Caracterização espacial e morfométrica de bacias hidrográficas em uma área prioritária para conservação na região norte do estado de Minas Gerais

Abstract

Priority Areas for Conservation are a public policy instrument used to support decision making in the planning and implementation of actions aimed at the protection and sustainable use of natural resources. Due to the crucial role of water resources for maintaining the ecosystem balance and for socioeconomic development, watershed have been adopted as units of study for conservationist interventions. For this reason, the characterization of watershed is relevant to elucidate the hydrological behavior, which in turn, provides essential information to support territorial management. In this context, the present study aimed to carry out the spatial and morphometric characterization of the River Congonhas (BHC) and Rio Macaúbas (BHM) watershed, belonging to a portion of priority conservation area, inserted in the Espinhaço geology, north region of the State of Minas Gerais. The studied basins are regionally important for their considerable water supply and for being rainwater recharge areas. The environmental characterization consisted of mapping the hydrography, slope, hypsometry and soil distribution of the watershed. For morphometric characterization, indexes were used with the aid of geotechnologies, which are related to dimensional, drainage and relief patterns. BHC and BHM extend over 1,332.69 km² and 1,047.37 km², and have a drainage network length of 2,328.63 km and 2,409.42 km, respectively. BHC has approximately 2,146 springs and BHM 2,449. Both have an elongated shape, a characteristic that favors the drainage process and, therefore, have low susceptibility to the occurrence of floods, under normal rainfall conditions. The altimetric amplitude values are 647 m and 777 m and maximum height of 1,398 m and 1,381 m, respectively. As to declivity, in BHC there is a predominance of smooth to wavy relief (3% to 20%) and in the BHM area there is a predominance of wavy relief (8% to 20%). The soil mapping showed that red latosol and cambisol haplicum are the most common types in BHC. In the BHM, the red latosol predominates, with a considerable band of rocky outcrop in the east-south portion. The results also showed that BHRM has the highest values of drainage density, frequency of rivers and texture ratio, indicating that it is naturally more subject to erosion processes, thus suggesting the sustainable planning of land use and occupation and special attention to maintaining natural vegetation cover. Therefore, the data generated in this work support the need to expand the mechanisms of protection and conservation of the natural resources of the studied watershed, especially the springs and their recharge areas, which are essential to guarantee the water supply in the region.