Meresa et al. (2026) Climate Change and Irrigation Effects on Hydrology and Crop Yield in the Geba Watershed, Tigray Region, Northern Ethiopia

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Identification

• Journal: Hydrology
• Year: 2026
• Date: 2026-08-03
• Authors: Adane Weldengus Meresa, Muuz Gebretsadik Gebremariam, Anthony Lehmann, M Jafari
• DOI: 10.3390/hydrology13080208

Research Groups

Not specified in the provided text.

Short Summary

This study evaluates the combined impacts of future climate change and irrigation expansion on the hydrology and crop yields of the Geba watershed in northern Ethiopia using the SWAT+ model. The findings indicate that while irrigation is intended to support agriculture, it may exacerbate hydrological stress by significantly reducing groundwater recharge and water yield.

Objective

• To quantify the effects of future climate change (RCP 4.5 and RCP 8.5) and irrigation management (rainfed vs. irrigation-rainfed integrated) on watershed hydrological processes and agricultural productivity.

Study Configuration

• Spatial Scale: Geba watershed, northern Ethiopia (semi-arid region).
• Temporal Scale: Calibration and validation period (2006–2020); future projections for mid-century (2046–2060) and late-century (2086–2100).

Methodology and Data

• Models used: Soil and Water Assessment Tool Plus (SWAT+).
• Data sources: Observed daily streamflow data (2006–2020) and an ensemble of five bias-corrected CORDEX Africa regional climate models (RCMs) under RCP 4.5 and RCP 8.5 scenarios.

Main Results

• Hydrological Shifts: A transition toward an evapotranspiration-dominated regime is expected. Under rainfed management, surface runoff and evapotranspiration increased by up to 60% and 30%, respectively.
• Irrigation Impact: Irrigation expansion intensified hydrological stress, reducing percolation by up to 80%, lateral flow by up to 60%, and water yield by up to 55%.
• Drivers of Variability: Climate forcing, management type, and their interactions significantly influenced responses (p < 0.001), with emission pathways being the dominant driver.
• Crop Productivity:
  • Rainfed maize and wheat showed moderate yield increases in the mid-century.
  • Teff exhibited high vulnerability with consistent negative responses to warming and moisture stress.
  • Under irrigation, most crops saw yield reductions in the late-century, though tomatoes showed localized gains under high-emission scenarios.

Contributions

The study provides critical evidence that irrigation expansion alone is an unsustainable adaptation strategy in semi-arid Ethiopian watersheds, as it reduces groundwater recharge and intensifies evapotranspiration. It emphasizes the need for integrated watershed management and climate-resilient crop selection.

Funding

Not specified in the provided text.

Citation

@article{Meresa2026Climate,
  author = {Meresa, Adane Weldengus and Gebremariam, Muuz Gebretsadik and Lehmann, Anthony and Jafari, M},
  title = {Climate Change and Irrigation Effects on Hydrology and Crop Yield in the Geba Watershed, Tigray Region, Northern Ethiopia},
  journal = {Hydrology},
  year = {2026},
  doi = {10.3390/hydrology13080208},
  url = {https://doi.org/10.3390/hydrology13080208}
}