Investigating the Sustainability of Vegetation Change Trends Using Remote Sensing (Case Study: Northern River Basin of Afghanistan)

Drought is a phenomenon that occurs at different times unpredictably with different intensity and has severe effects on human society and ecosystems. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) and PERSIANN Dynamic Infrared Rain Rate (PDIR Now) sensors were applied to examine the drought effects on vegetation in Northern River Basin of Afghanistan from 2001 to 2020. Therefore, MODIS data include Enhanced Vegetation Index (EVI), Vegetation Condition Index (VCI) with a time period of 16 days and a spatial resolution of 250 meters, Land Surface Temperature (LST) with spatial resolution of 1 km and period of 8 days, and monthly precipitation data with a resolution of (4*4) km. The relationship between drought and vegetation in spring was investigated using time series analysis, regression analysis and calculation of anomalies.  The results showed that the average vegetation coverage in the whole statistical period was 45.21%. In this study, vegetation area in 2001, 2008 and 2011 have reached the lowest rate (9.9%, 9.9% and 19.3%), respectively. According to VCI, 83.5%, 81.39% and 74.9% of the basin in these years are under drought conditions, respectively. Rainfall data confirm that these years have had the lowest rainfall 96.7, 133 and 117 mm, respectively. The years 2003, 2009 and 2010 with the highest vegetation in this season were recorded mainly due to the lower LST and higher rainfall then their average period. The correlation between EVI and LST is (r=-0.87; p<0.05), EVI and Precipitation (r=0.60; p<0.05). However, in Northern River Basin of Afghanistan, LST and rainfall must be considered together to determine the relationship between drought and vegetation dynamics properly.