Some operating characteristics of a rapid response tensiometer system

Watson, K. K.

doi:10.1029/wr001i004p00577

Cited by 36 publications

(13 citation statements)

References 4 publications

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“…This conveys the double advantage of avoiding correction methods for a hydrostatic capillary pressure distribution required in a conventional retention cell [e.g., Jalbert and Dane , 2001], while simultaneously providing a known gradient to the nonwetting fluid for the determination of k rN . Sequential steady state flow conditions (i.e., constant P C and constant NWP flux for each established S W ) were achieved, in contrast to the published method, by fixing the wetting phase saturation at each step and monitoring the wetting phase pressures as they progress to equilibrium [ Watson , 1965]: a process which occurs in hours, rather than the converse which can take days.…”

Section: Methodsmentioning

confidence: 99%

Capillary pressure characteristics necessary for simulating DNAPL infiltration, redistribution, and immobilization in saturated porous media

Gerhard

Kueper

2003

Water Resources Research

104

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[1] This study presents a capillary-pressure saturation (P C -S) constitutive model that incorporates the capillary phenomena necessary for simulating the spatial distribution of nonwetting fluid migrating in a saturated porous medium. To develop a model validation data set, a sequence of dense, nonaqueous phase liquid (DNAPL) pools were emplaced, under alternating drainage and imbibition conditions, in a one-dimensional, 1 m tall, saturated sand pack. A light transmission/image analysis system successfully distinguished between connected-phase and residual nonwetting fluid in the apparatus, thereby permitting the accurate measurement of DNAPL pool heights. These heights are found to depend on the nonzero capillary pressure across the fluid-fluid interface at the top of the pool. The terminal pressure is demonstrated to be the minimum sustainable capillary pressure in connected-phase nonwetting fluid experiencing imbibition, below which residual is formed. Additional bench-scale experiments demonstrate that a nonwetting phase pool will penetrate an underlying capillary barrier when the entry pressure is exceeded and that the resulting infiltration will terminate when the capillary pressure at the barrier reduces to the terminal pressure. At the macroscopic scale the terminal pressure corresponds to the extinction saturation (i.e., zero nonwetting phase flow) at the inflection point on the imbibition P C -S curve. A ratio of terminal to entry pressure of approximately 0.6 is found to apply at both bench and macroscopic scales and to be independent of porous media and fluid properties. The developed P C -S constitutive model, which extends the Brooks-Corey function to incorporate the terminal pressure, successfully predicted the behavior observed in the laboratory experiments. Constitutive models that do not incorporate both an entry and a terminal pressure, such as those based upon the standard van Genuchten function, are demonstrated to be unable to predict the observed equilibrium DNAPL pool heights in homogeneous media or above capillary barriers.

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Section: Methodsmentioning

confidence: 99%

Capillary pressure characteristics necessary for simulating DNAPL infiltration, redistribution, and immobilization in saturated porous media

Gerhard

Kueper

2003

Water Resources Research

104

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“…Details of the system installed at the study site, together with associated field and laboratory tests, are fully reported in Anderson & Kneale (1980a) and Watson (1965). Twenty-two tensiometers were installed at various depths down to 2 m with a de-airing line terminating at the ground surface immediately above each tensiometer location.…”

Section: Pore Pressure Monitoringmentioning

confidence: 99%

The influence of shrinkage cracks on pore-water pressures within a clay embankment

Anderson

Hubbard

Kneale

1982

QJEGH

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For slope stability estimations, the soil pore-water conditions need to be accurately specified. The influence of cracks in clay was previously observed significantly to modify soil water response. In this study shrinkage cracks were monitored in a clay embankment where the soil water response to precipitation had been shown to be more rapid than the clay micro-permeability would predict. The cracks were shown to increase the hydraulic conductivity of the clay at all times of the year and to be the cause of the rapid soil water potential responses monitored. X-ray examinations of closed crack sites indicated that fractures at these sites formerly extended to greater depths.

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“…Ideally, the redistribution of water within soil profiles should be assessed by measuring not only water contents but soil water pressures, thereby critically examining the hysteretic nature of the 0 versus p relation coupled with calculations of capillary conductivity. In the laboratory, the gamma radiation absorption method for measuring soil water and the recently developed pressure transducer technique [Watson, 1965] for instantaneously measuring soil water pressure distributions would allow the necessary data for computer solutions. The role of hysteresis under field conditions could be established by examining water content chan•es in situ.…”

Section: When a Continuous Air Phase Exists Within The Soil The Succmentioning

confidence: 99%

Redistribution of soil water after infiltration

Biswas¹,

Nielsen²,

Biggar³

1966

Water Resources Research

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The redistribution of soil water after the cessation of infiltration in three agricultural soils was analyzed experimentally in the laboratory. It was found that the rate of redistribution within the soil profiles depended upon the initial depth of wetting and the soil water content‐soil water pressure‐capillary conductivity relations. The results are discussed in relation to measured and predicted profiles of inert porous mediums. (Key words: Infiltration;irrigation; soft water)

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Some operating characteristics of a rapid response tensiometer system

Cited by 36 publications

References 4 publications

Capillary pressure characteristics necessary for simulating DNAPL infiltration, redistribution, and immobilization in saturated porous media

Capillary pressure characteristics necessary for simulating DNAPL infiltration, redistribution, and immobilization in saturated porous media

The influence of shrinkage cracks on pore-water pressures within a clay embankment

Redistribution of soil water after infiltration

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