Ansari et al. (2026) Terrestrial water storage monitoring in Bulgaria using Global Navigation Satellite System (GNSS) displacements and comparison with GLDAS, GLWS and GRACE products

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Identification

• Journal: Environmental Earth Sciences
• Year: 2026
• Date: 2026-08-03
• Authors: Kutubuddin Ansari, Emine Tanır Kayıkçı, Lyubka Pashova
• DOI: 10.1007/s12665-026-13067-0

Research Groups

Not specified in the provided text.

Short Summary

The study estimates Terrestrial Water Storage (TWS) variations in Bulgaria by inverting GNSS vertical displacements into Equivalent Water Height (EWH), finding annual amplitudes typically between 10 and 30 mm.

Objective

• To investigate Terrestrial Water Storage (TWS) variations across Bulgaria using GNSS-derived vertical displacements and evaluate these estimates against independent hydrological and gravimetric datasets.

Study Configuration

• Spatial Scale: National scale (Bulgaria), utilizing 32 GNSS stations.
• Temporal Scale: 2004–2025.

Methodology and Data

• Models used: Singular Spectrum Analysis (SSA), elastic Green's function approach, and Tikhonov regularization.
• Data sources: GNSS vertical displacement time series, Global Land Data Assimilation System (GLDAS)-Noah, Global Land Water Storage (GLWS), and Gravity Recovery and Climate Experiment (GRACE) products.

Main Results

• TWS Amplitudes: Annual variations generally range from 10 to 30 mm, with localized peaks exceeding 40 mm.
• Seasonality: Maximum annual storage typically occurs between June and September; monthly climatology shows peaks in February–April and minima in August–October.
• Comparative Analysis: Strong correlations (up to 0.927) were observed between GLDAS, GLWS, and GRACE datasets, while GNSS-derived estimates showed weaker correlations due to station distribution and non-hydrological deformation.

Contributions

• Demonstrates the utility of GNSS vertical displacements as a complementary tool for monitoring hydrological loading and water storage variability in Bulgaria, supplementing traditional gravimetric and hydrological models.

Funding

Not specified in the provided text.

Citation

@article{Ansari2026Terrestrial,
  author = {Ansari, Kutubuddin and Kayıkçı, Emine Tanır and Pashova, Lyubka},
  title = {Terrestrial water storage monitoring in Bulgaria using Global Navigation Satellite System (GNSS) displacements and comparison with GLDAS, GLWS and GRACE products},
  journal = {Environmental Earth Sciences},
  year = {2026},
  doi = {10.1007/s12665-026-13067-0},
  url = {https://doi.org/10.1007/s12665-026-13067-0}
}