Abstract
The sensitivity map to desertification of Chehel-chai basin (North of Iran) has been elaborated by the crossing of fives criteria including climate, water erosion, soil, vegetation, and management, which have the main impact on the evolutionary process of desertification. The methodology is resulted from the desertification model of MEDALUS, which use qualitative index to define the land sensitive area to desertification. According to the factorial scaling technique, score-ranging from 1(good condition) to 2(deteriorated condition) is assigned to each indicator. Each index was assessed based on selected indicators, which resulted in qualitative mapping of each index based on geometric average of the indicators. Thematic databases, with a 1:50000 scale resolution, were integrated and elaborated in GIS software based on arc view3.2, Ilwis3.1 and ArcGIS9.3. The obtained results indicate that 39.39% of Chehel-chai basin is highly sensitive to desertification, 2.13 % has moderate sensitivity, only 2.43% has low sensitivity and 56.05% is non-sensitive. Studying the mean weight of numerical value, it is distinguished that the intensity of desertification for the total area is 1.32 which is classified as fragile (2).
Highlights
Defined as the change of fertile and productive lands into non-productive desert areas, desertification remains as a major environmental concern in most arid, semiarid, and sub-humid areas of the world (Dregne, 1977; United Nations Convention to Combat Desertification (UNCCD), 1994; Herrmann & Hutchinson, 2005)
The United Nations Convention to Combat Desertification (UNCCD), which is the only internationally legally organization, offers strategies to combat desertification and mitigate the effects of drought through national action programs that incorporate long-term strategies supported by international cooperation and partnership arrangements
The geometric average and qualitative classes of indicators of each index have been summarized in Tables 9 and[10]
Summary
Defined as the change of fertile and productive lands into non-productive desert areas, desertification remains as a major environmental concern in most arid, semiarid, and sub-humid areas of the world (Dregne, 1977; UNCCD, 1994; Herrmann & Hutchinson, 2005). (Kassas, 1977; Mainguet, 1994; Blum, 1998; Krishan et al, 2009). Among these factors, unsustainable human activities, such as urbanization, overgrazing, over-cultivation, poorly drained irrigation systems, deforestation, etc. Are currently considered as the most important factors accelerating the process of desertification (BarberoSierra et al, 2013; Bo et al, 2013). Unsustainable human activities, such as urbanization, overgrazing, over-cultivation, poorly drained irrigation systems, deforestation, etc. In addition to these direct effects, human activities may indirectly contribute to desertification, for example through affecting environmental factors such as climate (Kassas, 1977; Khosravi, 2004). Several models have been developed and a large number of studies have been carried
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