چکیده:
Desertification is recognized as a serious environmental threat in Iran because of its climatic-geomorphologic conditions. Desertification and land degradation in arid, semi-arid, and dry sub-humid regions, is a global environmental problem. Accurate assessment of the status and trend of desertification is instrumental in developing global strategies to prevent and reverse this problem. The goal of the present study was to discover and introduce criteria and quantitative indices and test modeling to monitor and assess desertification in the ecosystems of Iran. Past research
has shown that effective factors for desertification can be categorized into nine groups of criteria. For each criterion is typified by a group of indices. All indices have been adjusted to natural conditions in Iran and their qualification is based on expert knowledge and the range of natural occurrence. The Iranian model of desertification potential assessment (IMDPA) was used to evaluate desertification risk in the Farasman region in central Iran. The results show that, in spite of
common techniques, the proposed method has the best accuracy and produces precise results. The data were integrated over a regional geographic setting using a GIS, which facilitated data display and the development and exploration of data relationships, including manipulation and simulation testing. Results show that about 77% of the area fell into the moderate category, 15% fell into the low category, and the rest (8%) fell into the high category for desertification risk. It was found that the overall severity of land degradation and desertification in the study area has increased during the last two decades with highly and moderately degraded land accounting for 77% of the total area in 2010. The incorporation of natural and anthropogenic factors into the analysis provided a realistic assessment of the risk of desertification.
خلاصه ماشینی:
The complex nature of the effective factors of desertification and the lack of appropriate and regular cooperation between the responsible organizations and the model users has limited the preparation of a fully developed model for assessment of desertification, land degradation intensity, and early warning systems on the global, regional, national, and local scales.
The present study also devised a methodology for realistic assessment of the severity of desertification and to calculate land degradation hazards in the ecologically vulnerable area along the Farasman basin in central Iran.
1. 3 = score of drought period index Terrain mapping units (TMU) were determined based on a geomorphologic survey (geobiofacies) to implement a practical evaluation project for desertification assessment based on satellite images, aerial photography, land use, and erosion features.
In the second stage, reclamation projects and management design should be consideredIMDPAi = final score of desertification risk Q1 = score of weather criteria (climate, irrigation) Q2 = score of land criteria (soil, geology and geomorphology, erosion); Q3 = score of vegetation criteria (agriculture, vegetation) Q4 = score of human criteria (socio-economic, urban development, technology) The cluster criteria combination and symbol of indices are shown in Fig. 2.
ResultsDPAi = desertification potential assessment Q1 = score of weather criteria (climate, irrigation) Q2 = score of land criteria (soil, geology and geomorphology, erosion) Q3 = score of vegetation criteria (agriculture, vegetation) Q 4 = score of human criteria (socio-economic, urban development, technology) TMUs were determined based on geomorphology and erosion facies (geobiofacies); in each unit, to determine current conditions, all criteria and indices should be qualified.