Heat as a Tracer for Examining Depth‐Decaying Permeability in Gravel Deposits

Sakata, Yoshitaka

doi:10.1111/gwat.12236

Cited by 9 publications

(7 citation statements)

References 46 publications

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“…This study counted the number of individual 0.1 m cells that were vertically connected in the stochastically generated fields. In this simulation, constant head boundaries of 20 and 19 m were assigned to the upstream and downstream sides of the cube, respectively, resulting in the mean hydraulic gradient of 0.1 (m/m), as the highest value of the water table around the losing section of the river discharge (Sakata, 2014). However, the calculation results of K e were rarely dependent on the head boundary condition (the comparison was omitted due to paper length restriction).…”

Section: Modeling and Analysis Methodsmentioning

confidence: 99%

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Vertical trend analysis of equivalent hydraulic conductivity in alluvial fan gravel deposits considering open void connectivity

Sakata

2019

Hydrological Research Letters

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This study demonstrated groundwater flow simulations to investigate a vertical trend of equivalent hydraulic conductivity of alluvial fan gravel deposits in Sapporo, Japan, considering open void connectivity. Equivalent hydraulic conductivity was defined according to Darcy's Law for a cube of 10 m in size, consisting of one million cells assigned among fully packed (without open voids), loosely packed (with less-connected voids) or very loosely packed (with well-connected voids) deposits. The stochastic generation was performed under each configuration in terms of target depth sections for vertical trend analysis, and horizontal variogram ranges (random, high, and low connectivity, and no open voids) for open void connectivity. The logarithmic average of 100 equivalent hydraulic conductivities was calculated in each configuration, and the vertical trends were determined. The simulation results showed that the equivalent hydraulic conductivity increased when the open void frequency was large in the shallow zone and the connectivity of the open voids was assumed. In particular, the high connectivity assumption was needed to match the in situ trend with a decay exponent of 0.05 m-1. Modeling the vertical trend with such a large decay exponent was essential to obtain realistic solutions of the groundwater flow and transport system in the alluvial fan. KEYWORDS hydraulic conductivity; vertical trend; alluvial fan; gravel deposits; open void connectivity; groundwater flow simulation

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Section: Modeling and Analysis Methodsmentioning

confidence: 99%

“…The previous study also determined the vertical trend of core-scale K with the decay exponent of A = 0.11 m -1 . Such a large decay exponent plays a role of controlling the groundwater flow and transport near the ground in the alluvial fan (Sakata, 2014).…”

Section: Introductionmentioning

confidence: 99%

Vertical trend analysis of equivalent hydraulic conductivity in alluvial fan gravel deposits considering open void connectivity

Sakata

2019

Hydrological Research Letters

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“…In recent years, the depth-decay and anisotropy of hydraulic conductivity has been found to have significant effects on groundwater flow, solute and heat transport, and distribution of groundwater age and residence time in basins Jiang et al, 2010;Gomez and Wilson, 2013;Sakata, 2015;Zlotnik et al, 2011]. Here, we examine how they affect the critical depth of artesian flow conditions and the rate of variation in artesian head with depth.…”

Section: Effect Of the Depth-decay And Anisotropy Of Hydraulic Conducmentioning

confidence: 96%

An analytical study on artesian flow conditions in unconfined‐aquifer drainage basins

Wang

Jiang

Wan

et al. 2015

Water Resources Research

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Although it has been reported that flowing artesian wells could be topographically controlled, there is no quantitative research on artesian flow conditions in unconfined aquifers. In this study, the water table, which has a lower amplitude than the land surface, is damped from the topography and used as the boundary condition to obtain the analytical solution of hydraulic head of a unit basin with a single flow system. The term artesian head is defined to characterize the condition of flowing artesian wells. The zone with positive artesian head is called artesian zone while with negative artesian head is nonartesian zone. The maximum artesian head and the size of artesian zones are found to increase with the damping factor and the anisotropy ratio, and decrease with the ratio of basin width to depth and the depth‐decay exponent of hydraulic conductivity. Moreover, the artesian head increases with depth nearby the valley and decreases with depth near by the divide, and the variation rates are influenced by the decay exponent and the anisotropy ratio. Finally, the distribution of flowing artesian wells and the artesian head measurements in different depths of a borehole in a small catchment in the Ordos Plateau, Northwestern China is used to illustrate the theoretical findings. The change in artesian head with depth was used to estimate the anisotropy ratio and the decay exponent. This study opens up a new door to analyze basin‐scale groundwater flow.

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“…The records of river temperatures near Site 2 until March 2011 were publicly available [18]. The author also measured groundwater temperatures in a borehole at Site 2 from June 2010 [19] to the present. Here, the temperature data between June 2010 to March 2011 were used for the analysis of peak delay in temperatures.…”

Section: Field Experiments Settingmentioning

confidence: 99%

Evaluating Groundwater Flow Effects for Enhancement of Ground-Source Heat Pipes in the Case of the Toyohira River Alluvial Fan, Japan

Sakata

Chishimba

Mochizuki³

et al. 2021

Hydrology

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The purpose of this study was to evaluate the potential enhancement of ground-source heat pipes by groundwater advection at two sites within an alluvial fan of Toyohira River, Sapporo. Two sites were selected: one in the fan toe, for negligible groundwater flow (Site 1), and the other in the apex for fast flows, the latter characterized by a specific discharge of 1.0 m/d from the losing river (Site 2). The evaporator section(s) of a single (double) heat pipe(s) was installed in a borehole at each site; the condenser section(s) on the ground was placed inside cooled brine at a set temperature, resulting in heat extraction under steady conditions. The single heat pipe experiments showed that the heat extraction rates ranged between 0.23 and 0.79 kW and were not clearly different at the two sites, considering some uncertainty. For double heat pipes, the heat extraction rates were unchanged at Site 1, but were about 146% higher at Site 2 compared to the single tests, due to groundwater advection. This study revealed that the number of ground-source heat pipes required could be reduced from three to two in areas near Site 2.

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Heat as a Tracer for Examining Depth‐Decaying Permeability in Gravel Deposits

Cited by 9 publications

References 46 publications

Vertical trend analysis of equivalent hydraulic conductivity in alluvial fan gravel deposits considering open void connectivity

Vertical trend analysis of equivalent hydraulic conductivity in alluvial fan gravel deposits considering open void connectivity

An analytical study on artesian flow conditions in unconfined‐aquifer drainage basins

Evaluating Groundwater Flow Effects for Enhancement of Ground-Source Heat Pipes in the Case of the Toyohira River Alluvial Fan, Japan

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