Análise da vulnerabilidade ambiental como subsídio à gestão de recursos hídricos: estudo de caso da bacia hidrográfica do Ribeirão do Lage/MG

Abstract

The management of water resources in a basin requires knowledge of the conflicts over these. In this sense, the analysis of environmental vulnerability in river basins is an important tool in strategic environmental planning. This study has as main objective to carry out the analysis of emerging environmental vulnerability associated with the water availability of the Ribeirão do Lage-MG Hydrographic Basin (BHRL), of the UPGRH of the Rio Caratinga- MG in order to assist decision making in the management of water resources in this basin from the multicriteria analysis using the geographic information system - GIS. For the elaboration of the environmental vulnerability map of the basin, the methodology which uses a nominal hierarchy of fragility, represented by classes, according to its degree of vulnerability for the components: Land Use and Occupation, Declivity, Rain Erosivity, Soil Classes and Classes of Relief Dissection, assigning values, so that the higher the class value, the greater the degree of vulnerability. In the second phase of the study, the management of water resources in the basin was analyzed by assessing data on grants and insignificant uses granted by the competent environmental agency. The values of Q7.10 of the mouth of each segment of the hydrography of the basin with granted grants were calculated, obtained from the flow regionalization procedure using the method of Superficial Defluvios in the State of Minas Gerais and from the flows found it was calculated the conflict indexes for the use of water in the management of water resources (Icg) of BHRL. The results indicate that BHRL's soil use and occupation conditions, present a strong presence of coffee and livestock and along with the processes of morphogenesis and pedogenesis, with the high declivity and dissection of the relief are the main factors of environmental fragility of this basin, providing greater surface runoff, erosive processes and sediment dragging to the Ribeirão do Lage bed, which can lead to silting and also changes in the quality and quantity of available water. However, the category of soil classes becomes a favorable environmental potential due to the predominance of Oxisols, soils are more resistant to these erosions. Spatially, it is noted that the river segments with granted flow higher than the minimum reference flow and the other segments are found in areas with a strong emerging environmental vulnerability index (4). This indicates the need for elaboration of actions with the Basin Plan, strategically improving the management of local water resources, which will enable the development of agriculture with more conservationist agricultural practices and actions to recover degraded areas. Thus contributing to a greater articulation between the basin committees and the public power, as well as the population directly involved so that there is negotiation and construction of a management environment, of intermediation between public, private and civil society, creating resource management resources consistent with local territorial management.