Correlation analysis of drought-dust and its relationship with vegetation changes in Khuzestan province

Drought, one of the most complex natural phenomena, causes significant direct and indirect damage to different sectors annually. The purpose of this study was to monitor drought, dust, and vegetation at five stations in the Khuzestan Province over a statistical period of 30 years (1990-2019). In this study, from the hourly data of horizontal visibility, the codes of the Meteorological Organization as well as the data of the synoptic station in the daily time frame were used to obtain the drought indices (SPEI and SPI) and the frequency variable of dust storms (DU) in time windows of 1, 3, 6, and 12 months. After calculating the indices of drought, dust and vegetation, they were combined with the empirical copula function method. The station that had the best correlation between the three climatic indices of dust-drought-vegetation was considered a representative station, and the three-variable coupling among the desired indices was investigated at that station. The results showed according to the SPI index, severe droughts occurred in the province from 1999 to 2003 and 2008 to 2012, which had a lot of negative effects on the soil of the region, as well as the formation of dust generating centers in the mentioned time period. Also, the results showed that the highest correlation was related to Bandar Mahshahr station between NDVI and SPEI (PM12) indices with Pearson and Spearman correlation coefficients of 0.44 and 0.46, respectively, and the highest negative correlation at Masjid Suleiman station between NDVI and DU06 occurred with Pearson and Spearman correlation coefficients of -0.37 and -0.47, respectively. The results obtained in Khuzestan Province are almost realistic as the drought index increased, the NDVI index increased, and as the dust increased, the NDVI value decreased.