Desertification is one of the most important challenges of this century. This problem can be seen not only in arid and semi arid areas, but in some areas of dry semi-humid. At present desertification as a problem, is involved many countries, including developing countries. Desertification process is related to natural factors and incorrect human performances. The purpose of this study is to assess the current status of desertification in south and east vast plains of Segzi in Isfahan province. Study area covers 112167 ha, and south boundary of region is limited to Zayanderud River. In present study, Medalus model is used for assessment of the desertification process. For this purpose, the six major criteria including: status of vegetation, climate, soil, ground water, erosion (water and wind) and the management and policies are used. Each criterion involves numerous indices; so that the plant covers Criterion is including four indexes: percentage of plant cover, range condition trend, conservation against erosion and resistance against drought. The climate Criterion is including three indexes: precipitation, potential of evapotrairation and aridity index, the soil Criterion is including eleven indexes: soil pH, electrical conductivity (EC), percentage of organic matter, percentage of soil gypsum, percentage of soil chloral, content of soil sodium, soil texture, content of soil HCO3, sodium absorption ratio (SAR), content of calcium and Mg and percentage of soil saturation moisture, ground water Criterion is including seven indexes: content of chloral, content of calcium, content of HCO3, ground water pH, ground water electrical conductivity (EC), sodium absorption ratio (SAR) and TDS and erosion Criterion is including two indexes: PSIAC Key Words : Desertification, MEDALUS model, Criteria, Index, Isfahan Segzi plain
