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  • 1
    Language: English
    In: Journal of Hydrology, 2011, Vol.402(3), pp.261-273
    Description: ► Numerical modelling captured transition in dispersiveness of observed up-coning. ► General head boundary conditions were needed to simulate the sand-tank inflow ports. ► Late-time well salinities were primarily controlled by the plume width. In this study, previous interpretations of the density-dependent flow and transport processes induced by pumping freshwater above denser saltwater in four laboratory sand-tank experiments are extended using numerical modelling. The numerical model captured the transition in dispersiveness of up-coning plumes observed in the laboratory (i.e. highly dispersive at early times tending to sharp-interfaces after saltwater reaches the well). This demonstrates the applicability of the velocity-dependent dispersion of the modelling code. In all four experiments, head-dependent flux boundary conditions were used to simulate the sand-tank side boundary conditions. The experimentally derived boundary conductance values indicate non-linear variations in the resistance to flow through side inflow ports between the different experiments. Nonetheless, linear boundary head-inflow relationships adequately reproduced laboratory up-coning. The numerical model was able to reproduce the laboratory results within a reasonable level of accuracy and with minimal calibration of model parameters for three of the four experiments. This serves to validate those particular laboratory observations. The “double-peak” up-coning observed late in the fourth laboratory experiment was not reproduced by the model. Further analysis considering adsorption of the Rhodamine tracer is suggested to explore the cause of this effect. Numerical modelling results were compared to an existing sharp-interface analytical solution, which corresponded well with the numerical modelling results for early stages of the four up-coning experiments, despite the dominant influence of dispersion at early times.
    Keywords: Up-Coning ; Laboratory Experiment ; Numerical Model ; Dispersivity ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 2
    Language: English
    In: Journal of Hydrology, Jan 11, 2012, Vol.414-415, p.503(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2011.11.028 Byline: Jessica E. Liggett, Adrian D. Werner, Craig T. Simmons Keywords: Surface-subsurface interaction; Integrated modelling; Overland flow; Coupling length; HydroGeoSphere Abstract: a* Influence of first-order exchange coefficient (FOEC) on exchange flux and overland flow is explored. a* Guidance on FOEC values is provided through systematic analysis of coupled 1D simulations. a* Lower coupling length (le) values are needed for Hortonian conditions or in low permeability soils. a* Top-down saturation occurs under Hortonian conditions when le a[c]1/2 total obstruction height (Hs). a* Hs (when composed of sub-grid depression storage only) is a useful initial estimate of le. Author Affiliation: National Centre for Groundwater Research & Training, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia Article History: Received 20 May 2011; Revised 10 November 2011; Accepted 11 November 2011 Article Note: (miscellaneous) This manuscript was handled by Geoff Syme, Editor-in-Chief
    Keywords: Depression (Mood disorder) -- Analysis ; Permeability -- Analysis ; Groundwater -- Analysis
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Hydrology, Jan 11, 2012, Vol.414-415, p.503(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2011.11.028 Byline: Jessica E. Liggett, Adrian D. Werner, Craig T. Simmons Keywords: Surface-subsurface interaction; Integrated modelling; Overland flow; Coupling length; HydroGeoSphere Abstract: Presently, there is little guidance for model users on the selection of the first-order exchange coefficient (FOEC; or "conductance") commonly used in simulating surface-subsurface interactions (e.g. infiltration). In this study, relationships between the FOEC and surface-subsurface exchange flux, surface-subsurface head difference and time to initiate overland flow are systematically explored using 1D soil column simulations with the fully integrated code HydroGeoSphere. Numerical experiments adopt five different hydrological scenarios and nine different soil profiles. Results converge on the more accurate, but sometimes more computationally intensive, continuity of pressure (COP) coupling approach as the coupling length (l.sub.e) parameter within the FOEC is decreased (i.e. FOEC increased). Threshold l.sub.e values that produce results converged on the COP approach vary considerably with hydrological scenario, soil type and total obstruction height (H.sub.s ; accounting for sub-grid depression storage), with most threshold l.sub.e values a[c]1/210.sup.