Bekele (2025) Review on Crop Water Requirements in Ethiopia

Identification

• Journal: Research and Innovation
• Year: 2025
• Date: 2025-12-26
• Authors: Getachew Bekele
• DOI: 10.11648/j.ri.20260201.13

Research Groups

• Department of Water Resources and Irrigation Engineering, Gambella University, Ethiopia.

Short Summary

This paper reviews the methodologies and challenges of estimating crop water requirements (CWR) in Ethiopia, emphasizing the need for localized calibration and integrated water management. It identifies that while the FAO-56 Penman-Monteith method is the standard, its accuracy is hindered by sparse meteorological data and the neglect of rain-fed "green water" contributions.

Objective

• To synthesize existing research on crop water requirements in Ethiopia, evaluate estimation methodologies (CROPWAT, remote sensing, empirical formulas), and identify data gaps necessary for climate-resilient irrigation planning.

Study Configuration

• Spatial Scale: National level (Ethiopia), with specific focus on diverse agro-ecological zones including the central highlands, the Rift Valley, and major river basins (Awash and Abay).
• Temporal Scale: Review of contemporary literature and future climate projections (mid-century) under moderate emission pathways (RCP4.5).

Methodology and Data

• Models used: FAO-56 Penman-Monteith (standard), CROPWAT, Aqua-Crop, and remote sensing-based models (SEBAL, GLEAM).
• Empirical formulas: Hargreaves and Blaney-Criddle (used in data-scarce conditions).
• Data sources: Ground-based meteorological stations (temperature, humidity, wind speed, solar radiation), satellite imagery (MODIS), and climate model projections (CMIP6).

Main Results

• Crop-Specific Requirements: Seasonal water demand for cereals like wheat and teff ranges from 350 mm to 500 mm, while maize and sorghum require 500 mm to 700 mm.
• Spatial Variability: Highland regions exhibit lower reference evapotranspiration (ETo) due to cooler temperatures, whereas arid lowlands and the Rift Valley show significantly higher ETo and irrigation demand.
• Climate Change Impact: Projections indicate a 10% to 20% increase in irrigation water demand by mid-century due to rising temperatures and shifting precipitation patterns.
• Data Limitations: Significant uncertainties arise from the use of generic crop coefficients (Kc) and the lack of continuous meteorological observations in rural and lowland areas.
• Green vs. Blue Water: Although 70% of Ethiopian agriculture is rain-fed, most studies focus on "blue water" (irrigation), leading to incomplete assessments of total water availability.

Contributions

• Provides a comprehensive critique of the over-reliance on uncalibrated FAO-56 parameters in the Ethiopian context.
• Highlights the necessity of developing locally calibrated, stage-specific crop coefficients for indigenous and major crops (e.g., teff, sorghum).
• Proposes an integrated framework that accounts for both green water (soil moisture) and blue water to improve national food security and water allocation policies.

Funding

• The author declares that the research was conducted independently; no specific funding projects or reference codes were provided.

Citation

@article{Bekele2025Review,
  author = {Bekele, Getachew},
  title = {Review on Crop Water Requirements in Ethiopia},
  journal = {Research and Innovation},
  year = {2025},
  doi = {10.11648/j.ri.20260201.13},
  url = {https://doi.org/10.11648/j.ri.20260201.13}
}

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