ABSTRACT: Variable-density flow and transport models require extensive computational resources often resulting in lengthy runtimes, particularly for simulations that represent saltwater intrusion and tidal fluctuations. The majority of saltwater intrusion models do not explicitly represent tidal variations; instead, an average tidal level is assigned to the ocean boundary. By neglecting tidal fluctuations, errors may be introduced if a contaminant included in the simulation reaches the seawater/freshwater interface, and then discharges into the ocean. This paper presents multiple variable-density flow and transport simulations of a coastal aquifer. Each model is conceptually similar; however, tides are either neglected or explicitly included in the ocean boundary. An analysis was performed to determine if the effects of tides could be approximated in simulations with a constant ocean boundary by using apparent dispersivities. The apparent dispersivity value was calculated for each model cell using the velocity variations from the tidal simulation. The transport and discharge patterns of a contaminant plume were used to examine the accuracy of this approach. Use of apparent dispersivity in models with a constant ocean boundary seems to provide a reasonable approach for approximating tidal effects in simulations where explicit representation of tidal fluctuations is not feasible.

Tidal effects on transient dispersion of simulated contaminant concentrations in coastal aquifers

LA LICATA, IVANA;ALBERTI, LUCA
2008-01-01

Abstract

ABSTRACT: Variable-density flow and transport models require extensive computational resources often resulting in lengthy runtimes, particularly for simulations that represent saltwater intrusion and tidal fluctuations. The majority of saltwater intrusion models do not explicitly represent tidal variations; instead, an average tidal level is assigned to the ocean boundary. By neglecting tidal fluctuations, errors may be introduced if a contaminant included in the simulation reaches the seawater/freshwater interface, and then discharges into the ocean. This paper presents multiple variable-density flow and transport simulations of a coastal aquifer. Each model is conceptually similar; however, tides are either neglected or explicitly included in the ocean boundary. An analysis was performed to determine if the effects of tides could be approximated in simulations with a constant ocean boundary by using apparent dispersivities. The apparent dispersivity value was calculated for each model cell using the velocity variations from the tidal simulation. The transport and discharge patterns of a contaminant plume were used to examine the accuracy of this approach. Use of apparent dispersivity in models with a constant ocean boundary seems to provide a reasonable approach for approximating tidal effects in simulations where explicit representation of tidal fluctuations is not feasible.
2008
tidal variation; contaminant transport; density
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/550834
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