Effect of Soil Properties on Unsaturated Hydraulic Conductivity Pore‐Interaction Factors

Schuh, W. M.; Cline, R. L.

doi:10.2136/sssaj1990.03615995005400060001x

Cited by 58 publications

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“…A number of researchers have found that the parameter L can be negative (e.g., Schuh and Cline 1990;Kosugi 1999;de Vos et al 1999;Schaap and Leij 2000).…”

Section: Resultsmentioning

confidence: 99%

Vadose Zone Transport Field Study: Summary Report

Ward¹,

Conrad²,

Daily³

et al. 2006

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SummaryA series of field studies were conducted at the Hanford Site, near Richland, Washington, from FY 2000 through FY 2003 at two different locations to develop data sets to test models of flow and transport in the vadose zone. The field studies were also done to investigate advanced monitoring techniques for evaluating flow-and-transport mechanisms and delineating contaminant plumes in the vadose zone at the Hanford Site. The studies were conducted as part of the Groundwater/Vadose Zone Integration Project Science and Technology Project, now known as the Remediation and Closure Science Project, managed by the Pacific Northwest National Laboratory (PNNL) and supported by the U.S. Department of Energy, Richland Operations Office. This report summarizes the key findings from the field studies and demonstrates how data collected from these studies are being used to improve conceptual models and develop numerical models of flow and transport in Hanford's vadose zone. Results from the field studies and associated analysis have appeared in more than 46 publications generated over the past 4 years. These publications include test plans and status reports in addition to numerous technical notes and papers.Two major field campaigns were performed, one at a well injection test site and a second at a clastic dike test site. Both field studies have resulted in field-scale transport parameters for Hanford conditions, which are useful for improving predictions of subsurface flow and transport at the Hanford Site. In addition, advanced geophysical methods, including high resolution electrical resistivity measurements, were successfully tested and are now being deployed at Hanford for subsurface investigations and tank retrieval detection. The most useful information gained from these studies has been a better understanding of flow and transport in the vadose zone, and this has been specifically related to the impact of small-scale stratigraphic features (e.g., sediment layering) on water flow and contaminant transport. Conceptual models have been developed that take into account the lateral spreading of water and contaminants observed in the field studies. Numerical models of unsaturated flow and transport have been revised to account for lateral spreading of subsurface contaminant plumes.The key results from these studies include: 1) Greater understanding of the complexity of plume migration in the vadose zone at Hanford. Finescale geologic heterogeneities, including grain fabric and lamination, were observed to have a strong effect on the large-scale behavior of contaminant plumes, primarily through increased lateral spreading resulting from anisotropy.2) Observations of anion exclusion in Hanford sediments. Anion exclusion is a mechanism by which negatively charged ions are repelled from the surfaces of negatively charged soil particles, thereby increasing their velocity. Thus, the travel time of ions like pertechnetate, the stable form of 99 Tc found in oxidized environments, may decrease over that of unsaturated water f...

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“…A number of researchers have found that the parameter L can be negative (e.g., Schuh and Cline 1990;Kosugi 1999;de Vos et al 1999;Schaap and Leij 2000).…”

Section: Resultsmentioning

confidence: 99%

Vadose Zone Transport Field Study: Summary Report

Ward¹,

Conrad²,

Daily³

et al. 2006

View full text Add to dashboard Cite

show abstract

“…5 by Mualem (1976). Whereas WoÈ sten and van Genuchten (1988) showed that the parameter varies between À16 and more than 2 and the parameter determined by Schuh and Cline (1990) ranged from about À9 to 15, the eect of the parameter value on the scaling result is still unclear.…”

