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-arid and dry sub-humid areas resulting from various factors، including climatic variations and human activities. It has been recognized as a major economic، social، and environmental problem in many countries of the world. The MEDALUS methodology is a practical approach to 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 SEGZI plain (Eastern Isfahan) based on the MEDALUS methodology. At first step، seven criteria including climate، soil، vegetation cover، ground water، water erosion، wind erosion and policy and management were recognized according to the local condition. Each criterion 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 were assigned and desertification weighting was finally extracted. The weight of each factor and the weight of desertification status was calculated by geometric mean. Ultimately، desertification status was classified in four levels including low، moderate، severe and high severe. 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 as severe and 63% involved high severe class. Climate، policy and management are the most important factors have led to desertification process in this region.