DEFORESTATION DETECTION IN THE AMAZON WITH AN AVHRR-BASED SYSTEM

This paper presents initial tests of a novel and relatively simple met hodology for near real-time operational detection of deforestation in Amazonia. Channel 3 (3 . 7 mu m) full resolution (1 . 1 km) and geomet rically corrected images of the Advanced Very High Resolution Radiomet er (AVHRR) on-board the NOAA-series satellites covering the same regio n on different dates are digitally compared. Differences in forest cov er between pairs of images are automatically selected as potential def orestation sites. In the tests, three AVHRR images (September 1989 and 1990; July 1990) were compared with 30 m high-resolution Landsat Them atic Mapper (TM) data using a geographical information system (GIS) in tegrated to the image processing. The percentages of correct location of newly deforested sites for September 1989-1990 and September 1990-J uly 1990 comparisons were, respectively: 49 . 1 and 56 . 5 per cent fo r about 200 deforestation sites of assorted sizes, and 82 and 90 per c ent for sites larger than 3 . 1 km(2).