Document Type : علمی - پژوهشی


1 Department of Geography, Faculty of Literature and Human Sciences, Lorestan University

2 lorestan university


In the coming years, drought is one of the potential threats to low rainfall countries, especially Iran. Iran has always faced big and small droughts. The geographical location and natural conditions of the country are such that severe and weak droughts have occurred in it. Evaluating the effects of drought on vegetation is very important. In order to reduce damages and consequences caused by drought, drought monitoring using remote sensing method is considered in most countries because of its advantages. In this study, in order to reveal the effects of precipitation on vegetation in Iran, the precipitation data of 143 synoptic meteorological stations of the country were used to calculate the monthly average of the Standard Precipitation Index (SPI) in the period 2000-2021. Then, using visible infrared images (VIIRS) as a weekly average in the period of 2013-2021 (April 1st to the end of July every year) obtained from the Suomi NPP sensor, the drought condition of the vegetation was investigated. Based on the obtained results, it can be said that the vegetation cover in 2015 and 2021 was more affected by drought than the other investigated years. The most severe vegetation drought occurred in 2021. In 2016, 2019 and 2020, vegetation was in more favorable conditions. The correlation of SPI with NDVI, VCI, TCI and VHI was calculated as 0.1906, 0.038, 0.016 and 0.002 respectively.