Hazard Assessment of Desertification as a Result of Soil and Water Recourse Degradation in Kashan Region, Iran

Abstract

Desertification in arid, semi-arid and dry sub-humid regions is a global environmental problem. Considering the<br />increasing importance of desertification and its complexity, the necessity of giving attention to desertification criteria and<br />indices is essential. Models and methods such as MEDALUS, UNEP-FAO, and others have been proposed on local and<br />national scales. In this research, IMDPA was selected from among different existing methods, and desertification intensity<br />was evaluated on the basis of two criteria, soil and water, and 13 indices: soil depth, electrical conductivity of soil, texture,<br />gravel percentage, drainage, sodium absorption ratio, type of geologic formation, slope, groundwater table fluctuation,<br />electrical conductivity of water, color concentration, water crisis index, and water shortage for livestock and wildlife.<br />Each criterion was assessed based on the selected indices which resulted in the qualitative mapping of each criterion based<br />on the geometric average of the indices. Finally, a sensitive map of the region was extracted using the geometric average<br />of all criteria. Thematic databases with a 1:50000 scale resolution were integrated and elaborated in a GIS based on<br />ILWIS and arcGIS. Analysis of desertification criteria in the Kashan region showed that, among the studied criteria, water<br />criterion is a major problem in the study area. It has a geometric average of 3.59 which shows very high class, while soil<br />criterion with a weighted average of 2.12 stands in the medium class of desertification. The results also showed that<br />groundwater decrease and water crisis index with a quantitative value of 3.72 classified in a very high class of degradation<br />and depth with quantitative value of 1.20 classified in a low class of desertification were the most and least effective<br />factors, respectively, among the studied indices on land degradation.<br /><br />