-2 m. Lower l.sub.e values are required for infiltration under Hortonian conditions, under non-Hortonian conditions in lower permeability soils, and to capture timing of initiation of overland flow. The condition l.sub.e H.sub.s precludes top-down saturation under Hortonian conditions. Steady-state exchange flux and time to initiate overland flow are within 0.05% and 24%, respectively, of COP results when l.sub.e = H.sub.s =1mm. 3D simulation of a hypothetical catchment demonstrates that the general FOEC sensitivities obtained through 1D simulation are transferrable to the 3D case. This study shows that a value of l.sub.e = H.sub.s provides an appropriate initial value for modelling applications. We suggest a FOEC parameter sensitivity assessment on a case-by-case basis to ensure adequately converged results and to avoid unrealistic model behaviour. Author Affiliation: National Centre for Groundwater Research & Training, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia Article History: Received 20 May 2011; Revised 10 November 2011; Accepted 11 November 2011 Article Note: (miscellaneous) This manuscript was handled by Geoff Syme, Editor-in-Chief
    Keywords: Groundwater -- Analysis ; Depression (Mood disorder) -- Analysis ; Permeability -- Analysis
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Journal of Hydrology, March 6, 2012, Vol.424-425, p.16(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2011.11.051 Byline: Dylan J. Irvine (a)(b), Philip Brunner (c), Harrie-Jan Hendricks Franssen (d), Craig T. Simmons (a)(b) Keywords: Groundwater/surface water interaction; Streambed heterogeneity; Losing streams; Disconnection; Numerical modeling; Inverse modeling Abstract: a* Errors of representing heterogeneous streambeds as homogeneous are assessed. a* For the conditions tested, errors in flux up to [+ or -]34% were observed. a* Maximum errors occurred when stream-aquifer connection state changed. a* For disconnected regimes, maximum errors can be quantified with no streambed data. a* Correctly identifying the state of connection is critical. Author Affiliation: (a) National Centre for Groundwater Research and Training, GPO Box 2100, Adelaide, SA 5001, Australia (b) School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia (c) Centre for Hydrogeology and Geothermics, Rue Emile-Argand 11, CP 158, Neuchatel, Switzerland (d) Agrosphere, IBG-3, Forschungszentrum Julich GmbH, Leo Brandtstrasse, 52425 Julich, Germany Article History: Received 16 March 2011; Revised 25 November 2011; Accepted 28 November 2011 Article Note: (miscellaneous) This manuscript was handled by Geoff Syme, Editor-in-Chief
    Keywords: Hydrogeology -- Analysis ; Hydrogeology -- Models ; Aquifers -- Analysis ; Aquifers -- Models ; Groundwater -- Analysis ; Groundwater -- Models
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Journal of Hydrology, August 5, 2011, Vol.405(3-4), p.333(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2011.05.030 Byline: Ian Cartwright (a)(b), Harald Hofmann (a)(b), Melissa A. Sirianos (a), Tamie R. Weaver (c), Craig T. Simmons (b)(d) Keywords: Murray River; Groundwater; Baseflow; Geochemistry;.sup.222Rn; Drought Abstract: a* Long-term losing stretches of the River Murray become variable gaining during drought conditions. a* Radon, major ion concentrations, and geophysical techniques indentify gaining and losing reaches. a* Groundwater inflows are [approximately equal to]1% of total discharge. a* Low salinity groundwater lenses underlying the river degrade at low river flows. Author Affiliation: (a) School of Geosciences, Monash University, Clayton, Vic. 3800, Australia (b) National Centre for Groundwater Research and Training, GPO Box 2100, Flinders University, Adelaide, SA 5001, Australia (c) URS Australia Pty. Ltd., Level 6, 1 Southbank Blvd., Melbourne, Vic. 3006, Australia (d) School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia Article History: Received 1 September 2010; Revised 1 April 2011; Accepted 18 May 2011 Article Note: (miscellaneous) This manuscript was handled by L. Charlet, Editor-in-Chief, with the assistance of Philippe Negrel, Associate Editor
