Assessing Sensitivity to Desertification in Mashhad County of Iran Using the Fuzzy Overlay Method

Document Type : Research and Full Length Article

Author

Assistant professor faculty of geography and invironmental science hakim sabzevari university, sabzevar, iran

Abstract

In this research, we used six MODIS remote sensing products to evaluate vulnerability to desertification in Mashhad County of Iran in the year 2020. The Enhanced Vegetation Index (EVI), Vegetation Condition Index (VCI), Salinity Index (SI), Synthetized Drought Index (SDI), Temperature Condition Index (TCI), and precipitation for the month of May of 2020 as the month when vegetation growth reaches its maximum were considered. Data layers were standardized using the Fuzzy Transform Function and scaled using the Analytical Hierarchy Process (AHP). Regarding TCI, VCI, and SDI the greatest proportion of the area fell under the no to mild drought category indicating a lower risk of desertification. However, the Synthetized Desertification Index (SDI) is mainly distributed around the moderate and mild classes (~39%). The results of the EVI index also indicated that most of the area has a suitable vegetation density and low risk of desertification. As for the SI index, ~98% happened under the low salinity risk. Based on the results of the Analytical Hierarchy Process (AHP) method, precipitation (0.25), VCI (0.25), EVI (0.18), and SDI (0.13) obtained the greatest weights. The final vulnerability score ranged between 0.29 and 0.63. The results showed that the greatest parts of the area belong to the moderate risk (~68%) and high risk (30.1) classes of desertification. The highest values were obtained in the east and south-eastern parts of the area with the lowest level of vegetation density, and high-temperature indices. The comparison between the results and the ground truth data indicated high compatibility (kappa value of >0.70). Naturally, the elevations received the lowest values (~0.29) showing an increasing gradient towards the middle plain. Mashhad City as the major population center of the area is located in the low-risk category therefore, desertification doesn’t seem to be threatening the city at the moment.

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Articles in Press, Accepted Manuscript
Available Online from 26 February 2022
  • Receive Date: 11 October 2021
  • Revise Date: 19 February 2022
  • Accept Date: 26 February 2022
  • First Publish Date: 26 February 2022