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Abstract The heat transfer and water retention in soils, governed by soil thermal conductivity (λ) and soil water retention curve (SWRC), are coupled. Soil water content (θ) significantly affects λ. Several models have been developed to describe λ(θ) relationships for unsaturated soils. Ghanbarian and Daigle presented a percolation‐based effective‐medium approximation (P‐EMA) for λ(θ) with two parameters: scaling exponent (ts) and critical water content (θc). In this study, we explored the new insights into the correlation between soil thermal conductivity and water retention using the P‐EMA and van Genuchten models. The θcwas strongly correlated to selected soil hydraulic and physical properties, such as water contents at wilting point (θpwp), inflection point (θi), and hydraulic continuity (θhc) determined from measured SWRCs for a 23‐soil calibration dataset. The established relationships were then evaluated on a seven‐soil validation dataset to estimate θc. Results confirmed their robustness with root mean square error ranging from 0.011 to 0.015 cm3cm−3, MAE ranging from 0.008 to 0.013 cm3cm−3, andR2of 0.98. Further discussion investigated the underlying mechanism for the correlation between θcwith θhcwhich dominate both heat transfer and water flow. More importantly, this study revealed the possibility to further investigate the general relationship between λ(θ) and SWRC data in the future.
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This content will become publicly available on January 1, 2026
Modeling compaction effects on soil water retention across the full moisture range: Calibration and validation
Abstract Soil compaction leads to an increase in bulk density () and results in a shift in pore‐size distribution toward smaller pores. These changes alter the soil hydraulic properties (SHPs), that is, the water retention curve and the hydraulic conductivity curve. Most existing models that address the impact of changes in on SHP have been confined to SHP models that consider only capillary water, neglecting water stored and transmitted within adsorbed films (noncapillary water). Recently, a new prediction model was developed that combines the Peters–Durner–Iden (PDI) SHP model system, which accounts for capillary and noncapillary water, with a prediction scheme for compaction effects. However, this new approach has yet to be calibrated and tested against data from soils with varying textures. The objective of this study was to calibrate and evaluate the new water retention model using a comprehensive dataset from the literature. Two different variants, which vary in the number of degrees of freedom have been tested. Remarkably, the variant with only one adjustable parameter, the one that shifts the pore‐size distribution by scaling the pressure head, was sufficient to accurately describe the data. All other parameters can either be fixed at the reference value or scaled based on straightforward physical reasoning. The model achieved low calibration errors (median root mean square error [RMSE]: 0.013; median mean error [ME]: 0.0014) and performed satisfactorily in validation (median RMSE: 0.025; median ME: −0.014). Based on our results, we hypothesize that the scaling approach is independent of the capillary saturation function and that this method might be applied to other models within the PDI system without new calibration.
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- Award ID(s):
- 2037504
- PAR ID:
- 10644082
- Publisher / Repository:
- Vadose Zone Journal
- Date Published:
- Journal Name:
- Vadose Zone Journal
- Volume:
- 24
- Issue:
- 1
- ISSN:
- 1539-1663
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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