Section: Introductionmentioning

confidence: 97%

Scaling hydraulic properties of forest soils

2000

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Abstract:For the purpose of characterizing spatial variability of soil hydraulic properties on a forested hillslope, ®ve diering scaling methods were examined using the data set for 30 undisturbed forest soils: scaling of water retention curves, scaling of hydraulic conductivity curves, and simultaneous scaling of both water retention and conductivity curves. For the scaling of conductivity curves and the simultaneous scaling, the soil-poretortuosity parameter in a conductivity model was either ®xed at a constant or treated as a ®tted parameter. Results showed that the set of scaling factors and reference parameters derived by the separate scaling of water retention curves was dierent from that derived by the separate scaling of conductivity curves. Moreover, the separate scaling methods resulted in large estimation errors in either eective saturation or conductivity. Optimizing the tortuosity parameter was eective in improving scaling results. It was concluded that the simultaneous scaling with a ®tted pore-tortuosity parameter was the best among the ®ve methods tested in this study. The obtained scaling factors obeyed the lognormal distribution rather than the normal distribution. The variance of log-transformed scaling factors at the forested hillslope was larger than those at many crop ®elds studied by previous studies. While a spatial dependence of soil hydraulic properties was suggested for the surface layer of the forested hillslope, hydraulic properties of the subsurface layer exhibited large variations even in a small distance.

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“…(2.10), m = 1 -1/n, and l is a pore-connectivity parameter, estimated to be about 0.5 as an average for many soils (Mualem 1976). However, more recent studies (e.g., Schuh and Cline 1990;Yates et al 1992;Schaap and Leij 1998;Zhang et al 2004;Ward et al 2006) suggest that other values of l may represent the hydraulic behavior of many soils equally well or better. In layered soils, saturationdependent anisotropy, which can lead to increased lateral flow in some layers, is best described by a pore connectivity tensor (Zhang et al 2003Raats et al 2004;Ward et al 2006).…”

Section: Hydraulic Conductivitymentioning

confidence: 99%

Geotechnical, Hydrogeologic and Vegetation Data Package for 200-UW-1 Waste Site Engineered Surface Barrier Design

Ward¹

2007

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SummaryFluor Hanford (FH) is designing and assessing the performance of engineered barriers for final closure of U-plant waste sites. The ideal barrier will minimize recharge and plant intrusion into the underlying waste, thereby providing protection for human health and the environment. FH is using the Pacific Northwest National Laboratory (PNNL) Subsurface Transport over Multiple Phases (STOMP) simulator as the primary design optimization tool for simulating surface barrier performance. PNNL is supporting FH barrier design activities. One of PNNL's responsibilities is to provide parameter values for the geotechnical, physical, hydraulic, and thermal properties of the materials comprising the barrier and the structural fill on which it will be constructed as well as parameters to allow simulation of plant effects. This report provides the required data package as well as the technical basis, rationale, and methodology used to obtain the parameter values.Best-estimate values for the hydraulic parameters of the soil and geotechnical materials to be used in the performance assessment analyses of the candidate barriers were developed. Hydraulic properties were directly measured for the Environmental Restoration and Disposal Facility spoil pile soils and the silt loam borrow-source soils. Hydraulic properties for the admixture of silt loam and pea gravel and for the silt admixture and quarry spalls were estimated by adjusting the silt-loam parameters for amount of the coarse material. Geotextile hydraulic properties, which were compiled from data reported in the literature. However, properties of the biointrusion layer were derived from the specified particle-size distribution. A summary of Brooks-Corey and van Genuchten parameters along with saturated hydraulic conductivity are presented for each material.Thermal properties also play a critical role in the water and energy balance. These properties were estimated using pedotransfer functions that take into account the mineralogy and water-retention relationships for the porous materials. Predicted properties compared well with literature values, but were generally higher than those reported for Hanford sediments.Plants play an important role in the function of engineered barriers, and accounting for the effects of plants on barrier performance requires a variety of input parameters. Owing to the number of species that may be used to revegetate engineered barriers, plant parameters were grouped on the basis of plant growth forms, e.g., forbs, grasses, and shrubs. Parameters are provided to allow an evaluation of the effects of canopy structure and color, rooting depth, and growth cycle on energy and water balance and ultimately barrier performance.v

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Effect of Soil Properties on Unsaturated Hydraulic Conductivity Pore‐Interaction Factors

Cited by 58 publications

References 0 publications

Vadose Zone Transport Field Study: Summary Report

Vadose Zone Transport Field Study: Summary Report

Scaling hydraulic properties of forest soils

Geotechnical, Hydrogeologic and Vegetation Data Package for 200-UW-1 Waste Site Engineered Surface Barrier Design

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