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<p>Climate variability and increasing extreme events are intensifying risks to water resources, agriculture, and livelihoods in the Awash Basin. However, comprehensive basin-scale assessments using observations and high-resolution bias-corrected Coupled Model Intercomparison Project Phase Six (CMIP6) projections remain limited, constraining reliable evaluation of historical trends and future extremes. This study uniquely integrates Enhanced National Climate Services (ENACTS) and bias-corrected CMIP6 ensembles to assess rainfall extremes at the basin scale in Ethiopia. Historical and future climate trends were computed using high-performance model ensembles from CMIP6 under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) for mid-century (2041–2070) and end-century (2071–2100) periods. The historical daily rainfall data were obtained from the Ethiopian Meteorological Institute (1985 to 2020) for baseline period analysis and CMIP6 bias correction. The non-parametric Mann–Kendall test was applied to detect trends with the Climate Data Tool (CDT) in R software. The ensemble of three high-performing CMIP6 models against ENACTS (1985–2014) showed strong performance (R² = 0.98, NSE = 0.94, IOA = 0.99). The historical precipitation analysis revealed that 48.1% of stations had declining annual wet day precipitation (PRCPTOT) and very wet days (R95pTOT), with notable declines at Dire Dawa (11.59&#xa0;mm and 6.41&#xa0;mm) and Errer (12.34&#xa0;mm and 8.66&#xa0;mm). On the other hand, the historical precipitation analysis result showed that 59.3% of stations had increasing consecutive dry days (CDD). More than 60% of stations projected decreasing consecutive wet days (CWD), and 78% projected declining PRCPTOT under SSP2-4.5 (2041–2070), implying shorter rainy spells. Longer dry spells in the lowland part of the basin are projected to exist with amplified short-duration extremes (increased Rx1day under SSP5-8.5 at the end of the century (2071–2100)). The coexistence of intensified heavy rainfall events with prolonged dry spells underscores rising risks of both flash floods and drought. This study emphasizes the need for implementing drought-resistant irrigation techniques, improving flood management systems, and developing basin-wide adaptation plans in the Awash Basin.</p>

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Historical and future rainfall extremes in the Awash Basin under CMIP6 projections

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月22日

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  • Elias Fiseha Mekonnen,
  • Tofikk Redi Indris,
  • Rahel Yirdaw Admasu

摘要

Climate variability and increasing extreme events are intensifying risks to water resources, agriculture, and livelihoods in the Awash Basin. However, comprehensive basin-scale assessments using observations and high-resolution bias-corrected Coupled Model Intercomparison Project Phase Six (CMIP6) projections remain limited, constraining reliable evaluation of historical trends and future extremes. This study uniquely integrates Enhanced National Climate Services (ENACTS) and bias-corrected CMIP6 ensembles to assess rainfall extremes at the basin scale in Ethiopia. Historical and future climate trends were computed using high-performance model ensembles from CMIP6 under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) for mid-century (2041–2070) and end-century (2071–2100) periods. The historical daily rainfall data were obtained from the Ethiopian Meteorological Institute (1985 to 2020) for baseline period analysis and CMIP6 bias correction. The non-parametric Mann–Kendall test was applied to detect trends with the Climate Data Tool (CDT) in R software. The ensemble of three high-performing CMIP6 models against ENACTS (1985–2014) showed strong performance (R² = 0.98, NSE = 0.94, IOA = 0.99). The historical precipitation analysis revealed that 48.1% of stations had declining annual wet day precipitation (PRCPTOT) and very wet days (R95pTOT), with notable declines at Dire Dawa (11.59 mm and 6.41 mm) and Errer (12.34 mm and 8.66 mm). On the other hand, the historical precipitation analysis result showed that 59.3% of stations had increasing consecutive dry days (CDD). More than 60% of stations projected decreasing consecutive wet days (CWD), and 78% projected declining PRCPTOT under SSP2-4.5 (2041–2070), implying shorter rainy spells. Longer dry spells in the lowland part of the basin are projected to exist with amplified short-duration extremes (increased Rx1day under SSP5-8.5 at the end of the century (2071–2100)). The coexistence of intensified heavy rainfall events with prolonged dry spells underscores rising risks of both flash floods and drought. This study emphasizes the need for implementing drought-resistant irrigation techniques, improving flood management systems, and developing basin-wide adaptation plans in the Awash Basin.