Zoneamento ambiental de bacias hidrográficas: estudo demonstrativo na Unidade de Planejamento e Gestão dos Recursos Hídricos Afluentes Mineiros do Baixo Paranaíba

Abstract

The exploitation of natural resources, intensified in the second half of the twentieth century, brought to the public debate the importance of environmental conservation, in which this issue was reversed in laws that aim the balance between economic growth and the preservation of nature. Thus, environmental instruments have been developed in several countries, such as environmental zoning, which stands out as a territory managing tool. In Brazil, although the instrument was defined by Law 6,938, of August 31, 1981, the regulation occurred only by Decree 4,297, of July 10, 2002. Therefore, this thesis aims to propose a methodological procedure for environmental zoning for watersheds based on the integration of physical-geographic and environmental variables, some of which are especially related to water resources. The area selected for application is the Water Resources Planning and Management Unit from Low Paranaíba River (UPGRH PN3), located in Minas Gerais State, Brazil. Theoretical and conceptual references include the principles of environmental zoning and its contribution to decision making in Brazil, the geographical categories of landscape and territory and watersheds as water resource planning and management units. As a basis for the research, some environmental zoning methodologies and the main geographic analysis operations in Geographic Information System (GIS) were also briefly described. To obtain the results, the research initially contemplated the diagnosis of the physical-geographic and environmental components (geological characteristics, aspects of the relief, soil classes, climatic conditions, land coverage and use, in addition to the availability of surface waters, conflicts water use and the quality of surface water). Then, these components were used to obtain the natural vulnerability to soil loss and quali-quantitative vulnerability of surface waters. Subsequently, conflicts between land use and the above-mentioned vulnerabilities were determined, as well as the conflict between land use and legally protected areas. These procedures determined two zones, which were called zone of conservation or recuperative interventions and zone of consolidated occupations and/or productive activities. Both were subdivided into areas (sub-zones) to identify spaces for preservation or recovery with different levels of urgency, in the case of the zone of conservation or recuperative interventions, in addition to portions with varied restrictions that were able to direct suggestions for environmental management in the zone of consolidated occupations and/or productive activities. From the results, it is understood that this environmental zoning can be a useful tool for planning and management of the study area, especially if integrated with other environmental policy instruments. Finally, we expect that the ideas regarding this work may be used in the UPGRH PN3 Water Resources Master Plan or that the methodological procedure is applied in similar territorial units.