Spatial evaluation of climate change-induced drought characteristics in different climates based on De Martonne Aridity Index in Iran

Abstract

In recent years, greenhouse gas emissions have caused extensive changes in the global climate. Climate change leads to extreme events, such as droughts. The present study investigates precipitation and temperature variations and the past and future drought characteristics in Iran through data from 40 synoptic stations and 33 general circulation models (GCMs) under RCP4.5 and RCP8.5 scenarios. As a first step, the country of Iran was classified into different climatic regions based on De Martonne aridity index. The GCMs were ranked using TOPSIS in four climatic regions and an ensemble of top ten GCMs was used in each region. Furthermore, the homogeneity of monthly precipitation was studied in the baseline and future periods. Meteorological drought was calculated through the standardized precipitation index (SPI), deriving drought severity, peak, and duration based on run theory. The results revealed that precipitation will reduce in future periods in the majority of Iran and temperature will reduce in the south and southeast and will increase in the northwest and north of Iran. Furthermore, the highest drought severity and peaks will occur in semi-arid and arid regions, while the longest drought duration will happen in the southeast and west of Iran. Overall, future droughts are found to have higher severity, duration, peaks, and standard deviation than the baseline period. Also, the results showed a reducing trend of the SPI values in northwestern regions, while the other stations indicated no significant trend.