ASSESSING CLIMATE CHANGE PROJECTION IMPACTS ON PRECIPITATION IN THE BLUE NILE BASIN USING Reg-CM4 SIMULATIONS

Youssef, Dina Ibrahim; Mansour, Sohier Ahmed; Anwer, Nabil Mohamed

doi:10.21608/auej.2025.359285.1777

ASSESSING CLIMATE CHANGE PROJECTION IMPACTS ON PRECIPITATION IN THE BLUE NILE BASIN USING Reg-CM4 SIMULATIONS

Document Type : Original Article

Authors

¹ National Water Research Center, Ministry of Water Resources and Irrigation, Qalyubia, 13621, Egypt.

² Sanitary & Environmental Eng. Dept., Faculty of Engineering at Mataria, Helwan University, Cairo, Egypt.

10.21608/auej.2025.359285.1777

Abstract

The Blue Nile Basin (BNB) is a crucial water resource for Ethiopia, Sudan, and Egypt, making it essential to assess climate change impacts on precipitation for effective water management. This study evaluates future precipitation changes using regional climate projections from the CORDEX-CMIP5 dataset with the RegCM4.3 model under RCP2.6 and RCP8.5 scenarios for two periods: 2041–2070 and 2071–2100. Bias correction was applied using a linear function based on historical simulations (1981–2005). The study analyzed seasonal precipitation distribution, Z-score, and Precipitation Concentration Index (PCI). Results indicate an overall decline in annual precipitation under both scenarios, with the most significant reduction (-15%) projected for 2071–2100 under RCP8.5. Seasonal variations show a decline in Kiremt (rainy) and Belg (semi-rainy) seasons (-14%, -34%) under RCP8.5, while the Dry season (Bega) shows a slight increase (11%), suggesting potential shifts in seasonal hydrological patterns. The Z-score analysis indicates stable normal-year occurrences but an increase in dry years at the expense of wet years for most stations. SPCI values for Kiremt were mostly ‘uniform’ in the historical period but ranged from ‘uniform’ to ‘moderate’ in future projections. Annual PCI values, which were ‘irregular’ to ‘strongly irregular’ historically, show a tendency toward more ‘strongly irregular’ values in the future. Overall, the study concludes that precipitation patterns in the BNB will change, increasing seasonal variability. Future research should refine climate projections with updated models and integrate socio-economic factors to enhance adaptation strategies and mitigate climate change impacts.

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