Current World Environment

The sensitivity map to desertification of Chehel-chai basin (North of Iran) has been elaborated by the crossing of fives criteria including climate, water erosion, soil, vegetation, and management, which have the main impact on the evolutionary process of desertification. The methodology is resulted from the desertification model of MEDALUS, which use qualitative index to define the land sensitive area to desertification. According to the factorial scaling technique, score-ranging from 1(good condition) to 2(deteriorated condition) is assigned to each indicator. Each index was assessed based on selected indicators, which resulted in qualitative mapping of each index based on geometric average of the indicators. Thematic databases, with a 1:50000 scale resolution, were integrated and elaborated in GIS software based on arc view3.2, Ilwis3.1 and ArcGIS9.3. The obtained results indicate that 39.39% of Chehel-chai basin is highly sensitive to desertification, 2.13 % has moderate sensitivity, only 2.43% has low sensitivity and 56.05% is non-sensitive. Studying the mean weight of numerical value, it is distinguished that the intensity of desertification for the total area is 1.32 which is classified as fragile (2).