Research Article
Spatial and Temporal Characteristics of Wet and Dry Spells During the Kiremt Season Over Ethiopia
Habtam Jenberu Wassie*
,
Samrawit Abebe Angasso
Issue:
Volume 1, Issue 4, December 2026
Pages:
166-178
Received:
24 September 2026
Accepted:
8 October 2026
Published:
26 October 2026
Abstract: The understanding of changes of rainfall patterns and climate extremes are crucial factors for addressing agricultural risks and sustaining water resources in Ethiopia. This study aims to investigate baseline rainfall climatology (1991-2020) and long-term spatiotemporal changes (1981-2022) of Kiremt seasonal rainfall totals (PRCPTOT) and selected ETCCDI-based rainfall indices across Ethiopia. The daily rainfall was analyzed using the Mann-Kendall test and Sen’s slope estimator to examine changes of wet and dry spell frequencies (NWS and NDS), spell durations (MWSL and MDSL) and total wet and dry days (TWD and TDD) from gridded and gauge-based datasets. The baseline climatology reveals a clear rainfall gradient with seasonal totals over 800 mm and more than 80 wet days in western highlands, while less than 400 mm and maximum dry spells over 80 days observed in the eastern lowlands. Kiremt rainfall significantly increased at a national scale by 2.56 mm/year (p = 0.004), specifically the central, western and northern highlands. However, the wet- and dry-spell frequencies increased while the maximum wet-spell duration showed no consistent trend while the total wet days declined recently. These changes suggest greater intra-seasonal rainfall variability with concentrated rainfall and frequent dry spells influencing risks of soil erosion, runoff, and water stress and crop yields. Therefore, it requires soil-moisture conservation, rainwater harvesting and climate-smart agricultural practices.
Abstract: The understanding of changes of rainfall patterns and climate extremes are crucial factors for addressing agricultural risks and sustaining water resources in Ethiopia. This study aims to investigate baseline rainfall climatology (1991-2020) and long-term spatiotemporal changes (1981-2022) of Kiremt seasonal rainfall totals (PRCPTOT) and selected E...
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Research Article
Hydroclimate Variability at Lake Tana, Ethiopia, Over the Past 6,000 Years: A Critical Synthesis of Geochemical and Isotopic Records
Belay Sitotaw Goshu*
Issue:
Volume 1, Issue 4, December 2026
Pages:
179-193
Received:
18 September 2026
Accepted:
28 September 2026
Published:
29 October 2026
Abstract: Lake Tana, the source of the Blue Nile in the northwestern Ethiopian highlands, is a climatically sensitive archive at the northern margin of the Intertropical Convergence Zone (ITCZ). Its sediments record changes in the balance between Atlantic/Congo Basin moisture and Indian Ocean/Red Sea moisture, making it a key site for understanding Afro-Asian monsoon dynamics. This review critically synthesizes geochemical (XRF element ratios: Zr/Rb, Ca/Ti, Rb/K) and isotopic (leaf-wax δD) records from Lake Tana to reconstruct hydroclimate variability over the past 6,000 years, evaluate proxy reliability, and identify research gaps. Available evidence indicates that the African Humid Period (AHP) terminated at Lake Tana by approximately 8,000 cal BP, significantly earlier than in the Sahara and North Africa (~5,000 cal BP), δDwax records indicate that this transition was driven by eastward migration of the Congo Air Boundary (CAB), not solely by ITCZ southward retreat. Late Holocene aridification culminated in a pronounced low-stand at ~4,200 cal BP, coeval with the Egyptian Old Kingdom collapse. Existing XRF data (366–150,190 yr) provide a foundation but lack the sampling density needed to resolve centennial-scale variability in the past 6,000 years, and no dedicated high-resolution study exists for the past 2,000 years, a period encompassing the Aksumite civilization and the Little Ice Age. A dedicated high-resolution geochemical and isotopic study is urgently needed to address outstanding questions about natural variability versus anthropogenic impact, and to provide a longer historical context for water resource management in the Blue Nile basin under future global warming.
Abstract: Lake Tana, the source of the Blue Nile in the northwestern Ethiopian highlands, is a climatically sensitive archive at the northern margin of the Intertropical Convergence Zone (ITCZ). Its sediments record changes in the balance between Atlantic/Congo Basin moisture and Indian Ocean/Red Sea moisture, making it a key site for understanding Afro-Asia...
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