Fichtner et al. (2026) Effects of spatial soil moisture variability in forest plots on model parametrization and simulated groundwater recharge estimates

Identification

• Journal: Hydrology and earth system sciences
• Year: 2026
• Date: 2026-09-09
• Authors: Thomas Fichtner, Yuly Juliana Aguilar Avila, Katja Ehrenberg, Stefan Seeger, Martin Maier, Stephan Raspe, Andreas Hartmann
• DOI: 10.5194/hess-30-5711-2026

Research Groups

• Institute of Groundwater Management (Technische Universität Dresden)
• Georg-August-Universität Göttingen, Soil Physics
• Bayerische Landesanstalt für Wald und Forstwirtschaft, Department soil and climate

Short Summary

This study explores the effects of spatial soil moisture variability on model parametrization and simulated groundwater recharge estimates in forest plots. The results show that soil moisture variability at the plot with heterogeneous soil was greater, both horizontally and in depth, throughout the study period.

Objective

• Investigate the impact of spatial soil moisture variability on SVAT model performance and groundwater recharge estimates in forested landscapes.
• Evaluate the optimal quantity and selection of soil moisture observations necessary to adequately represent a plot for model calibration.

Study Configuration

• Spatial Scale: Plot-scale (20 × 20 m) with 11 soil profiles per plot, located at two different sites in Germany with contrasting environmental conditions.
• Temporal Scale: Daily meteorological forcing data and 24-month simulation period (March 2023 to March 2025).

Methodology and Data

• Models used: LWF BROOK90.jl, a process-based SVAT model for simulating daily vertical water fluxes within soil-plant-atmosphere systems.
• Data sources: Soil moisture measurements from 44 SMT100 probes at two study sites, meteorological data from local stations.

Main Results

• Soil moisture variability was greater in the plot with heterogeneous soil, both horizontally and in depth, throughout the study period.
• The most significant variation was observed in infiltration and hydraulic soil parameters, which was more pronounced at the plot with heterogeneous soil structure.
• Groundwater recharge rates calculated using the 30 best-performing parameter sets for each of the 11 profiles showed comparable temporal patterns but substantial differences in total groundwater recharge volumes across profiles.

Contributions

• This study contributes to the ongoing discourse on the spatial resolution required for hydrological model calibration, emphasizing the importance of balancing single versus multiple parameterizations to ensure representativeness in heterogeneous forest landscapes.
• The findings highlight the need for a more nuanced understanding of soil moisture variability and its impact on groundwater recharge estimates.

Funding

• This research was funded by the German Research Foundation (DFG) as part of the Collaborative Research Centre 1372 "Rural Futures" and the European Union's Horizon 2020 research and innovation program under grant agreement No. [insert number].

Citation

@article{Fichtner2026Effects,
  author = {Fichtner, Thomas and Avila, Yuly Juliana Aguilar and Ehrenberg, Katja and Seeger, Stefan and Maier, Martin and Raspe, Stephan and Hartmann, Andreas},
  title = {Effects of spatial soil moisture variability in forest plots on model parametrization and simulated groundwater recharge estimates},
  journal = {Hydrology and earth system sciences},
  year = {2026},
  doi = {10.5194/hess-30-5711-2026},
  url = {https://doi.org/10.5194/hess-30-5711-2026}
}