Monitoring the magnitude of land-cover change around the southern limits of the Sahara

Studies of land-cover change using satellite remote sensing are often const rained to depict land-cover conversions only, with the equally important mo difications undetected or misrepresented, resulting in significant error. D esert fluctuations within the Sahel were examined using an approach that in dicated the magnitude of land-cover changes. This showed that the conventio nal post-classification comparison method of change detection appeared to u nderestimate the area of land-cover change and, where a change was detected , typically overestimate its magnitude. At the regional scale, the land-cov er changes detected were strongly related to rainfall variability This rela tionship did not, however, explain changes at a finer spatial scale and ind icated that dryland degradation, and its causes, may remain far from unders tood.