Assessing spatial variations of vegetative drought in Razavi-Khorasan province, northeast of Iran

Information concerning the spatial and temporal characteristics of vegetative drought is essential for decision-making in environmental and agricultural practices. The present study is a comprehensive Spatio-temporal analysis of vegetative drought over thirty years of observations.

The data obtained from NOAA/AVHRR (National Oceanic and Atmospheric Administration/ Advanced Very High-Resolution Radiometer) to reveal the vegetative drought patterns across Khorasan-e-Razavi province, northeast of Iran from 1990 to 2019. Three satellite-based drought indices including the Vegetation Condition Index (VCI), Temperature Condition Index (TCI), and Vegetation health index (VHI) as well as NDVI were used to characterize the dynamics of drought severity conditions and their fluctuations in the study area.

It was found a strong correlation between land surface temperature (LST), and TCI with VHI which indicates a definite influence of thermal stress on vegetation health in the study area. The analysis of Pearson (R), and the correlation between vegetative drought indices over the 1990–2019 period in Khorasan-e-Razavi province revealed no significant differences among drought indices except P-values.  Analyzing long-term drought indices in the study area showed high thermal stress, very poor vegetation condition, and mainly weak VHI in most years of the study.  Results from this study highlight the potential for including satellite-based drought indices in agricultural decision support systems (e.g. agricultural drought early warning systems, crop yield forecasting models, or water resource management tools) complementing meteorological drought indices derived from precipitation grids.