Change Detection, Mineralogy, Desertification Mapping in East and Northeast of Ahvaz City, SW Iran Using Combination of Remote Sensing Methods, GIS And ESAs Model

Desertification is the reduction of ecologic and biologic on the earth surface, which might happen naturally or unnaturally (human). In this research, the TM and ETM images were used to study changes occurred in sand dunes during last 11 years and for determining the type of clay minerals. For evaluation of changes, maximum likelihood image classification and LMM, methods are carried out. According to results of change detection, area of active sand dunes has decreases from 9335 Hectare to 7330 Hectare. For determination of mineral type and their distribution map, XRD method was used in conjunction with band rationing of 2/5 and 6/4. It shows that for determination of clay minerals, ratio 2/5 and separation of Kaolinit from Illite, ratio 6/4 is very useful. Using desertification (ESAs methods) and Geographical Information System (GIS), desertification map of study area is prepared. For ESAs method four criteria; vegetation cover, soil, climate and management are used. Parameters for each criterion evaluated according to their effects on desertification process and a weight was given ranging from one to two. Weight one (1) is the best weight and weight 2 is the worst one. The results indicated that 56% of the area belongs to critical class of c2-type and 26% in c3-type of desertification class and the rest goes to other less affected category. Key word: Image processing • LMM • Mineralogy • Sand dune • XRD • Desertification • ESAs