Özel et al. (2026) Multi-dimensional Assessment of the Water-Food Nexus in a Semi-Arid Watershed

Identification

• Journal: Water Resources Management
• Year: 2026
• Date: 2026-03-01
• Authors: Beyza Özel, Yasemin Demir, Emre Alp
• DOI: 10.1007/s11269-026-04544-z

Research Groups

• Department of Environmental Engineering, Middle East Technical University, Ankara, Türkiye
• Soil, Fertilizer and Water Resources Central Research Institute, Ankara, Türkiye

Short Summary

This study holistically assesses the water-food nexus in the semi-arid Upper Sakarya Watershed, Türkiye, by integrating hydrological modeling, economic analysis, and stakeholder perspectives to evaluate agricultural water management scenarios. It finds that effective scenarios, particularly crop pattern changes, can significantly reduce irrigation water use (up to 60 million m³ per year) while increasing farmers' net income per cubic meter of water, but implementation faces technical, practical, and political constraints.

Objective

• To develop sustainable agricultural water management strategies by assessing the water-food nexus through integrated hydrological, economic, and social dimensions in the semi-arid Upper Sakarya Watershed.

Study Configuration

• Spatial Scale: Upper Sakarya Watershed, Türkiye. Drainage area approximately 21,000 km², with agricultural lands covering about 70% of the basin.
• Temporal Scale:
  • Model calibration: 2004–2012
  • Model validation: 2013–2016
  • Scenario assessment: Evaluated under varying hydrologic conditions (dry and normal years classified from 1989 to 2016 streamflow data).

Methodology and Data

• Models used: Water Evaluation and Planning System (WEAP) model for hydrological analysis.
• Data sources:
  • Satellite imagery (CORINE 2018 LULC, SRTM 1 Arc-Second Global DEM).
  • Observation data (Turkish State Meteorological Service (MGM) for climate, Streamflow Gauges data, power plant visits).
  • Reanalysis/Reports (DSİ, SYGM, TurkStat, TAGEM, World Bank reports, Annual Reports of Water and Sewerage Administrations, field studies, surveys, stakeholder interviews).

Main Results

• Water Savings: The most effective scenarios, such as shifting crop patterns from sunflower to safflower (S123), can reduce irrigation water use by up to 60 million m³ per year. Combined scenarios (C1, C2) show the highest overall impact on irrigation water supply, demand, and shortfall.
• Economic Feasibility: The most feasible scenarios (S113, S123, S116) can increase farmer's net income by €5.4–13.5 per cubic meter of water use compared to the baseline. Deficit irrigation scenarios (S31-S33) contribute up to €0.8 per cubic meter. Scenarios that promote water conservation also demonstrate positive economic contributions.
• Hydrological Conditions: Crop pattern changes (S113, S123) are more effective in reducing irrigation demand during drought years compared to normal years.
• Water Reliability: Groundwater-based demand sites achieve 100% reliability. Surface water reliability is heterogeneous (51–99%), with upstream locations generally more reliable than downstream areas (e.g., Ayvalı sub-basin at 51–60%). Combined scenarios significantly improve surface water reliability.
• Stakeholder Perspectives: Stakeholders identified technical, practical, and political constraints that could hinder the implementation and sustainability of the most effective scenarios, emphasizing the need for cost-effective irrigation modernization and remote sensing technologies.
• Integrated Evaluation: A strong correlation was found between environmental effectiveness (water savings), economic benefit, and social acceptability, indicating that scenarios performing well environmentally also tend to achieve economic and social objectives.

Contributions

• Provides an integrated, basin-scale water-food nexus evaluation that empirically links environmental impacts, socioeconomic outcomes, and governance structures in a water-stressed, semi-arid region.
• Combines hydrological modeling (WEAP), scenario design (irrigation technology, crop patterns, water-saving strategies), explicit stakeholder engagement, and producer-finance assessment within a single decision-oriented framework.
• Offers practical, policy-relevant recommendations for sustainable water governance, including reforming support schemes to reward economic water productivity, setting explicit downstream reliability targets, and prioritizing investments in delivery efficiency.

Funding

• The Scientific and Technological Research Council of Türkiye (TÜBİTAK)
  • Project title: 'Evaluation of Water, Energy and Food Nexus in Sakarya Watershed'
  • Grant number: 116Y166

Citation

@article{Özel2026Multidimensional,
  author = {Özel, Beyza and Demir, Yasemin and Alp, Emre},
  title = {Multi-dimensional Assessment of the Water-Food Nexus in a Semi-Arid Watershed},
  journal = {Water Resources Management},
  year = {2026},
  doi = {10.1007/s11269-026-04544-z},
  url = {https://doi.org/10.1007/s11269-026-04544-z}
}