Etude des latérites par télédétection. Cartographie thématique de Banankoro et Dagadamou : corrélation des données géochimiques, comparaison multitemporelle et classification des images SPOT au Sud-Mali

A detailed geochemical mapping of Iateritic superficial formations in South Mali is compared with SPOT satellite multispectral images. The two main landscape features concem the distribution of vegetation caver and the distinction between silty clay soils in the valleys and ferricrete exposed on the plateaus. The density of vegetation on ferricrete is related to their kaolinite content. Plateaus are surrounded by a halo of high reflectance corresponding to the bottom slope detrital accumulation of quartz and heavy minerals. Some results of thematic mapping based on SPOT images over the lateritic area of BANANKORO in South Mali are described. Several methods of supervised classification have been used. The best results are given after class definition on bidimensional histograms corresponding to SPOT XS channels or first factors of PCA Preliminary structural mapping is achieved wtth the help of KIRSCH operator for edge and line enhancements.