drought monitoring using vegetation indices and modis data (case study: isfahan province, iran)

drought is a major problematic phenomenon mostly for semi-arid areas of iran. during drought periods, reduction in vegetation levels causes such problems as soil erosion, surface runoff, flood risk, etc. therefore, the assessment of drought effects on plant covers is the most important issue. this research was conducted in 2015 using the extracted vegetation indices from moderate resolution imaging spectroradiometer (modis) sensor data during 2000-2008. in esfahan province, monthly rainfall data from 25 stations were used to derive the standardized precipitation index (spi) at 3 month scale, march to september. spi was used to validate three index results in drought estimation. the result of calculating spi showed that droughts occurred in 2000, 2001 and 2008. the result of pearson correlations between spi and vegetation indices showed thatthe highest correlation was related to vci index and the lowest correlation was related to tci index. the result of ndvi index in 2000, 2001 and 2008 indicated that the poor vegetation cover was increasingly occurred. based on the results of this study, it can be concluded that the ndvi and vci indices concerning modis sensor can be a good alternative for estimating the drought with respect to meteorological indices and consequently can give a better idea on drought conditions in the study area. it was shown that remote sensing data can be practically useful in analyzing the drought events in esfahan province.