Document Type : Original Article
Authors
1
Ph.D Student, Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2
Department of Environment, College of Basic Sciences, Hamedan Branch, Islamic Azad University, Hamedan, Iran.
3
Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran. Department of Water Engineering, Collage of Agriculture, Isfahan University of Technology, Isfahan,
4
Department of Technical & Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
Abstract
The main aim of the present study was to investigate the effects of drought on vegetation cover. An available climatic data series (2001-2017) was analyzed to detect wet and dry years by SPI. Also, a long data series of MODIS data was analyzed by remote sensing data, and the NDVI maps have been produced. Results of the present study show that there is a direct, significant correlation (R2 = 0.364) between SPI and the NDVI. In addition, during the study period, the years 2008 and 2016 were selected as dry and wet years, respectively, based on SPI values. The values of the NDVI in the wet year (2016) were significantly higher than the values in the dry year (2008) at a 99% confidence level. The results further show that elevation classes in dry conditions do not play an important role on the value of the NDVI; however, in wet years the results were different, and by increasing the range of elevation, the value of the NDVI is also increased. Generally, the results of the present study show that MODIS data in a mountainous area can be a key tool for detecting the effects of intensive droughts on natural vegetation cover.
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