Evaluation desertification by medalus model in the khozestan zone.

Arid and semi- Arid region is %80 of area Iran territory and third it susceptible to desertification. Now, desertification as a phenomenon dominant in arid and semi- arid region, threats life habitants this area and increase multiple hectar in area desertes every year. So survey states current desertification, Telloff the most important efficacious factors in creation and extension it, assessment process desertification and detect areas sensitive, is necessary for prevention in extension it. Purpose of this study is severance process main desertification and assessment survey states also mapping desertification and present a form predictable and communicative of states current the desertification in the khozestan region applying MEDALUS method. The criterions; climate, soil, vegetation cover and management by policy with tow watery and windy erosion criterion was assess. Any criterion has several index that unitage its efficacy in desertification have weight between 1 to 2 that is explanatory least and most efficacy in desertification, Respectively. Then map for any criterion produce of numeral average indicator and at the end desertification map of numeral average criterions. criterions and respective indicators score in work envelope units. According to results desertification present status at locale, severe %28.7 and very severe %71.3 area so sensitivity class is at totale of zone critical (C2,C3) and %71.3 of region is C3 critical class.Cities situate at partes eastern and southeast state was current status desertification severe by sensitivity class C2 and in other area current status desertification and sensitivity class is very severe with C3 class. Results show that most effective for criterion in desertification is including; management by policy, vegetable cover, windy erosion, and climate by score average 176.4, 166.8,164.75 and 162.13 effecte very severe by most effective indicator average of criterion. indicator effect ;at management by Policy at pasture using the destruction of pasture with average 186.4 has most effecte, maintenance activity by score 181.66,index of percent of vegetable cover at criterion vegetable cover by score169.125., index of frequency erosivity wind has most score equal 187.9 that is more effect at desertification, in climate evaporation by average 182.56. soil by average 145.2 has severe effecte study index of soil show that percent organic material, rapport of sodium absorbent(SAR), percent of gravel and conduction electric tidy has score 169.6,164.35,159.4 and 148.7 that are more effecte at desertification in criterion. watery erosion effecte with average 132.5 is average. average quantity value severity desertification for total region at six touchstone is studies DS=156/66 so for region total present status and sensitivity class to desertification is estimat at very severe by critical (C3) class and this area is subject efficacy factors natural as high evaporation, superabundance winds by threshold velocity and human factors such as want existence suitable management and Policy similar intensive graze, use unsuitable of land and incorrect methods at agriculture key Word: desertification, khozestan zone, medalus, touchstone,water erosion, wind erosion