    Keywords: Nurses -- Chemical Properties ; Groundwater -- Chemical Properties ; Droughts -- Chemical Properties ; Salinity -- Chemical Properties
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Journal of Hydrology, March 6, 2012, Vol.424-425, p.16(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2011.11.051 Byline: Dylan J. Irvine (a)(b), Philip Brunner (c), Harrie-Jan Hendricks Franssen (d), Craig T. Simmons (a)(b) Keywords: Groundwater/surface water interaction; Streambed heterogeneity; Losing streams; Disconnection; Numerical modeling; Inverse modeling Abstract: a* Errors of representing heterogeneous streambeds as homogeneous are assessed. a* For the conditions tested, errors in flux up to [+ or -]34% were observed. a* Maximum errors occurred when stream-aquifer connection state changed. a* For disconnected regimes, maximum errors can be quantified with no streambed data. a* Correctly identifying the state of connection is critical. Author Affiliation: (a) National Centre for Groundwater Research and Training, GPO Box 2100, Adelaide, SA 5001, Australia (b) School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia (c) Centre for Hydrogeology and Geothermics, Rue Emile-Argand 11, CP 158, Neuchatel, Switzerland (d) Agrosphere, IBG-3, Forschungszentrum Julich GmbH, Leo Brandtstrasse, 52425 Julich, Germany Article History: Received 16 March 2011; Revised 25 November 2011; Accepted 28 November 2011 Article Note: (miscellaneous) This manuscript was handled by Geoff Syme, Editor-in-Chief
    Keywords: Hydrogeology -- Analysis ; Hydrogeology -- Models ; Aquifers -- Analysis ; Aquifers -- Models ; Groundwater -- Analysis ; Groundwater -- Models
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Journal of Hydrology, Jan, 2015, Vol.520, p.101(22)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2014.11.020 Byline: Mohammad Mahdi Rajabi, Behzad Ataie-Ashtiani, Craig T. Simmons Abstract: * Polynomial chaos expansions (PCEs) are applied to seawater intrusion modeling. * PCEs can be accurate and fast surrogate models in Monte Carlo simulations. * PCEs can be reliably used in the estimation of moment-independent sensitivity indices. Article History: Received 21 August 2014; Revised 3 November 2014; Accepted 7 November 2014 Article Note: (miscellaneous) This manuscript was handled by Geoff Syme, Editor-in-Chief
    Keywords: Seawater -- Analysis ; Seawater -- Models ; Monte Carlo Methods -- Analysis ; Monte Carlo Methods -- Models
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Journal of Hydrology, December 2018, Vol.567, pp.457-477
    Description: We define model-data interaction (MDI) as a two way process between models and data, in which on one hand data can serve the modeling purpose by supporting model discrimination, parameter refinement, uncertainty analysis, etc., and on the other hand models provide a tool for data fusion, interpretation, interpolation, etc. MDI has many applications in the realm of groundwater and has been the topic of extensive research in the groundwater community for the past several decades. This has led to the development of a multitude of increasingly sophisticated methods. The progress of data acquisition technologies and the evolution of models are continuously changing the landscape of groundwater MDI, creating new challenges and opportunities that must be properly understood and addressed. This paper aims to review, analyze and classify research on MDI in groundwater applications, and discusses several related aspects including: (1) basic theoretical concepts and classification of methods, (2) sources of uncertainty and how they are commonly addressed, (3) specific characteristics of groundwater models and data that affect the choice of methods, (4) how models and data can interact to provide added value in groundwater applications, (5) software and codes for MDI, and (6) key issues that will likely form future research directions. The review shows that there are many tools and techniques for groundwater MDI, and this diversity is needed to support different MDI objectives, assumptions, model and data types and computational constraints. The study identifies eight categories of applications for MDI in the groundwater literature, and highlights the growing gap between MDI practices in the research community and those in consulting, industry and government.
