Spatio-temporal analysis of dry and wet periods in Iran by using Global Precipitation Climatology Center-Drought Index (GPCC-DI)

Abstract

In this study, the temporal and spatial characteristics of droughts in Iran, including severity, duration, frequency, and extent, were studied using the GPCC-DI, in a 68-year period from 1952 to 2019. To display and analyze these features, time trend components, intensity, duration, and area diagrams, Mann-Kendall non-parametric test and Kriging geostatistical method were used. The result of plotting intensity-duration-frequency maps shows an increasing trend in regional drought severity and spread. It was also found that the most severe droughts occurred in the 12- and 24-month periods from 2000 onward. Mann-Kendall test results also show that significant increases in droughts occurred in the central desert basins of Hamoon basin and south Baluchistan in the southeastern Iran. In addition, decrease in occurrences of dry and wet periods happened in the western, northwestern, and coastal regions of the Caspian Sea. The pattern of spatial variations of drought severity indicated two major drought foci in southeast and central Iran. The number of drought centers in Iran has also increased over time. The results of the analysis of the time trends of dry and wet periods point to the occurrence of continuous droughts in 12- and 24-month periods.