Z. J. Kabala

Duke University

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Todd H. Skaggs

U.S. Salinity Laboratory

Nels Ruud

California Environmental Protection Agency

Markus Egli

University of Zurich

A. G. Hunt

Wright State University

Muhammad Sahimi

University of Southern California

P. C. D. Milly

NOAA Geophysical Fluid Dynamics Laboratory

Boris Faybishenko

Lawrence Berkeley National Laboratory

Behzad Ghanbarian

The University of Texas at Arlington

Garrison Sposito

University of California, Berkeley

Alan E. Williams

University of California, Riverside

Cooperative Institutions

Duke University

University of California, Riverside

University of California, Berkeley

U.S. Salinity Laboratory

University of California System

Wright State University

Lawrence Berkeley National Laboratory

University of Virginia

Oak Ridge National Laboratory

Lawrence Livermore National Laboratory

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Probing soil and aquifer material porosity with nuclear magnetic resonance

Water Resources Research (1993)

Zeina R. Hinedi Z. J. Kabala Todd H. Skaggs Dan Borchardt R. W. K. Lee

Nuclear magnetic resonance relaxation measurements were used to identify different characteristic porosity domains in soil and aquifer materials. The porosity distribution can be inferred from these measurements by a regularization method applicable to any nuclear magnetic resonance (NMR) relaxation, or by an analytic method applicable only to multiexponential relaxations (D. Orazio et al., 1989). The porosity distribution obtained from NMR relaxation measurements strongly depends on the pore shape factor. For the Borden aquifer material, both the regularized and the analytic pore size distribution obtained from NMR relaxation measurements are consistent with those obtained by Ball et al. (1990) using Hg porosimetry and N 2 adsorption. For the Eustis and the Webster soils, the measured porosity domains are qualitatively consistent with those expected based on their respective composition. Our findings suggest that due to the long time required to saturate fine pores, NMR measurements of porosity distribution that are collected at short saturation times are biased toward larger pore sizes.

Porosimetry

Saturation (graph theory)

10.1029/93wr02302

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Citations (42)

Field Hydrogeology, 2nd ed.

Journal of Hydrology (2000)

Z. J. Kabala

10.1016/s0022-1694(00)00258-4

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Citations (6)

Sensitivity Analysis of Infiltration, Exfiltration, and Drainage in Unsaturated Miller‐Similar Porous Media

Water Resources Research (1991)

Z. J. Kabala P. C. D. Milly

The effects of soil heterogeneity on the transport of moisture in the unsaturated zone are studied by means of functional sensitivities, which are more suitable than elementary (or conventional) sensitivities for analyzing continuous systems. The earlier described algorithm is applied to three problems, drainage, infiltration, and exfiltration, for two Miller‐similar soils (a randomly generated heterogeneous Yolo light clay and a homogeneous one). It reveals the difference between drainage, on the one hand, and both infiltration and exfiltration on the other. The scaled flux sensitivity profiles, i.e., the functional derivatives of fluxes with respect to Miller‐similarity parameter λ( x ), are flat for drainage, demonstrating that drainage is equally sensitive to changes in λ( x ) at all points of the profile and hence that the similarity parameter has to be modeled well in the whole soil column. Analogous sensitivity profiles for infiltration and exfiltration problems show, significant delay in propagation of functional sensitivities in the soil column (with respect to the moisture front), allowing thus for less stringent modeling of the similarity parameter for the bottom of the column. Infiltration problems seem to be most difficult to deal with, because they are most sensitive to the similarity parameter.

