The increasing trend of natural resources degradation threatens the human life over the world. Desertification as a sign of land degradation affects many developing and developed countries. Over 250 million people are directly affected by desertification in the world. In addition, some one billion people in over 100 countries are at risk. These people include many of the world's poorest, most marginalized, and politically weak citizens. Desertification has long been recognized as a major economic, social, and environmental problem of concern to many countries in all regions of the world. According to the UNCCD definition, “Desertification” is land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities. According to this definition, natural and anthropogenic processes have main roles in desertification severity and this phenomena is often produced by a multiplicity of interacting environmental and socio-economic causes. The MEDALUS methodology is a practical approach to assess the present status of desertification and evaluating of desertification risk. In this study, have been developed a regional model for desertification assessment and mapping in SEGZI plain ( Eastern Isfahan ) based on MEDALUS methodology. At first step, main factors and indicators affecting on desertification process were identified. According to the local condition, seven factors include: climate, soil, vegetation cover, ground water, water erosion, wind erosion and policy and management were recognized. Each factor included several indicators accounting as factor quality determination. These indicators quantified based on their influences on desertification process. For each indicator a score ranging from 100 to 200 have been assigned. and desertification weighting was extracting. The weight of each factor and the weight of desertification status calculated by geometric mean. Ultimately, desertification status was Key words: Desrtification Assessment, MEDALUS, Geographical information system (GIS), SEGZI Plain, Desertification Mapping.
