Evaluation of Desertification Intensity Using Soil Indices

Soil characteristics are the most powerful factors in desertification phenomenon. The purpose of this study was investigating soil characteristics as indices for evaluating desertification intensity. The most important indicators of the soil that affect desertification were selected in the present study. Soil samples were taken from Segzi desert vicinity located in the east of Isfahan city with surface area of 112،167 ha. Soil indices such as Soil texture، soil gypsum percentage، the content of HCO3-1، electrical conductivity (EC)، pH، the percentage of the organic matter، the content of the soil sodium، chloral and sodium absorption ratio (SAR) were selected. All of these indices were calculated on the thirty four soil samples. After ensuring of the normality of the samples by Klomogrov-Smirnov test، the mentioned indices were imported into GIS for delineating soil characteristics maps. To delineate distribution maps of each soil indice، inverse distance weighting and ordinary and discrete Kriging methods were applied، and appropriate method was selected. Each layer was scored based on MEDALUS model، and the final characteristic maps were then generated using soil geometric mean indices. Results showed that the affected areas of the average، severe and very severe classes of desertification were calculated about 66000، 45650 and 517 ha، respectively. The results also revealed that the indices of the organic matter، soil gypsum percentage، electrical conductivity and SAR were the most influential indicators، which affected desertification in the study area.