Bushehr Drought Monitoring Based on SPI and VCI Indicators Using MODIS Sensor Images

Drought is a creepy phenomenon, reversible climate and an unavoidable reality in different climates that is caused by a lack of rainfall over a period of time. The purpose of this research is to monitor in Bushehr province based on SPI and VCI indices using MODIS sensors. In this regard, using 54 time-series images of the Normalized Vegetation Difference Index (NDVI) of MODIS satellite products from the growing seasons (January, February and March) between 2001 and 2018, the VCI, Vegetation Status Index, which is a normalized index to assess drought is calculated. Then, the standard SPI precipitation index for 5 synoptic stations (Borazjan, Bushehr, Deylam, Dayyer and Jam) was calculated during an 18-year statistical period, and according to the SPI classification table, very severe drought, severe drought, drought Moderate, almost normal, moderate wet, very wet and very severe wet were divided. Then the correlation coefficient of these two indices was calculated and it was found that the two indices have a significant correlation coefficient. The results of drought monitoring showed that during this 18-year period, in some years, the VCI index of severe drought (2009) shows that less rainfall occurred in the same year, and in 2014 it shows a very severe wet season where significant rainfall has occurred. Also, the results of the correlation between these two indices showed that the six-month SPI correlation coefficient has a higher correlation with the average VCI index than the quarter. In general, it was found that in the absence of meteorological indicators, a satellite index can be used to monitor drought.