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...
Show More
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...
Show More
Research Article
Spatiotemporal Patterns and Projected Changes in Rainfall and Temperature Over the Harari Region, Ethiopia
Yimer Assefa Yimam*,
Melaku Takele Tegene
Issue:
Volume 1, Issue 4, December 2026
Pages:
194-214
Received:
22 July 2026
Accepted:
3 August 2026
Published:
31 October 2026
DOI:
10.11648/j.sdenv.20260104.13
Downloads:
Views:
Abstract: Climate variability and climate change pose major challenges to sustainable development in Ethiopia, particularly in regions that depend heavily on rain-fed agriculture. This study investigated the historical (1985-2025) and projected (2041-2100) spatiotemporal variability of rainfall and temperature across the Harari Region using high-resolution observational datasets (Ethiopian Meteorological Institute (EMI), obtained through the Enhancing National Climate Services (ENACTS) dataset rainfall and temperature) together with statistically downscaled CMIP6 multi-model ensembles under the SSP2-4.5 and SSP5-8.5 scenarios. Historical trends were evaluated using the Modified Mann-Kendall test and Sen's slope estimator, while rainfall variability was characterized using the Coefficient of Variation (CV) and Precipitation Concentration Index (PCI). Results indicate significant warming trends in maximum, minimum, and mean temperatures throughout most months of the historical period. Rainfall exhibited pronounced seasonal variability, with significant decreases during February, March, April, and December, while annual rainfall remained moderately variable (CV = 20.5%) with moderate rainfall concentration (PCI = 11.88). Spatial analyses revealed higher rainfall and lower temperatures over the western highlands and warmer, relatively drier conditions in the eastern lowlands. Future CMIP6 projections indicate continued warming under both emission scenarios, with substantially greater increases under SSP5-8.5. Annual rainfall is projected to increase by approximately 9.6-42.7% under SSP2-4.5 and 14.7-58.2% under SSP5-8.5, although considerable interannual variability persists. The projected warmer and generally wetter climate may enhance water availability but simultaneously increase the risks of floods, soil erosion, heat stress, and agricultural uncertainty. The findings provide high-resolution climate information that can support evidence-based adaptation planning, climate-resilient agriculture, and integrated water resource management in the Harari Region.
Abstract: Climate variability and climate change pose major challenges to sustainable development in Ethiopia, particularly in regions that depend heavily on rain-fed agriculture. This study investigated the historical (1985-2025) and projected (2041-2100) spatiotemporal variability of rainfall and temperature across the Harari Region using high-resolution o...
Show More
