Monitoring Meteorological Drought in Iran Using Remote Sensing and Drought Indices

Document Type : Research Paper


1 Faculty of Engineering, University of Tehran, Tehran, Iran

2 Faculty of Geography, University of Tehran, Tehran, Iran


Drought is a major environmental disaster in many parts of the world. Knowledge about the timing, severity and extent
of drought can aid planning and decision-making. Drought indices derived from in-situ meteorological data have coarse
spatial and temporal resolutions, thus, obtaining a real-time drought condition over a large area is difficult. This study
used advanced very high resolution radiometer (AVHRR) images to evaluate the efficacy of NOAA-AVHRR data for
monitoring drought in Iran for the 1997-2005 (March-July) time period. Ten-day maximum normalized difference
vegetation index (NDVI) maps were produced and a vegetation condition index (VCI), vegetation health index (VHI) and
temperature condition index (TCI) for the same period was calculated. Precipitation data from 47 synoptic meteorological
stations was collected to calculate the standardized precipitation index (SPI) as a meteorological drought index. Analysis
and interpretation of these maps revealed that the spatial extent of the satellite-derived drought-indices and SPI generally
confirm each other. Based on the statistical analysis, higher correlations were found among the satellite-derived indices
while lesser or no relationships were found between the satellite-derived indices and SPI. The results revealed that high
correlations were found among TCI and VHI, VCI and VHI in dry, normal, and wet years (0.662 to 0.813). Iran suffered
from severe drought during 1999-2001.The results of remotely-sensed indices and the SPI index for 2002-2005 most of
the region show that it experienced normal conditions.