Análise geoambiental da bacia hidrográfica do Ribeirão Borá: Sacramento/Conquista (MG)

Abstract

This research aimed to make a geoenvironmental analysis in the watershed of Ribeirão Borá, seeking to establish categories through the integration of natural variables. To this end, we applied the Theory of Geosystems which, among other purposes, seeks the conservation, rational space s use and sustainable development. The watershed is located in the region ( mesorregião ) of Triângulo Mineiro and Alto Paranaíba (MG), and it drained some land parts in the counties of Sacramento and Conquista, and it occupied an area of 357.81 km². We used cartographic documents by IBGE, GEOMINAS, EMBRAPA and CPRM; images of the Satellite ETM+/Landsat 5; socioeconomic data; bibliographic searches and field surveys. The work methodology followed the Libault s proposal (1971), which defines four levels of approach, namely: compilation, correlation, semantic and normative. The geoprocessing techniques were applied with the use of various softwares. The Formation Serra Geral main geological basement of the watershed (61%) associated with the semi-humid tropical climate leads to the formation of soils with the predominance of the class Oxisols, stands out Ustox (60% of the area) that, in general, has good physical structure for agricultural use, requiring only a few corrections chemicals, such as the use of lime. This framework interacts with an embossment predominant of Topo Plano (54%), without big ripples, that also facilitates agricultural activities and contributes to the maintenance of water resources in the subsoil. The land use and vegetation cover, between 2002 and 2009, revealed that, respectively, 70 and 72% of land in the watershed were occupied predominantly by human activities (grazing and agriculture). Moreover, we observed that 95% of the watershed s land has a high potential for economic use. However, we checked that part of agricultural activities also occupy areas of higher slopes (20-45%), this is not indicated, because the environmental legislation required that such areas should be preserved or designated to the legal reserve, in addition to being unfit for any use, according to the classification of land in the use capacity's system. Some suggestions were planning to adopt conservation practices with the intention to contribute to maximizing the potential of the watershed.