Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision

Gareth Robinson, Ashraf Ahmed, Gerard Hamill

    Research output: Contribution to conferencePaper

    Abstract

    This study investigates the effects of ground heterogeneity, considering permeability as a random variable, on an intruding SW wedge using Monte Carlo simulations. Random permeability fields were generated, using the method of Local Average Subdivision (LAS), based on a lognormal probability density function. The LAS method allows the creation of spatially correlated random fields, generated using coefficients of variation (COV) and horizontal and vertical scales of fluctuation (SOF). The numerical modelling code SUTRA was employed to solve the coupled flow and transport problem. The well-defined 2D dispersive Henry problem was used as the test case for the method. The intruding SW wedge is defined by two key parameters, the toe penetration length (TL) and the width of mixing zone (WMZ). These parameters were compared to the results of a homogeneous case simulated using effective permeability values. The simulation results revealed: (1) an increase in COV resulted in a seaward movement of TL; (2) the WMZ extended with increasing COV; (3) a general increase in horizontal and vertical SOF produced a seaward movement of TL, with the WMZ increasing slightly; (4) as the anisotropic ratio increased the TL intruded further inland and the WMZ reduced in size. The results show that for large values of COV, effective permeability parameters are inadequate at reproducing the effects of heterogeneity on SW intrusion.
    LanguageEnglish
    Number of pages4
    Publication statusPublished - 16 Jun 2014
    EventSWIM23 - 23 Salt Water INtrusion Meeting - Husumhus - 25813 Husum, Germany
    Duration: 16 Jun 201420 Jun 2014

    Conference

    ConferenceSWIM23 - 23 Salt Water INtrusion Meeting
    CountryGermany
    CityHusumhus - 25813 Husum
    Period16/06/201420/06/2014

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    saline intrusion
    penetration
    aquifer
    permeability
    probability density function
    simulation
    analysis
    modeling
    method
    parameter
    effect

    Cite this

    Robinson, G., Ahmed, A., & Hamill, G. (2014). Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision. Paper presented at SWIM23 - 23 Salt Water INtrusion Meeting, Husumhus - 25813 Husum, Germany.
    Robinson, Gareth ; Ahmed, Ashraf ; Hamill, Gerard. / Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision. Paper presented at SWIM23 - 23 Salt Water INtrusion Meeting, Husumhus - 25813 Husum, Germany.4 p.
    @conference{807ba2b52d8e46768eb61177f6d61e8b,
    title = "Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision",
    abstract = "This study investigates the effects of ground heterogeneity, considering permeability as a random variable, on an intruding SW wedge using Monte Carlo simulations. Random permeability fields were generated, using the method of Local Average Subdivision (LAS), based on a lognormal probability density function. The LAS method allows the creation of spatially correlated random fields, generated using coefficients of variation (COV) and horizontal and vertical scales of fluctuation (SOF). The numerical modelling code SUTRA was employed to solve the coupled flow and transport problem. The well-defined 2D dispersive Henry problem was used as the test case for the method. The intruding SW wedge is defined by two key parameters, the toe penetration length (TL) and the width of mixing zone (WMZ). These parameters were compared to the results of a homogeneous case simulated using effective permeability values. The simulation results revealed: (1) an increase in COV resulted in a seaward movement of TL; (2) the WMZ extended with increasing COV; (3) a general increase in horizontal and vertical SOF produced a seaward movement of TL, with the WMZ increasing slightly; (4) as the anisotropic ratio increased the TL intruded further inland and the WMZ reduced in size. The results show that for large values of COV, effective permeability parameters are inadequate at reproducing the effects of heterogeneity on SW intrusion.",
    author = "Gareth Robinson and Ashraf Ahmed and Gerard Hamill",
    year = "2014",
    month = "6",
    day = "16",
    language = "English",
    note = "SWIM23 - 23 Salt Water INtrusion Meeting ; Conference date: 16-06-2014 Through 20-06-2014",

    }

    Robinson, G, Ahmed, A & Hamill, G 2014, 'Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision' Paper presented at SWIM23 - 23 Salt Water INtrusion Meeting, Husumhus - 25813 Husum, Germany, 16/06/2014 - 20/06/2014, .

    Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision. / Robinson, Gareth; Ahmed, Ashraf; Hamill, Gerard.

    2014. Paper presented at SWIM23 - 23 Salt Water INtrusion Meeting, Husumhus - 25813 Husum, Germany.

    Research output: Contribution to conferencePaper

    TY - CONF

    T1 - Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision

    AU - Robinson, Gareth

    AU - Ahmed, Ashraf

    AU - Hamill, Gerard

    PY - 2014/6/16

    Y1 - 2014/6/16

    N2 - This study investigates the effects of ground heterogeneity, considering permeability as a random variable, on an intruding SW wedge using Monte Carlo simulations. Random permeability fields were generated, using the method of Local Average Subdivision (LAS), based on a lognormal probability density function. The LAS method allows the creation of spatially correlated random fields, generated using coefficients of variation (COV) and horizontal and vertical scales of fluctuation (SOF). The numerical modelling code SUTRA was employed to solve the coupled flow and transport problem. The well-defined 2D dispersive Henry problem was used as the test case for the method. The intruding SW wedge is defined by two key parameters, the toe penetration length (TL) and the width of mixing zone (WMZ). These parameters were compared to the results of a homogeneous case simulated using effective permeability values. The simulation results revealed: (1) an increase in COV resulted in a seaward movement of TL; (2) the WMZ extended with increasing COV; (3) a general increase in horizontal and vertical SOF produced a seaward movement of TL, with the WMZ increasing slightly; (4) as the anisotropic ratio increased the TL intruded further inland and the WMZ reduced in size. The results show that for large values of COV, effective permeability parameters are inadequate at reproducing the effects of heterogeneity on SW intrusion.

    AB - This study investigates the effects of ground heterogeneity, considering permeability as a random variable, on an intruding SW wedge using Monte Carlo simulations. Random permeability fields were generated, using the method of Local Average Subdivision (LAS), based on a lognormal probability density function. The LAS method allows the creation of spatially correlated random fields, generated using coefficients of variation (COV) and horizontal and vertical scales of fluctuation (SOF). The numerical modelling code SUTRA was employed to solve the coupled flow and transport problem. The well-defined 2D dispersive Henry problem was used as the test case for the method. The intruding SW wedge is defined by two key parameters, the toe penetration length (TL) and the width of mixing zone (WMZ). These parameters were compared to the results of a homogeneous case simulated using effective permeability values. The simulation results revealed: (1) an increase in COV resulted in a seaward movement of TL; (2) the WMZ extended with increasing COV; (3) a general increase in horizontal and vertical SOF produced a seaward movement of TL, with the WMZ increasing slightly; (4) as the anisotropic ratio increased the TL intruded further inland and the WMZ reduced in size. The results show that for large values of COV, effective permeability parameters are inadequate at reproducing the effects of heterogeneity on SW intrusion.

    M3 - Paper

    ER -

    Robinson G, Ahmed A, Hamill G. Stochastic Analysis of Saltwater Intrusion in Heterogeneous Aquifers using Local Average Subdivision. 2014. Paper presented at SWIM23 - 23 Salt Water INtrusion Meeting, Husumhus - 25813 Husum, Germany.