Wagle et al. (2026) Partitioning evapotranspiration in C3-C4 mixed tallgrass prairies: An inter-comparison of five methods and evaluation of seasonal parameterization

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-07-07
• Authors: Pradeep Wagle, Pushpendra Raghav, Mukesh Kumar, Todd M. Scanlon, Brian K. Northup, Corey A. Moffet, Xiangming Xiao, S. A. Gunter
• DOI: 10.1016/j.agwat.2026.110616

Research Groups

• USDA, Agricultural Research Service, Oklahoma and Central Plains Agricultural Research Center, El Reno, OK, USA
• Department of Civil, Construction, and Environmental Engineering, University of Alabama, Tuscaloosa, AL, USA
• Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA
• Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA

Short Summary

This study inter-compared five evapotranspiration (ET) partitioning methods in mixed C3-C4 tallgrass prairies: Flux Variance Similarity (FVS), Modified Relaxed Eddy Accumulation (MREA), Conditional Eddy Covariance (CEC), Conditional Eddy Accumulation (CEA), and a water-use efficiency-integrated modification of CEC (CECw). The results showed that MREA and CEC estimated T 10–20% higher than biophysically reasonable estimates from FVS and CEA.

Objective

• Investigate the performance of five ET partitioning methods in mixed C3-C4 tallgrass prairies.
• Evaluate how these methods compare against purely turbulence-driven or statistical approaches in mixed vegetative systems.

Study Configuration

• Spatial Scale: Two differently managed native tallgrass prairie pastures (grazed vs. hay harvest) located at the United States Department of Agriculture – Agricultural Research Service, Oklahoma and Central Plains Agricul­ tural Research Center, El Reno, OK.
• Temporal Scale: Annual and seasonal scales.

Methodology and Data

• Models used:
  • Flux Variance Similarity (FVS)
  • Modified Relaxed Eddy Accumulation (MREA)
  • Conditional Eddy Covariance (CEC)
  • Conditional Eddy Accumulation (CEA)
  • A water-use efficiency-integrated modification of CEC (CECw)
• Data sources:
  • Eddy covariance measurements from two differently managed native tallgrass prairie pastures in Oklahoma, USA.
  • Lysimeter-measured evaporation data at the National Ecological Observatory Network’s Konza Prairie site in Kansas, USA.

Main Results

• MREA and CEC estimated T 10–20% higher than biophysically reasonable estimates from FVS and CEA.
• The T:ET ratios were higher during the growing season (April-October) due to increases in T and decreases in solar radiation on the soil surface as canopy coverage increases.
• The persistently high T:ET ratios and low temporal variability characteristic of MREA and CEC estimates suggest a systematic underestimation of E.

Contributions

• This study provides an intercomparison of five ET partitioning methods across two differently managed (grazed vs. hay harvest) mixed C3:C4 prairie sites in Central Oklahoma, USA.
• The results demonstrate that the choice of method significantly influences the resulting ecosystem water budget.

Funding

• USDA, Agricultural Research Service
• National Science Foundation

Citation

@article{Wagle2026Partitioning,
  author = {Wagle, Pradeep and Raghav, Pushpendra and Kumar, Mukesh and Scanlon, Todd M. and Northup, Brian K. and Moffet, Corey A. and Xiao, Xiangming and Gunter, S. A.},
  title = {Partitioning evapotranspiration in C3-C4 mixed tallgrass prairies: An inter-comparison of five methods and evaluation of seasonal parameterization},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110616},
  url = {https://doi.org/10.1016/j.agwat.2026.110616}
}