790 results
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Journal Article
Efficient Bayesian Inverse Modeling of Water Infiltration in Layered Soils
Modeling water movement in heterogeneous soils, e.g., layered soils, is an essential but challenging task that requires accurate estimation of multiple sets of soil hydraulic parameters. Markov chain Monte Carlo (MCMC) is a popular but computationally expensive method for parameter estimation. An…
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Journal Article
Numerical Evaluation of Unsaturated-Zone Flow and Transport Pathways at Rainier Mesa, Nevada
Sixty-one underground nuclear tests were conducted at Rainier Mesa at the Nevada National Security Site between 1957 and 1992. The mesa includes the highest-elevation areas at the Nevada National Security Site and experiences some of the highest estimated infiltration rates. Perched water is…
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Journal Article
The Effect of Dynamic Capillarity in Modeling Saturation Overshoot during Infiltration
Gravity-driven fingering has been observed during downward infiltration of water into dry sand. Moreover, the water saturation profile within each finger is non-monotonic, with a saturation overshoot at the finger tip. As reported in the literature, these effects can be simulated by an extended…
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Journal Article
Bound Water, Phase Configuration, and Dielectric Damping Effects on TDR-Measured Apparent Permittivity
The time domain reflectometry (TDR) method measures the soil apparent permittivity (), which is the basis for estimation of soil volumetric water content (θ) via an empirical calibration equation or dielectric mixing model. The relationship between and θ [i.e., (θ)] in soils with significant…
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Journal Article
Capacity and Distribution of Water Stored in the Vadose Zone of the Chinese Loess Plateau
Water stored in the vadose (unsaturated) zone provides the majority of water required by plants and buffers water resources; thus, it is central to understanding ecological and hydrological processes in the Chinese Loess Plateau (CLP) with its thick loess deposits. We used multisource data on soil…
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Journal Article
Measurement of Unirrigated Turfgrass Evapotranspiration Rate in the Red River Valley
Turfgrass actual evapotranspiration (ET) measurements are critical for water management and irrigation scheduling. With no historical ET measurements in eastern North Dakota, turfgrass ET rates were measured with the residual method using eddy covariance instrumentation and two arrays of soil…
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Journal Article
Local Solute Sinks and Sources Cause Erroneous Dispersion Fluxes in Transport Simulations with the Convection–Dispersion Equation
The convection–dispersion equation (CDE) is the most widely used model for simulating the transport of dissolved substances in porous media. The dispersion term in the CDE lumps molecular diffusion and hydromechanical dispersion into an effective diffusive solute flux. This is possible by…
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Journal Article
New Sensor Technology for Field-Scale Quantification of Carbon Dioxide in Soil
Biological activity in soil causes fluxes of O into and CO out of the soil with significant global relevance. Hence, the dynamics of CO concentrations in soil can be used as an indicator for biological activity. However, there is an enormous spatial and temporal variability in soil respiration…
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Journal Article
Augmented Brunauer–Emmett–Teller Equation for Water Adsorption on Soils
An augmented Brunauer–Emmett–Teller (BET) equation was developed for describing water adsorption on soils, overcoming the limitation of the original BET equation for describing only isotherms of materials with a homogeneous adsorption surface. The different physicochemical mechanisms underlying…
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Journal Article
Water Flow in Soils with Heterogeneous Macropore Geometries
Heterogeneous macroporous geometries (HMGs) comprise unevenly distributed macropores with depth. A large variety of macropore distributions produce fast water flow and chemical transport that deviate from uniform flow. We analyzed the measured pressure head and outflow in column experiments with a…
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Journal Article
A Test of Two Spatial Frameworks for Representing Spatial Patterns of Wetness in a Glacial Drift Watershed
In forest ecosystems, soil water availability is an important indicator and driver of biogeochemical transformations, pedogenesis, and surface water–groundwater linkages. Given the importance of soil moisture and shallow groundwater to ecosystem processes, field measurements are critical. We…
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Journal Article
Investigation of Data Assimilation Methods for Soil Parameter Estimation with Different Types of Data
In the past few decades, different data assimilation methods have been proposed to estimate soil parameters. It is not clear whether a straightforward sampling approach is sufficient or whether a linear filter or even an advanced nonlinear filter is needed to interpret the potential information…
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Journal Article
Separation of Soil Macropore Types in Three-Dimensional X-Ray Computed Tomography Images Based on Pore Geometry Characteristics
In structured soils, earthworm burrows, root channels, shrinkage cracks, and interaggregate spaces form complex macropore networks. Depending on the type and morphological properties, each macropore surface type is coated with specific organo-mineral compounds, differently affecting sorption and…
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Journal Article
Determining Millimeter-Scale Maps of Cation Exchange Capacity at Macropore Surfaces in Bt Horizons
During preferential flow in structured soils, solute transport is largely restricted to a complex network of macropores. Clay–organic coatings of macropore surfaces determine soil physicochemical properties relevant for mass transport and carbon and nutrient turnover, such as the cation exchange…
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Journal Article
Comparison of Cation Exchange Capacity Estimated from Vis–NIR Spectral Reflectance Data and a Pedotransfer Function
Knowledge of the cation exchange capacity (CEC) for soils or other porous media is very important for civil engineering and agricultural applications. However, the standard laboratory methods to measure CEC are costly and laborious. The aim of this research was to develop a visible–near-infrared…
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Journal Article
Estimating Near-Saturated Soil Hydraulic Conductivity Based on Its Scale-Dependent Relationships with Soil Properties
Soil hydraulic conductivity near saturation () is affected by various soil properties operating at different spatial scales. Using noise-assisted multivariate empirical mode decomposition (NA-MEMD), our objective was to inspect the scale-dependent interactions between and various soil properties…
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Journal Article
Three-Dimensional Time-Lapse Geoelectrical Monitoring of Water Infiltration in an Experimental Mine Waste Rock Pile
Open-pit mines often generate large quantities of waste rocks that are usually stored in waste rock piles (WRPs). When the waste rocks contain reactive minerals (mainly sulfides), water and air circulation can lead to the generation of contaminated drainage. An experimental WRP was built at the Lac…
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Journal Article
More than Meets the Dye: Evaluating Preferential Flow Paths as Microbial Hotspots
Preferential flow paths have been suggested to function as microbial hotspots. This idea is speculative, based on biomass counts rather than assessments of the activity of the microbial population. In this study we used O–sensitive optodes, or optical sensor devices, to observe O depletion by soil…
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Journal Article
Physically Based Model for Extracting Dual-Permeability Parameters Using Non-Newtonian Fluids
Dual-permeability models simulate flow and transport within soils characterized by preferential (macro) and matrix (micro) pore domains, with each exhibiting distinct hydraulic properties. The lack of suitable methods for determining appropriate and physically based model parameters remains a major…
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Journal Article
Rock Fracture Sorptivity as Related to Aperture Width and Surface Roughness
Fractures in low-porosity rocks can provide conduits for fluid flow. Numerous researchers have investigated fluid flow through fractures under saturated conditions. However, relatively little information exists on spontaneous imbibition in fractures, whereby a wetting fluid displaces a non-wetting…