Assessment of Desertification Risk in Semi-Arid Agh-Band Region, Golestan Province, Iran

ABSTRACT: Nowadays, risk has a widespread and multi-dimensional meaning which depends on safety, economic, social and environmental issues. The best definition for the risk may be the correlation between parameter (element) and hazard word. This research was conducted in the semi-arid region of Agh-Band, Golestan province, Iran, with onearea of about 3062.5 km2. The main purpose of the research was assessment of desertification risk. To assess the desertification hazard, the Iranian 9-criteria model of IMDPA and geomorphology faces were used. Map of working units (geomorphology faces) was prepared based on geological and land-use maps, satellite images, and field surveys. The differences between areas of map classes were compared using Chi-square test. To prepare the risk map, first elements at hazard were determined and classified. Then, by using the hazard intensity map and degree of vulnerability each element, the desertification risk classeswere obtained via general equation of risk(R= H.E.V)at four classes. From landuseand topography maps, area of agricultural lands and number of springs, number of residential sites, length of roads were determined and then were transformedbased on these information the map of element at hazard was prepared. To determine vulnerability classes of components, an expert coefficient was used. The results showed that the numerical value of desertification intensity for the entire study area was 2.03 which according to the current classification of IMDPA model, is considered as moderate desertification class (II). Also, for each pixel the risk value was calculated and classified in four classes, namely low, moderate, high and very high, based on turning points of the cumulative frequency curve.About30.03% percent of the study area was classified as high and very high (III and IV) classes of risk.