Analysing environmental changes in the neighbourhood of mines using compressed change vector analysis: case study of Carajas Mountains, Brazil

Remote sensing image databases and geographic information system have the potential to act as accurate tools for environmental monitoring. Carajas Mountains are an important mineral deposit in Brazil and as environmental laws protect a great portion of this region, they have been at the core of conflicts involving human and nature interests. The biggest mining project in Brazil is active in this region (Carajas project) and this analysis aims at identifying the environmental impact caused directly or indirectly by this activity using state-of-the-art methods. This study collects information of land-use and land-coverage from an area larger than 111,000 km² including five municipalities, aiming at observing the landscape intervention from a large-scale perspective as a counterpoint to other studies which are focused on a particular region, such as watersheds. Therefore, employing the resultant products of the multispectral approach called Compressed change vector analysis analyses both the environmental changes in each studied municipality of the Carajas Mountains and the environmental counterpart of the company that runs the mining activity. The results show that in general the vegetative coverage was replaced by pasture lands, which in turn were replaced by urban occupations. The comparison with official statistics indicates good accuracy of the present study in the estimation of vegetative cover, although the authors claim that the official methodology can produce inaccurate percentages, probably due to the shortcoming of classification of degraded forests and forest in regeneration process. The presence of environmentally protected areas has prevented the increase of deforestation in the mountains, in which the observed change rates were at least 15% lower than non-protected regions.