Deforestation Estimates in Avhrr/noaa and Tm/landsat Images for a Region in Central Brazil

This paper presents a comparison of tropical deforestation estimates in AVHRR/NOAA and TM/Landsat images for a region in Central Brazil where large clearings in the forest prevail. A TM scene of 02/Sept/89 in the scale of 1:250,000 was visually interpreted to produce a map with four classes: natural forests, deforested areas, natural savannahs, and rivers. The AVHRR image of 17/Sept/89 with full 1.1 km resolution was, digitally degraded to 2km resolution and classified to show forested and deforested areas. Comparison between deforested areas detected in the two data bases was done in a Geographical Information System for 54 grid cells of 10xl0 minutes. AVHRR channel 3 (3.7um band) provided the best results. A linear relation was found with a Determination Coefficient of 0.93, higher than previously reported in the literature for other AVHRR channels. The methodology developed is recommended for early location and assessment of new tropical deforestation.