Groundwater Flow under a Temperature Gradient

Sato, Kuniaki; Iwasa, Yoshiaki

doi:10.1007/978-4-431-53959-9_4

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…The temperature gradient may significantly affect soil water movement with special nonisothermal conditions (Bach, 1992). In a few studies, the coupled heat and water transfer in the soil can be discovered by inspecting the temperature and other soil physical properties for thermal conductivity (Alrtimi et al, 2016;Evett et al, 2012;Hamdhan and Clarke, 2010;Hiraiwa and Kasubuchi, 2000;Lu et al, 2014;Miyazaki, 2005;Peng et al, 2017;Sato and Iwasa, 2000). We found that thermal conductivity resulting from the latent heat transfer could be separated for those studies.…”

Section: Introductionmentioning

confidence: 89%

Spectral coherence of soil thermal conditions and a stochastic inverse solution for thermal conductivity in the shallow vadose zone of Quaternary gravel formation

Shih

2023

Preprint

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Due to the heterogeneity in the unsaturated or vadose zone, it is challenging to represent the analytical mechanism and actual in-situ water content in the soil layer. However, in the shallow layers, thermal conditions quickly change with surface temperature evolution. It expects that the water content can, more or less, be affected by the in situ heat mechanism. This research, therefore, suggests a novel design to theoretically discover the thermal conditions, such as soil temperature, soil temperature gradient, and heat flux in the shallow Quaternary gravel layer at various depths using spectral analysis of temporal observations. In addition, this research proposes a stochastic inverse solution of thermal conductivity using spectral estimation of soil heat flux and temperature gradient. It suggests that the most apparent periodic fluctuations of the thermal condition are in the diurnal process for 24 hours. The soil temperature gradient and heat flux at 10, 30, 60, and 120 cm depths can catch soil temperature and air temperature changes to some degree in the frequency domain. The thermal conductivity ranges from about 0.41 to 5.44 W/(m°C) for the soil depths from 10 to 120 cm using the inverse spectral solution. Thus, using spectral analysis, assessing the soil layer's thermal conductivity and other thermal conditions becomes feasible and achievable.

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Section: Introductionmentioning

confidence: 89%

Spectral coherence of soil thermal conditions and a stochastic inverse solution for thermal conductivity in the shallow vadose zone of Quaternary gravel formation

Shih

2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The temperature gradient can significantly impact soil water movement, particularly under nonisothermal conditions (Bach, 1992). Several studies have explored the coupled heat and water transfer in the soil by examining temperature and other soil physical properties, specifically thermal conductivity (Alrtimi et al, 2016; Evett et al, 2012; Hamdhan & Clarke, 2010; Hiraiwa & Kasubuchi, 2000; Lu et al, 2014; Miyazaki, 2005; Peng et al, 2017; Sato & Iwasa, 2000). From these studies, it has been observed that thermal conductivity resulting from latent heat transfer can be isolated.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity in a vadose zone: A novel spectral solution and application by the implication of significant coherence of thermal condition in the shallow soil water layer

Shih

2024

Hydrological Processes

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In the context of the heterogeneity in the unsaturated or vadose zone, accurately representing the analytical mechanisms and in‐situ water content within the soil layer poses a significant challenge. Particularly in shallow layers, thermal conditions exhibit rapid changes in response to evolving surface temperatures. This study proposes a hypothesis suggesting that the in situ heat mechanism may notably impact the soil water layer. The research introduces an innovative approach to theoretically uncover thermal conditions, including soil temperature, soil temperature gradients, and heat flux, within the shallow Quaternary gravel layer at various depths through spectral analysis of temporal observations. The study presents a stochastic inverse solution to estimate thermal conductivity by leveraging spectral analysis of soil heat flux and temperature gradients. The findings reveal that thermal conditions exhibit the most prominent periodic fluctuations during the diurnal process over a 24‐hour cycle. The soil temperature gradients and heat flux measurements at depths of 0.1, 0.3, 0.6, and 1.2 m demonstrate their ability to capture changes in soil temperature and air temperature to a certain extent within the frequency domain. Furthermore, the analysis highlights the intrinsic uncertainty and sensitivity of estimating thermal conductivity in heterogeneous soil environments. The wide variability observed in thermal conductivity values, coupled with their dependence on soil type and environmental conditions, underscores the need for careful consideration of these factors in future studies and modeling efforts. Applying the derived inverse spectral solution allows for determining thermal conductivity throughout the soil‐water system across depths ranging from 0.1 to 1.2 m. As a result, this research demonstrates the feasibility and practicality of assessing the thermal conductivity of the soil layer in conjunction with heat flux and temperature gradients through spectral analysis.

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“…The temperature gradient can significantly impact soil water movement, particularly under nonisothermal conditions (Bach, 1992). Several studies have explored the coupled heat and water transfer in the soil by examining temperature and other soil physical properties, specifically thermal conductivity (Alrtimi et al, 2016;Evett et al, 2012;Hamdhan and Clarke, 2010;Hiraiwa and Kasubuchi, 2000;Lu et al, 2014;Miyazaki, 2005;Peng et al, 2017;Sato and Iwasa, 2000). From these studies, it has been observed that thermal conductivity resulting from latent heat transfer can be isolated.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity in a vadose zone: a novel spectral solution and application by the implication of significant coherence of thermal condition in the shallow gravel formation

Shih

2023

Preprint

View full text Add to dashboard Cite

Due to the heterogeneity in the unsaturated or vadose zone, it is challenging to represent the analytical mechanism and actual in-situ water content in the soil layer. However, in the shallow layers, thermal conditions quickly change with surface temperature evolution. It expects that the water content can, more or less, be affected by the in situ heat mechanism. This research, therefore, suggests a novel design to theoretically discover the thermal conditions, such as soil temperature, soil temperature gradient, and heat flux in the shallow Quaternary gravel layer at various depths using spectral analysis of temporal observations. This research primarily proposes a stochastic inverse solution for estimating thermal conductivity using spectral analysis of soil heat flux and temperature gradient. It suggests that the thermal condition exhibits the most periodic fluctuations during the diurnal process over a 24-hour period. The soil temperature gradient and heat flux at depths of 10, 30, 60, and 120 (cm) can capture changes in soil temperature and air temperature to a certain extent in the frequency domain. The thermal conductivity within the soil-water system is determined across soil depths ranging from 10 to 120 cm using the derived inverse spectral solution. Consequently, the utilization of spectral analysis makes it feasible and attainable to assess the thermal conductivity of the soil layer in conjunction with the heat flux and temperature gradient.

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Groundwater Flow under a Temperature Gradient

Cited by 4 publications

References 4 publications

Spectral coherence of soil thermal conditions and a stochastic inverse solution for thermal conductivity in the shallow vadose zone of Quaternary gravel formation

Spectral coherence of soil thermal conditions and a stochastic inverse solution for thermal conductivity in the shallow vadose zone of Quaternary gravel formation

Thermal conductivity in a vadose zone: A novel spectral solution and application by the implication of significant coherence of thermal condition in the shallow soil water layer

Thermal conductivity in a vadose zone: a novel spectral solution and application by the implication of significant coherence of thermal condition in the shallow gravel formation

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