Document Type : Original Article
Authors
1 natural resources
2 University of Hormozgan
Abstract
Composite droughts, which simultaneously affect both meteorological systems and water resources, pose a serious threat to arid and semi-arid regions. This study aimed to model droughts under future climate change scenarios using copula functions. Historical data (1989–2020) and statistically downscaled outputs from the CanESM5 climate model under SSP126, SSP370, and SSP585 scenarios for the future period (2021–2040) were utilized. Watershed runoff was simulated using the IHACRES model. P-12 and R-12 were calculated, and a joint hydro-meteorological drought index (JDHMI) was developed using copula functions. Drought characteristics (frequency, intensity, duration, and magnitude) and trends were analyzed for both historical and future periods. Results indicated that the composite JDHMI exhibited less fluctuation compared to univariate indices, providing a more stable and comprehensive depiction of drought conditions. Under climate change scenarios, the drought pattern is projected to shift from fewer but longer and more severe droughts to more frequent, shorter-duration droughts, particularly under the SSP585 scenario. Although average duration and intensity decreased in some scenarios, the drought "magnitude" index—integrating intensity and duration—increased across all future scenarios, indicating an overall intensification of drought content. Furthermore, the frequency of "severe" droughts significantly increased under all scenarios. Trend analysis confirmed a significant and accelerating decline in the JDHMI index in the future. This framework can serve as a scientific basis for early warning systems, and sustainable water resource management in the face of climate change.
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