Determining the correlation between NDVI and EVI vegetation indices and SPI drought index (Case Study: Golestan rangelands)

In this study the relationship between annual Standard Precipitation Index (SPI) and, remotely sensed indices of Enhanced Vegetation Index (EVI) and Normalized Differencing Vegetation Index (NDVI) have been studied. MODIS images of Terra satellites for the period of 2000 to 2012, during the growing season of pastures across Golestan province alongwith rainfall data of five meteorological stations in Golestan rangelands from their establishment till 1993 were collected. Pearson correlation coefficient was used to assess the relationship between rainfall data and vegetations indices. Correlation coefficient between (SPI) drought index and EVI and NDVI indices was 0.75 and 0.78 respectively at 5% level of significance. Bedsides, correlation between the NDVI and EVI indices in detection of the vegetation changes were 0.98. In general, the results of this study showed that in regions with inadequate rainfall data, remote sensing products can be used for drought and vegetation cover dynamic monitoring.