In the semiarid northeast, the increase in the area of deforestation and non-reclaimed 'Caatinga' sites already degraded weaken its soils and hydrological balance. This study aimed to map the alteration in the vegetation cover along the Espinharas River sub-basin area during the period 2000-2010. The image data collected from the thematic mapper sensor of the satellite Landsat-5 were processed with the aid of computational systems Spring. In order to evaluate the vegetation cover, the normalized difference vegetation index was used. Sixty five percent of the area presented high level of anthropogenic disturbance, sparse vegetation and exposed soils. The difference in image, whose values were analysed taking into account the values of the average distribution of gray levels in the image (µ) standard deviation (σ) according to the thresholds [0, μ - σ], [μ - σ, μ + σ] e [μ + σ, 254], related to the following classifications: deforestation/reduction of vegetation cover, no change and areas of regeneration/vegetation growth. The results showed that 80% of the area remains unchanged, reduction of vegetation cover occurred in 12.6% of the area due to the practice of clear cutting of vegetation in order to obtain firewood for domestic or commercial use and also area preparation for agriculture purposes; some increment was observed in 7.4% of the area possibly due to cultivation of irrigated and non-irrigated pastures in alluvial soils.
semiarid northeast; 'Caatinga'; normalized difference vegetation index; georeferenced information processing system
