Abeshu et al. (2026) Coupling water balance and vegetation carbon dynamics in a parsimonious global hydrologic model

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-09-01
• Authors: Guta Wakbulcho Abeshu, Hongyi Li, L.Ruby Leung
• DOI: 10.1016/j.jhydrol.2026.136520

Research Groups

• Pacific Northwest National Laboratory
• Department of Civil and Environmental Engineering and Center for Catastrophe Modeling and Resilience, Lehigh University
• Formerly at: Department of Civil and Environmental Engineering, University of Houston

Short Summary

This study demonstrates the extension of a parsimonious global hydrologic model to diagnose coupled water-carbon dynamics while retaining interpretable structure and computational efficiency. The model captures gross primary productivity (GPP) robustly and produces independently evaluated evapotranspiration (ET) skill despite ET not being used in calibration.

Objective

• To develop a parsimonious monthly hydrologic model that can represent coupled water-carbon dynamics at the global scale.
• To evaluate whether a simple conceptual hydrologic model can reproduce key patterns of both water and carbon flux variability.

Study Configuration

• Spatial Scale: Global, 0.5° spatial resolution
• Temporal Scale: Monthly, covering the period 2001–2019

Methodology and Data

• Models used:
  • abcd monthly water-balance model
  • Horton Index framework for estimating monthly ET under vegetation control
  • Two-parameter GPP–ET functional relationship
• Data sources:
  • Climate forcing from GSWP3-W5E5
  • Carbon and water fluxes (GPP and ET) from FLUXCOM-X BASE
  • Runoff from the GRUN-ensemble reconstruction

Main Results

• The model reproduces GPP robustly, with a median Kling–Gupta Efficiency (KGE) of 0.758 and positive KGE in 97.9% of basins.
• ET performance is also broadly positive despite not being directly calibrated, with a median validation KGE of 0.673 and positive KGE in 87.7% of basins.
• Runoff skill is moderate and more heterogeneous, with a median validation KGE of 0.435 and positive KGE in 81.7% of basins.

Contributions

• The study demonstrates that a parsimonious monthly hydrologic model can be extended to diagnose first-order coupled water-carbon dynamics while retaining interpretable structure and computational efficiency.
• The results show that the model strongly captures the climatological timing of GPP and ET while retaining meaningful anomaly skill after removing the mean annual cycle.

Funding

• This research was funded by [project/program name], reference code [reference code].

Citation

@article{Abeshu2026Coupling,
  author = {Abeshu, Guta Wakbulcho and Li, Hongyi and Leung, L.Ruby},
  title = {Coupling water balance and vegetation carbon dynamics in a parsimonious global hydrologic model},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136520},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136520}
}