assessment of present status of desertification and modifying the medalus model in segzi plain of isfahan

according to the unccd definition, “desertification” is land degradation in arid, semi-aridand dry sub-humid areas resulting from various factors, including climatic variations andhuman activities. it has been recognized as a major economic, social, and environmentalproblem in many countries of the world. the medalus methodology is a practical approachto assess the present status of desertification and evaluate the desertification risk. in this study,a regional model has been developed to desertification assessment and mapping in the segziplain (eastern isfahan) based on the medalus methodology. at first step, seven criteriaincluding climate, soil, vegetation cover, ground water, water erosion, wind erosion and policyand management were recognized according to the local condition. each criterion includedseveral indicators accounting as factor quality determination. these indicators quantified basedon their influences on desertification process. for each indicator a score ranging from 100 to200 were assigned and desertification weighting was finally extracted. the weight of eachfactor and the weight of desertification status was calculated by geometric mean. ultimately,desertification status was classified in four levels including low, moderate, severe and highsevere. at last the maps of these results was produced by geographical information system.results showed that 2% of the study area was classified as moderate class, 35% classified assevere and 63% involved high severe class. climate, policy and management are the mostimportant factors have led to desertification process in this region.