Louis et al. (2025) A new approach in monitoring regional water use efficiency in response to climate variability: a case study in Hungary

Identification

• Journal: Journal of Agriculture and Food Research
• Year: 2025
• Date: 2025-10-31
• Authors: Ansu Louis, Zsolt Zoltán Fehér, János Tamás, Attila Nagy
• DOI: 10.1016/j.jafr.2025.102497

Research Groups

• Institute of Water and Environmental Management, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Hungary
• National Laboratory for Water Science and Water Safety, Institute of Water and Environmental Management, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Hungary

Short Summary

This study develops and evaluates a novel biomass soil moisture index (NWUESM) as a simpler and less expensive alternative to the standard regional water use efficiency (RWUEEC) indicator, demonstrating its superior accuracy at 60 cm soil depth for monitoring water use efficiency in northeastern Hungary.

Objective

• Develop and evaluate a novel biomass soil moisture index (NWUESM) as a simpler, less expensive, and scalable alternative to the standard regional water use efficiency (RWUEEC) indicator.
• Illustrate how water use efficiency (WUE) fluctuates with seasonal changes and varying moisture conditions during cropping periods.

Study Configuration

• Spatial Scale: A section of the Tisza-Körös valley irrigation system region (TIKEVIR) measuring 4111.59 square kilometers in northeastern Hungary.
• Temporal Scale: Five consecutive cropping periods from 2018 to 2022 (March to October annually).

Methodology and Data

• Models used:
  • Fourier series regression model (dual harmonic approach)
  • Penman-Monteith equation (used by MODIS for ET estimation)
  • Light-use efficiency (LUE) model (used by MODIS for GPP estimation)
• Data sources:
  • Satellite:
    • MODIS/MCD43A4006NDVI (Normalized Difference Vegetation Index)
    • MODIS/006/MOD16A2 (Evapotranspiration - ET)
    • MODIS/006/MOD17A2H (Gross Primary Productivity - GPP)
  • Observation (Ground-based):
    • Volumetric soil moisture content (SM) at 30 cm and 60 cm depths from Hungarian drought monitoring services and KITE meteorological stations (using Time-Domain Reflectometry - TDR).
    • Meteorological data (rainfall) from Hungarian drought monitoring services and KITE.

Main Results

• The newly developed biomass soil moisture index (NWUESM) at both 30 cm and 60 cm soil depths showed consistent positive correlation and alignment with the benchmark regional water use efficiency (RWUEEC) trends over time.
• NWUESM at 60 cm depth demonstrated superior accuracy and reliability compared to NWUESM at 30 cm depth as a proxy for computing and predicting RWUEEC.
• Correlation between RWUEEC and predicted regional WUE (RWUEEC Pred) at 60 cm yielded high R² values (e.g., 0.9956 for 2018, 0.9486 for 2020, and 0.9452 for 2022) with lower Root Mean Square Error (RMSE) values (e.g., 0.038 gC·m⁻²·mm⁻¹ for 2018, 0.0686 gC·m⁻²·mm⁻¹ for 2020, and 0.0576 gC·m⁻²·mm⁻¹ for 2022).
• In contrast, RWUEEC Pred at 30 cm yielded lower R² values (e.g., 0.761 for 2022) and higher RMSE values (e.g., 0.2529 gC·m⁻²·mm⁻¹ for 2022).
• Water productivity (WUE) typically peaked around June and July in the test area, reflecting optimal growing conditions for crops.
• Deeper soil moisture at 60 cm is more stable and a better indicator of available water to crops throughout the growing season than shallow soil moisture at 30 cm.

Contributions

• Development of a novel, computationally simple, low-cost, and scalable biomass soil moisture index (NWUESM) using readily available satellite (NDVI) and ground-based soil moisture data.
• Provides a more sensitive representation of ecosystem WUE during dry spells, irrigation events, and crop growth cycles compared to traditional Gross Primary Productivity (GPP) to Evapotranspiration (ET) ratios and other modeled indices.
• Offers an innovative and empirical approach to bridge the gap between physiological realism and spatial monitoring for agricultural water management.
• Demonstrates the superior predictive power of NWUESM at 60 cm soil depth for regional WUE, recommending irrigation to reach this depth for optimal water use efficiency.

Funding

• RRF 2.3.1 21 2022 00008 project
• Széchenyi Plan Plus Program framework
• János Bolyai Research Scholarship of the Hungarian Academy of Sciences

Citation

@article{Louis2025new,
  author = {Louis, Ansu and Fehér, Zsolt Zoltán and Tamás, János and Nagy, Attila},
  title = {A new approach in monitoring regional water use efficiency in response to climate variability: a case study in Hungary},
  journal = {Journal of Agriculture and Food Research},
  year = {2025},
  doi = {10.1016/j.jafr.2025.102497},
  url = {https://doi.org/10.1016/j.jafr.2025.102497}
}

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