Assessment and mapping the total risk of desertification using FAO and UNEP modified method (Case study: Gharachay watershed)

A temporary model to assess desertification and providing the map of land susceptibility to the reducing processes of land efficiency was proffered by FAO and UNEP. The results of regional implementation of the FAO and UNEP method in Gharachay watershed are presented in this article. In this method, five major processes of land degradation were evaluated with two aspects including "current status" and "inherent risk". For any of these aspects, the maps of low, moderate, severe, and very severe desertification were separated and the area of each class was calculated. Then, the maps of main processes affecting desertification were integrated together and two maps including "current status and inherent risk" were provided. Afterward, the maps of livestock pressure and human population were prepared. In order to obtain the total risk of desertification, the four mentioned maps were integrated and finally the risk of desertification classes were calculated. In view of the current desertification status in the studied region, the following results were obtained: The highest vegetation decline (76%) was observed in the east, south, and center of the region. The highest percentage of water and wind erosion (45.2%, 57.9%) was obtained in the south and east respectively; the highest soil salinization (34.7%) was observed in the east. In addition, the highest loss of groundwater resources was observed in the center and east of the region. The highest livestock pressure (58.3%) was recorded in the center of region; however, population pressure had little impact on environmental degradation. The area of each category, including low, moderate, severe, and very severe, was calculated to be 39.4, 27.9, 25.1, and 7.3 percent, respectively. Overall, according to the obtained results, the natural and human factors, particularly livestock pressure, were effective to create these conditions.