Lakew et al. (2026) Multi‐Scale Analysis of July (Hamle) Rainfall Failure as an Indicator of Drought and El Niño Events in Ethiopia: A Case Study of Borkena Watershed, Awash Basin

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: International Journal of Climatology
• Year: 2026
• Date: 2026-01-02
• Authors: Haileyesus Belay Lakew, Meron Teferi Taye, A. H. Seid
• DOI: 10.1002/joc.70227

Research Groups

Not available from the provided abstract.

Short Summary

This study identified July's total rainfall failure, particularly during the Ethiopian month of Hamle, as a highly reliable in-season early-warning indicator for meteorological drought and El Niño events across multiple scales in the Awash Basin, Ethiopia.

Objective

• To determine the most relevant rainfall-based indicator of historical meteorological drought in relation to El Niño events across multiple spatial and temporal scales in the Awash Basin, Ethiopia.

Study Configuration

• Spatial Scale: Awash Basin (110,000 km²), Borkena sub-basin (3,250 km²), and local livelihood zones (36–927 km²).
• Temporal Scale: Historical precipitation data from 1981–2021 (41 years), analyzed at monthly and dekadal (10-day) scales, with rainfall classified into three dekads per month.

Methodology and Data

• Models used: Signal Detection Theory (SDT) metrics, including True Positive Rate (TPR), False Positive Rate (FPR), and Competence (C).
• Data sources: CHIRPS dataset (historical precipitation data, 1981–2021).

Main Results

• July's total rainfall failure consistently aligns with historical droughts and El Niño events across all spatial scales.
• High detection performance for July rainfall failure was observed, with TPR > 70%, FPR < 30%, and C > 40%.
• In the Borkena watershed, detection performance improved when focusing on the second and third dekads of July and the first dekad of August (corresponding to the Ethiopian month of Hamle).
• Maximum performance in the Borkena watershed for the Hamle period achieved TPR = 90%, FPR = 10%, and C = 80%.
• These findings demonstrate that July rainfall failure, especially during Hamle, can serve as an in-season early-warning signal for meteorological drought.

Contributions

• Identifies a specific and reliable in-season rainfall-based early-warning signal (July rainfall failure, particularly during Hamle) for meteorological drought and El Niño events in the Awash Basin.
• Provides quantitative performance metrics (TPR, FPR, C) for this indicator across various spatial and temporal scales, enhancing its practical applicability.
• Offers a crucial tool for timely drought response and water resource management in rainfed agricultural regions like Ethiopia.

Funding

Not available from the provided abstract.

Citation

@article{Lakew2026MultiScale,
  author = {Lakew, Haileyesus Belay and Taye, Meron Teferi and Seid, A. H.},
  title = {Multi‐Scale Analysis of July (Hamle) Rainfall Failure as an Indicator of Drought and El Niño Events in Ethiopia: A Case Study of Borkena Watershed, Awash Basin},
  journal = {International Journal of Climatology},
  year = {2026},
  doi = {10.1002/joc.70227},
  url = {https://doi.org/10.1002/joc.70227}
}