Engdahl (2025) Impacts of Uncertain Permeability Fields on the Transient Hydrologic Response in Coupled Surface‐Subsurface Simulations of a Headwaters Catchment

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Identification

• Journal: Water Resources Research
• Year: 2025
• Date: 2025-10-01
• Authors: Nicholas B. Engdahl
• DOI: 10.1029/2025wr040668

Research Groups

[Information not available in the provided abstract.]

Short Summary

This study assesses the confidence of an Integrated Hydrologic Model (IHM) simulation of a first-order basin under transient conditions, using an ensemble of 250 permeability realizations and varying recharge signals. It finds high confidence in surface water simulations but lower confidence in groundwater, with groundwater uncertainty decreasing over time after a recharge increase, and determines the ensemble sizes needed for convergence.

Objective

• To assess the confidence of an Integrated Hydrologic Model (IHM) representation of a first-order basin under transient conditions, considering uncertainty from an ensemble of permeability realizations and different recharge forcing signals.

Study Configuration

• Spatial Scale: A first-order basin in central Idaho, USA.
• Temporal Scale: Transient conditions, assessing dynamic changes over time following recharge events.

Methodology and Data

• Models used: Integrated Hydrologic Models (IHMs).
• Data sources: Ensemble of 250 permeability realizations; three different recharge forcing signals (used as model inputs).

Main Results

• Surface water simulations exhibit high confidence across all permeability realizations.
• The groundwater system and its changes are simulated with lower confidence.
• Uncertainty in changes to the groundwater system decreases with time following an increase in recharge.
• Groundwater simulations require larger ensembles for convergence compared to surface flows.
• The ensemble sizes necessary for capturing expected behaviors and their range of variability were smaller than initially expected.

Contributions

• Extends previous uncertainty quantification (UQ) work on Integrated Hydrologic Models (IHMs) from steady-state to transient conditions.
• Quantifies confidence levels for surface water versus groundwater responses to permeability uncertainty and varying recharge.
• Provides insights into the temporal evolution of groundwater uncertainty following recharge events.
• Determines the necessary ensemble sizes for capturing IHM behaviors under uncertainty, offering practical guidance for future UQ studies.

Funding

[Information not available in the provided abstract.]

Citation

@article{Engdahl2025Impacts,
  author = {Engdahl, Nicholas B.},
  title = {Impacts of Uncertain Permeability Fields on the Transient Hydrologic Response in Coupled Surface‐Subsurface Simulations of a Headwaters Catchment},
  journal = {Water Resources Research},
  year = {2025},
  doi = {10.1029/2025wr040668},
  url = {https://doi.org/10.1029/2025wr040668}
}