He et al. (2025) A three-dimensional Budyko framework with terrestrial water storage dynamics: mechanistic modeling and diagnostic ecohydrological applications across global basins

Identification

• Journal: Ecological Indicators
• Year: 2025
• Date: 2025-10-31
• Authors: Qing He, Hok Sum Fok, Hao Zhou, Vagner G. Ferreira, Yilin Sun
• DOI: 10.1016/j.ecolind.2025.114357

Research Groups

• MOE Key Laboratory of Fundamental Physical Quantities Measurement & Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF and School of Physics, Institute of Geophysics, Huazhong University of Science and Technology, Wuhan, China
• MOE Key Laboratory of Geospace Environment and Geodesy and MNR Key Laboratory of Geophysical Geodesy, School of Geodesy and Geomatics, Wuhan University, Wuhan, China
• Hubei Luojia Laboratory, Wuhan, China
• School of Earth Sciences and Engineering, Hohai University, Nanjing, China

Short Summary

This study introduces a novel three-dimensional (3D) Budyko framework that mechanistically incorporates terrestrial water storage changes (TWSC) as a dynamic third dimension. The framework significantly improves water partitioning prediction accuracy globally, especially in tropical basins, and establishes the Water Storage Change Index (WSCI) as a powerful diagnostic indicator for anthropogenic impacts on the water cycle and ecological water stress.

Objective

• Derive a physically-based, analytical 3D Budyko equation that incorporates TWSC as a third dimension.
• Evaluate its performance against classical and extended 2D Budyko equations across global diverse river basins.
• Demonstrate the efficacy of the WSCI as a diagnostic indicator for quantifying anthropogenic disturbances and monitoring ecological water stress.

Study Configuration

• Spatial Scale: Global, covering ten major river basins and four additional human-managed basins. Data resolutions include 0.25° × 0.25° (ERA5, GRACE, GLDAS) and 0.05° × 0.05° (MODIS NDVI), with some MODIS products at 500 m.
• Temporal Scale: Monthly time step, with analysis conducted over the common overlapping period from April 2002 to June 2017.

Methodology and Data

• Models used:
  • Three-dimensional (3D) bimodal storage-regulated Budyko equation
  • Classical two-dimensional (2D) Budyko equation
  • Extended two-dimensional (2D) Budyko equation
  • Local Indicators of Spatial Association (LISA) for WSCI-NDVI analysis
• Data sources:
  • Satellite:
    • MODIS MOD16A2GF (Evapotranspiration (ET), Potential Evapotranspiration (PET))
    • MODIS MOD13C2 (Normalized Difference Vegetation Index (NDVI))
    • GRACE CSR level-2 RL06 (Terrestrial Water Storage Changes (TWSC))
    • GRACE JPL Mascon (TWSC, for validation)
  • Reanalysis:
    • ERA5 single level monthly averaged datasets (Precipitation (P), ET, PET)
    • Global Land Data Assimilation System (GLDAS) Noah v2.1 (TWSC, excluding anthropogenic groundwater signals)
  • Ancillary: HydroBASINS (river basin boundaries)

Main Results

• The 3D Budyko framework significantly outperforms classical and extended 2D models, achieving robust accuracy in mid- and low-latitude basins (Pearson Correlation Coefficient (PCC): 0.7–0.9, Root Mean Square Error (RMSE): 0.7–3.9, Nash-Sutcliffe Efficiency (NSE): 0.4–0.9), with accuracy improvements of 55–250 % in tropical basins.
• The framework effectively resolves critical failures of classical 2D models in humid, high-vegetated systems (e.g., Congo, Amazon), where the classical model yielded negative NSE values.
• Substituting GRACE-derived TWSC with GLDAS-derived TWSC (which excludes anthropogenic groundwater signals) dramatically improved 3D Budyko performance in human-disturbed basins (e.g., Yellow, Indus, Tigris-Euphrates), confirming the climate-dominated mechanism of the Budyko framework.
• The Water Storage Change Index (WSCI = TWSC/P) is a powerful diagnostic ecohydrological indicator; the deviation between observed (GRACE-based) and climate-driven (GLDAS-based) WSCI quantitatively measures anthropogenic distortion of the natural water cycle.
• Spatial association analysis between WSCI and NDVI revealed distinct ecohydrological coupling patterns: natural synergy (High-High), natural stress (Low-Low), and critically, human-induced unsustainability (Low-High clusters in major agricultural zones like the North China Plain, Punjab, and Turkish/Syrian irrigation projects) where high vegetation greenness coexists with water storage depletion.

Contributions

• Developed a novel, physically-based, analytical 3D Budyko equation that mechanistically integrates terrestrial water storage changes (TWSC) as a dynamic third dimension, advancing beyond previous empirical or statistical 3D Budyko concepts.
• Demonstrated superior global predictive accuracy of the 3D framework, particularly in non-steady-state conditions and human-impacted regions where classical and extended 2D models fail.
• Established the Water Storage Change Index (WSCI) as a powerful diagnostic tool capable of quantifying anthropogenic disturbances and distinguishing between climate-driven water scarcity and human-induced unsustainable water use.
• Provided a spatially explicit method to identify and classify areas of distinct ecohydrological coupling, including human-induced unsustainability, offering actionable insights for sustainable water management and policy interventions.

Funding

• National Natural Science Foundation of China (Nos. 42422403; 42504006)

Citation

@article{He2025threedimensional,
  author = {He, Qing and Fok, Hok Sum and Zhou, Hao and Ferreira, Vagner G. and Sun, Yilin},
  title = {A three-dimensional Budyko framework with terrestrial water storage dynamics: mechanistic modeling and diagnostic ecohydrological applications across global basins},
  journal = {Ecological Indicators},
  year = {2025},
  doi = {10.1016/j.ecolind.2025.114357},
  url = {https://doi.org/10.1016/j.ecolind.2025.114357}
}