Measurement of fluid contents and wetting front profiles by real-time neutron radiography

Deinert, Mark; Parlange, Jean‐Yves; Steenhuis, Tammo S.; Throop, J. A.; Ünlü, Kenan; Cady, K.B.

doi:10.1016/j.jhydrol.2003.11.018

Cited by 53 publications

(31 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent exceptions are the works by Solymar et al (2003) and Deinert et al (2004), demonstrating NCT application to estimate spatial distribution of water content in rock and soil, respectively. Some studies have also demonstrated the potential application of neutron radiography to study root water depletion zones and ion uptake mechanisms (Korosi et al, 1999;Furukawa et al, 1999).…”

mentioning

confidence: 99%

Thermal Neutron Computed Tomography of Soil Water and Plant Roots

Tumlinson¹,

Liu²,

Silk

et al. 2008

Soil Science Soc of Amer J

View full text Add to dashboard Cite

Neutron radiography is a noninvasive imaging technique that measures the attenuation of thermal neutrons, as is done with x‐ray and γ‐ray radiography, to characterize the internal composition of materials. Neutron and x‐ray imaging are complementary techniques, with neutron imaging especially well suited for materials containing H atoms and other low‐atomic‐weight attenuating materials. Although neutron computed tomography (NCT) techniques are routinely used in engineering, relatively little is known about their application to soils. We developed new techniques that use thermal neutron attenuation to measure the spatial and temporal distribution of water in soils and near roots at near 0.5‐mm spatial resolution or higher. The neutron source was a Mark II Triga Reactor at McClellan Nuclear Radiation Center in Sacramento, CA. After calibration using both deuterated and regular water, the effects of beam hardening and neutron scattering could be corrected for, provided that the total path length for a soil–water mixture does not exceed 1.0 cm, limiting soil sample thickness to about 2.5 cm. Using regular water, for a wide range of soil water content values, experiments demonstrated that NCT is sensitive to small changes in soil volumetric water content, allowing estimation of the spatial distribution of soil water, roots, and root water uptake. Although the spatial resolution of the applied NCT system was 80 μm, an error analysis showed that the averaging measurement volume should be not less than about 0.5 mm for the uncertainty in volumetric water content to be minimized to near 0.01 m3 m−3 A single root water uptake experiment with a corn (Zea mays L.) seedling demonstrated the successful application of NCT, with images showing spatially variable soil water content gradients in the rhizosphere and bulk soil.

show abstract

mentioning

confidence: 99%

Thermal Neutron Computed Tomography of Soil Water and Plant Roots

Tumlinson¹,

Liu²,

Silk

et al. 2008

Soil Science Soc of Amer J

View full text Add to dashboard Cite

show abstract

“…The scattered neutrons smooth the distribution of the brightness over the cylinder image [15,16,18,1921].…”

Section: Discussionmentioning

confidence: 99%

“…For these systems the traditional division of drying into three main periods, named constant rate (CRP), rst and second falling rate periods (FRP) according to the time behavior of rate of mass decrease of drying specimen remains valid [15]. The CRP is determined by the evaporation rate from the sample surface and eciency of capillary forces driving the water to the sample surface from the water lled pores.…”

Section: Introductionmentioning

confidence: 99%

Application of Statistical Image Analysis in Quantification of Neutron Radiography Images of Drying

et al. 2012

View full text Add to dashboard Cite

The statistical approach to the thermal neutron radiography picture analysis is applied to evaluation of the experimental results obtained for drying of rectangular and cylindrical samples of granulated and rigid porous materials. We have shown that the time dependence of the standard deviation of image brightness reects the appearance and motion of the drying front observed during second period of the drying process. The results are discussed within a simple two-region model of the drying sample image.

show abstract

“…DiCarlo et al (1997) presented a technique which used synchrotron X-rays from the Cornell High Energy Synchrotron Source to measure three-phase fluid saturation on the time scale of seconds. Deinert et al (2004) presented a method for using real-time neutron radiography to measure rapidly changing moisture profiles in porous media. In an interesting study, Wells et al (2003) used needle penetrometer to measure the depth of the wetting front along a single transect of the soil, immediately after each rainstorm.…”

Section: Introductionmentioning

confidence: 99%

On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Nakagawa

Saito

Berndtsson

2012

Hydrological Research Letters

View full text Add to dashboard Cite

Abstract:Soil hydraulic properties in field scale porous media are distributed with large spatial heterogeneity. Thus, detailed understanding of micro-physical properties leading to macro-scale heterogeneity is important for generalizing purposes in modeling. Hysteretic water retention properties greatly affect solute transport under unsaturated condition. In this study, laboratory infiltration experiments were carried out to investigate the importance of hysteresis in numerical modeling of water flow under heterogeneous distribution of hydraulic conductivity. Soil water content was observed by time domain reflectometry using small printed circuit board probes (PCBP). The PCBP observations were compared to results from numerical simulations involving saturatedunsaturated seepage analysis and two-phase flow with/ without hysteresis effects. Observations were compared to both uniform and heterogeneous parameter modeling. Differences between unsaturated-saturated and two-phase flow were quite small in the numerical results for soil water content. The uniform parameter model, however, could not properly reproduce experimental water content change. The numerical results of water content change including hysteresis matched better observations for the unsaturatedsaturated and two-phase flow cases. Results displayed that it is important to take heterogeneity and hysteresis into consideration in the numerical modeling in both two-phase and saturated-unsaturated flow analysis.

show abstract

Measurement of fluid contents and wetting front profiles by real-time neutron radiography

Cited by 53 publications

References 17 publications

Thermal Neutron Computed Tomography of Soil Water and Plant Roots

Thermal Neutron Computed Tomography of Soil Water and Plant Roots

Application of Statistical Image Analysis in Quantification of Neutron Radiography Images of Drying

On the importance of hysteresis and heterogeneity in the numerical simulation of unsaturated flow

Contact Info

Product

Resources

About