Towards operational systems of monitoring regional patterns of degradation in Sahelian Africa - a multisensor remote sensing approach

Presents preliminary results of two case studies focussing on Sahelian regions of the Niger inland delta (Mali, West Africa). The focus is set on the important preprocessing step of data homogenization for supporting reasonable comparative investigations of multitemporal and multisensor Earth observation data. The first study deals with the preprocessing of radiometric and atmospheric corrections applied to a series of LANDSAT-MSS data from the dry season of 1972, 1974 and 1982, covering the region of Lac Faguibine, at the northern fringe of the Niger inland delta. The accurate assessment of landcover change depends on the correction of different sensor radiometry. The second study deals with computer assisted photo interpretation. Image analysis of rasterized photographic data has some positive drawbacks compared with traditional visual photo interpretation. Results of detection and evaluation of quantitative indicators are more accurate and thus finer landcover change evaluation is made possible