ASSESSMENT OF VULNERABILITY TO DESERTIFICATION USING THE MULTI-CRITERIA ANALYSIS BY THE WEIGHTED SUM METHOD

Despite the fact that desertification affects 41% of lands, there is only a few comprehensive methods to assess desertification. This study was conducted in order to assess the vulnerability to desertification caused mainly by anthropogenic actions associated with arid climate. It describes a global method of spot assessment of vulnerability to desertification. The first step of this method is to categorize and delimit bio-geographical areas that are homogenous from climatic, edaphic and floristic point of view in Morocco. Then, the land uses of these homogeneous areas are mapped into seven main classes and from that, the vulnerability to desertification of each area is assessed by the multi-criteria analysis by weighted sum method. This analysis is based on biophysical and anthropogenic factors such as temperature, precipitation, terrain, soil type, forest and matorral cover, cropland, stocking rate, and population density. The results point out that the forest and matorral cover has increased these last years, even though the forests have regressed. On another side, the weighted sum method have showed better results by indicating the degree of vulnerability of each homogeneous areas. Thus, the highest vulnerable area is Agricultural plains of Gharb. This method can be adapted, and then reused to assessed vulnerability in other countries or regions of the world affected by desertification.