Trivariate risk analysis of meteorological drought in Iran under climate change scenarios

The aim of this study is to analyze the trivariate risk of meteorological drought using copula functions under climate change scenarios in Iran. For this purpose, SPI-12 is calculated for the historical and future periods and the drought characteristics [severity (S)–duration (D) and magnitude (M)] are extracted and the trend analysis of drought characteristics is performed using Mann–Kendall trend test. Then, trivariate risk analysis of drought variables is performed for historical and future periods. The results of the trend test indicate that the precipitation trend decreased mostly in the northwest and west regions of Iran, while these changes in the future period will be observed in the central regions. According to the results, no significant trend in precipitation and drought characteristics will be observed in the future compared to the historical period. Trivariate risk analysis for the given values of ( D = 6, S > 40, M = 2) and ( D = 12, S > 40, M = 2) shows that for the given values of severity and duration, increasing duration from D = 6 to D = 12 months, decreases the probability of drought occurrence and return period. Therefore, the conditional risk will increase in Iran under future climate change scenarios.