    Keywords: Model-Data Interaction ; Groundwater Modeling ; Uncertainty Analysis ; Data Assimilation ; Data Fusion ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 9
    Language: English
    In: Journal of Hydrology, 12 November 2012, Vol.470-471, pp.280-288
    Description: ► Previous studies frequently neglect seawater volumes in coastal aquifer analyses. ► Analytic methods were developed to explore volume-head-flux relationships. ► Temporal water level trends often fail to represent freshwater storage trends. ► Seawater volume changes are often significant in coastal aquifer water balances. ► Sustainable coastal aquifer management requires seawater volume estimates. The changes in seawater volumes caused by seawater intrusion are often neglected in coastal aquifer management studies. The conditions under which this can result in significant water balance errors are not well understood. Interface movements also influence temporal trends in coastal aquifer water levels, but there is little guidance on this effect. In this study, we use steady-state, sharp-interface, analytic modelling to generate idealised relationships between seawater volume, freshwater volume and water levels. The approach assumes quasi-equilibrium conditions, which are evaluated using a selection of transient, dispersive simulations. The results demonstrate that seawater volume changes can influence significantly coastal aquifer water level trends, relative to the corresponding non-coastal aquifer situation, particularly within deep aquifers with high hydraulic conductivity and low net recharge. It is also shown that seawater volume changes can be a significant component of coastal aquifer water balances, e.g., relative to freshwater discharge to the sea, especially within deep aquifers characterised by low hydraulic conductivity and low freshwater discharge. Transient simulations show that steady-state conditions are a reasonable approximation for a range of transient seawater intrusion situations, including two of the three cases considered in this analysis. We conclude that changes in seawater volumes should be included routinely in coastal aquifer water balances. Also, temporal trends in coastal aquifer water levels may not provide an adequate measure of freshwater storage trends. It follows that the assessment of coastal aquifer condition should consider groundwater levels relative to the hydraulic head imposed by the ocean, accounting for density effects.
    Keywords: Seawater Intrusion ; Coastal Aquifer ; Seawater Volume ; Freshwater Storage ; Sharp Interface ; Vulnerability ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 10
    Language: English
    In: Journal of hydrology, 2012, Vol.414, pp.503-515
    Description: Presently, there is little guidance for model users on the selection of the first-order exchange coefficient (FOEC; or “conductance”) commonly used in simulating surface–subsurface interactions (e.g. infiltration). In this study, relationships between the FOEC and surface–subsurface exchange flux, surface-subsurface head difference and time to initiate overland flow are systematically explored using 1D soil column simulations with the fully integrated code HydroGeoSphere. Numerical experiments adopt five different hydrological scenarios and nine different soil profiles. Results converge on the more accurate, but sometimes more computationally intensive, continuity of pressure (COP) coupling approach as the coupling length (lₑ) parameter within the FOEC is decreased (i.e. FOEC increased). Threshold lₑ values that produce results converged on the COP approach vary considerably with hydrological scenario, soil type and total obstruction height (Hₛ; accounting for sub-grid depression storage), with most threshold lₑ values ⩽10⁻²m. Lower lₑ values are required for infiltration under Hortonian conditions, under non-Hortonian conditions in lower permeability soils, and to capture timing of initiation of overland flow. The condition lₑ〉Hₛ precludes top-down saturation under Hortonian conditions. Steady-state exchange flux and time to initiate overland flow are within 0.05% and 24%, respectively, of COP results when lₑ=Hₛ=1mm. 3D simulation of a hypothetical catchment demonstrates that the general FOEC sensitivities obtained through 1D simulation are transferrable to the 3D case. This study shows that a value of lₑ=Hₛ provides an appropriate initial value for modelling applications. We suggest a FOEC parameter sensitivity assessment on a case-by-case basis to ensure adequately converged results and to avoid unrealistic model behaviour. ; p. 503-515.
    Keywords: Models ; Soil Types ; Soil Profiles ; Overland Flow ; Watersheds ; Permeability
    ISSN: 0022-1694
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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