Análise da fragilidade ambiental no Igarapé Caranã em Boa Vista, Roraima/RR

Abstract

The present work aims to analyse the degree of envinronmental fragility for mass movement, flooding and erosion, as well as to classify Igarapé do Caranã basin in geoenvironmental unities by studies of environmental elements and spatial occupation of the area. Adjustments were needed in the thematic maps of geology and the maps generated using integrated techniques of remote sensing and geographic information system (GIS). The selected method is separated in acquisition of bibliographic information, elaboration and organization of the database, elaboration of the environmental fragility maps for mass movement, erosion and flooding and geoenvironmental unities. Results show that regarding to mass movement fragility, the more representative environmental fragility class was low (78,67%) followed by very low class (18,10%). High and very high classes of environmental fragility (1,25%) located in the north-east quadrant of the study area, consist in parts of the land with an abrupt trend for landscape modeling. The environmental fragility class for flooding shows medium and high as predominant classes. Regarding to erosive vulnerability of Igarapé Canarã area, the predominant classes are very low and low (76%) followed by medium and high (20%) and very high (4%). Finally, grading the types of environmental fragility, the basin was classified in three classes of geoenvironmental unities where we have Environmental Fragility I (60%) which occupies almost all the basin and presents medium fragility to flooding. Unity Environmental Fragility II (39%) presents medium and high tendency to erosion and high tendency to flooding. The Unity of Environmental Fragility III (1% of study area) presents high fragility to mass movement, erosion and flooding.