicts in the Alto Velhas Region and also by the importance of an integrated analysis of the landscape considering the discussion of topics such as land use and occupation, physical potential, preservation and environmental impact. Thus, this study aimed to identify the relationship/interaction between the Conservative Use Potential (PUC) and the dynamics of land use and land cover and to identify and analyze the conflicts of use arising from this relationship/interaction in the basin region. The PUC method reconciles the interpretation of the physical environment with cartographic purposes, contemplating in this work the spatial analysis of the Alto Rio das Velhas watershed, considering the potential for agricultural use, water recharge and resistance to erosive processes. The PUC is expressed through the algebra of maps and zonal assessments from the weighting of values given to slope classes, soils and lithology. The results show an overview of the main temporal changes in land use and land cover in the Alto Rio das Velhas Basin for the years 1985, 2000, 2010 and 2019 and the main problems and consequences for the environmental quality of the basin taking into account the land use and land cover. Among the anthropic uses, the ones that expanded most were urban infrastructure (increase of 46.57%), mining (increase of 36.62%) and planted forest (increase of 299.30%). It is noteworthy that due to the intense urbanization process and the types of use and occupation in the basin, it presents environmental pressures in the preservation areas and in the springs that impact both the soil and its water availability. Based on the integrated analysis between the PUC and land use and cover, it was possible to point out areas of environmental fragility, in addition to discussing the method as a territorial management tool and its potential to guide public policies. Among the results observed, it can be highlighted that the PUC Very Low and Low areas together occupy 63.65% of the total area of the basin. Relief features vary from strongly undulating to mountainous/craggy with steep slopes. The predominant soils, “Cambissolos” and “Neossolos” (Brazilian soil classification system’s class), are influenced by the source material. Mineral exploration, urban infrastructure and the presence of gallery forests in the drainage headwaters are concentrated in these areas, where fragility for agricultural activities is observed. The regions with Medium, High and Very High PUC together occupy 36.35% of the total study area. The declivity does not exceed 20%, the relief features vary from flat to moderately undulating. The predominant soils are “Cambissolos” and “Latossolos”, but small patches of “Argissolos” (Brazilian soil classification system’s class) are also found. The relief, lithology and soil characteristics provide greater stability and, therefore, a higher PUC favors greater resistance to erosive processes. These are areas with greater propensity for agricultural use, in addition to the feasibility of destination for the preservation of natural resources. The basin in question has low potential for use in the upper reaches, in addition to environmental and exploration pressures in the area, taking into account mineral exploration and sources of water capitation and recharge areas. Therefore, these areas deserve attention and are a challenge in the management of the territory.