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Université de Sherbrooke (1995)

Analyse de la désertification au Sahel par télédétection : cas de la zone d’Ansongo au Mali

Goïta, Kalifa

Titre : Analyse de la désertification au Sahel par télédétection : cas de la zone d’Ansongo au Mali.

Auteur : Goïta, Kalifa

Université de soutenance : Université de Sherbrooke,

Grade : M.Sc. 1995.

Résumé
The study, based on Landsat 1, 2 and 5 data, outlines the changes that have occurred in the north-Sahelian sector of Ansongo, in the north-east of Mali. The images corrected for radiometric and atmospheric effects were used for calculating the surface albedo and the vegetation index following the normalized difference method (NDVI). The analysis of the variations of these two parameters in conjunction with the land cover shows a continuous and significant trend towards desertification in the southern part of the study area between 1973 and 1986, with an increase in the albedo in the order of 15% and a decrease of the NDVI in the order of 17%. In the northern area, the trend is less pronounced and the increase in the albedo is in the order of 8%. A classification of the land cover into eight classes for each date permits to explain the degradation processes involved. The results show an important anthropic pressure on the vegetation cover due to population migrations towards the south following prolonged and successive periods of drought to the north. This analysis thus highlights the important spatial variability of land surface temporal evolution in the Sahel, which must be taken into account in a mesoscale regionalization study.

Mots Clés : Environmental science, Applied sciences, Remote sensing, Health and environmental sciences, Geography, Social sciences

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Page publiée le 21 mars 2010, mise à jour le 31 janvier 2018