Estimation of hydraulic conductivities of Yucca Mountain tuffs from sorptivity and water retention measurements

Zimmerman, Robert W.; Bodvarsson, G.S.

doi:10.2172/110771

Cited by 3 publications

(3 citation statements)

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“…Sorptivity S is a measure of the infiltration capacity of the soil by capillarity. In accordance with the description of the hydrostatic equilibrium with the Van Genuchten function (section 2.2.3), we used the following approximate expression with Van Genuchten soil hydraulic parameters to calculate the sorptivity (Zimmerman & Bodvarsson, ):

S = \sqrt{\frac{2 {(1 - 1 / n)}^{4 / 3} K_{s} (θ_{s} - θ_{i})}{α}}

in which

α

[ L −1 ] and

n

are shape parameters of the Van Genuchten water retention model,

θ_{s}

is the saturated soil moisture content,

θ_{r}

is the residual soil moisture content, and

θ_{i}

is the initial soil moisture content at the soil surface. During a simulation, sorptivity and infiltration capacity are calculated for every grid cell in the DEM at the start of each rainfall event, i.e., each time step with rainfall > 0 following a time step in which there is no rainfall.…”

Section: Methodsmentioning

confidence: 99%

Section: Infiltration Schemementioning

confidence: 99%

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Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

Appels

Bogaart

Zee

2017

Water Resources Research

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In winter, saturation excess (SE) ponding is observed regularly in temperate lowland regions. Surface runoff dynamics are controlled by small topographical features that are unaccounted for in hydrological models. To better understand storage and routing effects of small‐scale topography and their interaction with shallow groundwater under SE conditions, we developed a model of reduced complexity to investigate SE runoff generation, emphasizing feedbacks between shallow groundwater dynamics and mesotopography. The dynamic specific yield affected unsaturated zone water storage, causing rapid switches between negative and positive head and a flatter groundwater mound than predicted by analytical agrohydrological models. Accordingly, saturated areas were larger and local groundwater fluxes smaller than predicted, leading to surface runoff generation. Mesotopographic features routed water over larger distances, providing a feedback mechanism that amplified changes to the shape of the groundwater mound. This in turn enhanced runoff generation, but whether it also resulted in runoff events depended on the geometry and location of the depressions. Whereas conditions favorable to runoff generation may abound during winter, these feedbacks profoundly reduce the predictability of SE runoff: statistically identical rainfall series may result in completely different runoff generation. The model results indicate that waterlogged areas in any given rainfall event are larger than those predicted by current analytical groundwater models used for drainage design. This change in the groundwater mound extent has implications for crop growth and damage assessments.

show abstract

S = \sqrt{\frac{2 {(1 - 1 / n)}^{4 / 3} K_{s} (θ_{s} - θ_{i})}{α}}

in which

α

[ L −1 ] and

n

are shape parameters of the Van Genuchten water retention model,

θ_{s}

is the saturated soil moisture content,

θ_{r}

is the residual soil moisture content, and

θ_{i}

Section: Methodsmentioning

confidence: 99%

Section: Infiltration Schemementioning

confidence: 99%

Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

Appels

Bogaart

Zee

2017

Water Resources Research

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show abstract

“…Measurement of sorptivity to characterize soils has long been in practice (Walker and Chong, 1986), but use of the sorptivity approximation to estimate infiltration in fracture-matrix systems is relatively recent (Zimmerman et al, 1993;Foltz et al, 1993;Humphrey et al, 1993;Rasmussen and Evans, 1993;Wang et al, 1993). Rasmussen and Evans (1993) measured infiltration into Apache Leap tuff matrix and analyzed the infiltration using the vertical equivalent of equation (1).…”

Section: Chapter 2: Studies Of Imbibition In Fractured Rocksmentioning

confidence: 99%

The role of fracture coatings on water imbibition into unsaturated tuff from Yucca Mountain

Chekuri¹,

Tyler²,

Fordham³

1995

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Laboratory measurement of water imbibition into low-permeability welded tuff

Persoff

Wang

2001

Journal of Hydrology

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Estimation of hydraulic conductivities of Yucca Mountain tuffs from sorptivity and water retention measurements

Cited by 3 publications

References 20 publications

Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

The role of fracture coatings on water imbibition into unsaturated tuff from Yucca Mountain

Laboratory measurement of water imbibition into low-permeability welded tuff

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