Science et changements planétaires / Sécheresse


Development of the desertification sensitivity map of Algeria using remote sensing Volume 14, issue 3, JUILLET-AOÛT-SEPTEMBRE 2003


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Centre national des techniques spatiales BP 13, Arzew, 31200 Algérie <oussedikacnts.dz> *Suite à des problèmes d‘impression, nous publions à nouveau cet article initialement paru dans le numéro 2 de juin 2003

This paper presents a methodology used for building up the national desertification sensitivity map using remote sensing on the Algerian "steppe" zone which covers 14 million hectares. This study first consists in designing an appropriate methodology and testing it on the Djelfa area with a cartography at a scale desertification sensitivity scale of 1\200 000. The approach was based on the use of Landsat Thematic Mapper satellite data for the build‐up of the following thematic maps: land cover map from the TM4, TM3, and TM1 channels; morpho‐pedological map from the TM7, TM4, and TM2 channels; and sand cover map from the TM4, TM3, and TM1 channels. The desertification indicators taken into account in this study are the vegetation cover, the soil and the morphology. Each one of these indicators was classified with regard to its state and to its impact on desertification. The combination of each one of these indicators using a decision matrix and crossing significative parameters allows a level of sensitivity to desertification to be defined: desertified, very sensitive, sensitive, mildly sensitive and little or not sensitive. The study provides an overall vision of the Algerian steppic zone obtained through the national sensitivity map to desertification showing that more than half of the study area (53 %) falls into the very sensitive and sensitive desertification classes.