Infiltration (HVAC)

10.1029/91wr01869

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Citations (4)

Rapidly Pulsed Pumping Accelerates Remediation in A Vertical Circulation Well Model

Water (2018)

David M. Kahler Z. J. Kabala

One factor that slows groundwater remediation is the sequestration of contaminant in dead-end pores, that is, pores that are not flushed through by flow through the aquifer. Furthermore, rebound of apparently remediated aquifers can occur as a result of the eventual release of the contaminant trapped in these dead-end pores. Since the operational costs generally outweigh the capital costs of a remediation project, reduction of the duration of treatment should reduce the overall cost of the average remediation. It has been shown that a rapidly pulsed flow can increase the mixing between dead-end and well-connected pores through computational fluid dynamics models with idealized pore geometry and column tests. A rapidly pulsed flow induces a deep sweep upon a sudden increase in velocity and a vortex ejection upon a sudden decrease in velocity that substantially accelerates the remediation of contaminant from these dead-end pores. To examine rapidly pulsed pumping in a more realistic configuration, a model vertical circulation well was constructed. The porous medium was well-sorted crushed glass to minimize sorption. Removal of a fluorescent dye, which represents a dissolved contaminant, under a rapidly pulsed flow was compared to a steady flow. The modeled well revealed accelerated removal of dissolved contaminants under a rapidly pulsed flow.

Groundwater Remediation

Clogging

10.3390/w10101423

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Citations (17)

The dipole flow test: A new single‐borehole test for aquifer characterization

Water Resources Research (1993)

Z. J. Kabala

A new single‐borehole measurement technique for confined aquifers, the dipole flow test, yields the vertical distributions of the horizontal hydraulic conductivity, the vertical hydraulic conductivity, and the specific storativity when applied to different borehole intervals. The test utilizes straddle packers to isolate two chambers in the borehole, pressure transducers to monitor drawdown in them, and a small pump to create a dipole flow pattern in the aquifer by pumping water at a constant rate from the aquifer into one chamber, transferring it within the well to the next chamber, and finally injecting it back to the aquifer. A mathematical model describing the drawdown in each chamber is derived for the transient as well as the steady state cases. The aquifer parameters may be estimated from data produced by the dipole flow test alone or in conjunction with conventional pumping tests. The dipole flow regime reaches a steady state relatively quickly, especially in well permeable aquifers. A robust computational methodology for estimating the aquifer parameters, suitable for automatization, is based on the Newton‐Raphson algorithm applied to a system of up to three nonlinear equations, each describing the well drawdown at a different judiciously chosen time. Due to the relatively small drawdown it invokes, the dipole flow test may be applicable to unconfined aquifers as well.

Aquifer test

Drawdown (hydrology)

Slug test

Aquifer properties

Specific storage

10.1029/92wr01820

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Citations (108)

Natural and Anthropogenic Nitrate Contamination of Groundwater in a Rural Community, California

Environmental Science & Technology (1998)

Alan E. Williams L. J. Lund J.A. Johnson Z. J. Kabala

Contamination of small basins impacts the quality of groundwater resources and the health of residents dependent on local, limited water supplies. Understanding contaminant sources is crucial not only to planning mitigation and cleanup but also to the rural community, who must participate in any scientific or regulatory effort. Groundwaters, rock, and soil samples representative of the Sierra Pelona Valley in an arid, "Mediterranean" climate region of southern California indicate significant anthropogenic nitrate contamination. Groundwater nitrate from diverse sources can be differentiated on the basis of chemical and isotopic compositions. Samples analyzed for dissolved or leachable ion concentrations as well as δ15N provide both chemical and isotopic signatures that distinguish between potential contaminant sources. Data indicate a predominance of anthropogenic, organic human and/or animal waste and decay of irrigation-enhanced vegetation. Natural nitrate sources are minor but include low concentration soil nitrate from decay of sparse, natural vegetation and nitrogen-bearing rock units. Anthropogenic sources almost certainly contribute more than half of the nitrate found in the basin as a whole and provide the dominant source in the ≈40% of water wells that routinely or occasionally exceed the nitrate-N public drinking water standard concentration of 10 mg/L.

10.1021/es970393a

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Citations (72)

Comment on “Minimum relative entropy inversion: Theory and application to recovering the release history of a groundwater contaminant” by Allan D. Woodbury and Tadeusz J. Ulrych

Water Resources Research (1998)

Z. J. Kabala Todd H. Skaggs

10.1029/98wr01337

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Citations (18)

Comment on: An exposition of the distribution function used in proving the averaging theorems for multiphase flow

Advances in Water Resources (1984)

Z. J. Kabala