Saltwater Intrusion Hydrodynamics in a Tidal Aquifer
Publication: Journal of Hydrologic Engineering
Volume 13, Issue 9
Abstract
The saltwater freshwater interface at the intertidal zones of surficial aquifers is continuously influenced by tidal effects. The numerical solution of this continuously changing intertidal saltwater interface profile is difficult. To simulate this dynamic system correctly appropriate definition and use of seaside boundary conditions are necessary. The estimation of submarine groundwater discharge may vary significantly depending on the way these boundary conditions are handled on the intertidal zone. In this study we have investigated this problem numerically to evaluate the effect of the use of different intertidal zone boundary conditions on the magnitude and the direction of submarine groundwater discharge as well as their effect on saltwater interface profiles. Our findings indicate that the numerical results are sensitive to density differences between the freshwater and seawater phases along with the type of boundary condition used at the intertidal zone. Based on these results, we conclude that the adaptable free exit boundary condition introduced by Frind in 1988 is the proper boundary condition to use on the advection dominant intertidal zone boundary. This approach necessitates the use of nontraditional boundary conditions in the transport model to prevent the artificial accumulation of saltwater mass underneath this boundary. The use of an improper boundary condition at this boundary may lead to the development of artificial fingering due to the accumulation of saltwater mass in the intertidal zone.
Get full access to this article
View all available purchase options and get full access to this article.
References
Ataie-Ashtiani, B., Volker, R. E., and Lockington, D. A. (1999). “Tidal effects on sea water intrusion in unconfined aquifers.” J. Hydrol., 216, 17–31.
Bear, J. (1979). Hydraulics of groundwater, Vol. 18, McGraw-Hill International, New York.
Boufadel, M. C. (2000). “A mechanistic study of nonlinear solute transport in a groundwater-surface water system under steady state and transient hydraulic conditions.” Water Resour. Res., 36, 2549–2565.
Burnett, W. C., et al. (2006). “Submarine groundwater discharge: Its measurement and influence on the coastal zone.” J. Coastal Res., 1, 35–38.
Cartwright, N., et al. (2006). “Application of a coupled ground-surface water flow model to simulate periodic groundwater flow influenced by a sloping boundary, capillarity and vertical flows.” Environ. Modell. Software, 21(6), 770–778.
Croucher, A. E., and Osullivan, M. J. (1995). “The Henry problem for saltwater intrusion.” Water Resour. Res., 31, 1809–1814.
Diersch, H. J. G., and Kolditz, O. (1998). “Coupled groundwater flow and transport. 2: Thermohaline and 3D convection systems.” Adv. Water Resour., 21, 401–425.
Elder, J. W. (1967). “Transient convection in a porous medium.” J. Fluid Mech., 27, 609–623.
Frind, E. O. (1982). “Simulation of long-term transient density-dependent transport in groundwater.” Adv. Water Resour., 5, 73–78.
Frind, E. O. (1988). “Solution of the advection-dispersion equation with free exit boundary.” Numer. Methods Partial Differ. Equ., 4, 301–313.
Gallardo, A. H., and Marui, A.(2006). “Submarine groundwater discharge: An outlook of recent advances and current knowledge.” Geo-Mar. Lett., 26(2), 102–113.
Gunduz, O., and Aral, M. M. (2005). “A Dirac-delta function notation for source/sink terms in groundwater flow.” J. Hydrol. Eng., 10(5), 420–427.
Henry, H. R. (1964). “Effects of dispersion on salt encroachment in coastal aquifers.” U.S. Geological Survey Water Supply Paper, 1613-C, C71-C84.
Huyakorn, P. S., Andersen, P. F., Mercer, J. W., and White, H. O. (1987). “Saltwater intrusion in aquifers—Development and testing of a 3-dimensional finite-element model.” Water Resour. Res., 23, 293–312.
Jang, W. Y., and Aral, M. M. (2007). “Density-driven transport of volatile organic compounds and its impact on contaminated groundwater plume evolution.” Transp. Porous Media, 67, 53–374.
Kolditz, O., Ratke, R., Diersch, H. J. G., and Zielke, W. (1998). “Coupled groundwater flow and transport. 1. Verification of variable density flow and transport models.” Adv. Water Resour., 21, 27–46.
Mango, A. J., et al. (2004). “Tidally induced groundwater circulation in an unconfined coastal aquifer modeled with a Hele–Shaw cell.” Geology, 32(3), 233–236.
Mao, X., Enot, P., Barry, D. A., Li, L., Binley, A., and Jeng, D.-S. (2006). “Tidal influence on behaviour of a coastal aquifer adjacent to a low-relief estuary.” J. Hydrol., 327, 110—127.
Oldenburg, C. M., and Pruess, K. (1995). “Dispersive transport dynamics in a strongly coupled groundwater-brine flow system.” Water Resour. Res., 31, 289–302.
Park, C.-H. (2004). “Saltwater intrusion in coastal aquifers.” Ph.D. thesis, Georgia Institute of Technology, Atlanta.
Park, C.-H., and Aral, M. M. (2007). “Sensitivity of the solution of the Elder problem to density, velocity, and numerical perturbations.” J. Contam. Hydrol., 92, 33–49.
Pinder, G. F., and Gray, W. G. (1977). Finite-element simulation in surface and subsurface hydrology, Vol. 12, Academic, New York.
Rathfelder, K., and Abriola, L. M. (1994). “Mass conservative numerical-solutions of the head-based Richards equation.” Water Resour. Res., 30, 2579–2586.
Slomp, C. P., and Van Cappellen, P. (2004). “Nutrient inputs to the coastal ocean through submarine groundwater discharge: Controls and potential impact.” J. Hydrol., 295, 64–86.
Smith, A. J. (2004). “Mixed convection and density-dependent seawater circulation in coastal aquifers.” Water Resour. Res., 40, W08309 .
Swarzenski, P. W., et al. (2006). “Biogeochemical transport in the Loxahatchee River estuary, Florida: The role of submarine groundwater discharge.” Mar. Chem., 101(3–4), 248–265.
Uchiyama, Y., et al. (2000). “Submarine groundwater discharge into the sea and associated nutrient transport in a sandy beach.” Water Resour. Res., 36(6), 1467–1479.
van Genuchten, M. T. (1980). “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.” Soil Sci. Soc. Am. J., 44, 892–898.
Voss, C. I., and Souza, W. R. (1987). “Variable density flow and solute transport simulation of regional aquifers containing a narrow fresh-water-saltwater transition zone.” Water Resour. Res., 23, 1851–1866.
Yeh, G. T. (1981). “On the computation of Darcian velocity and mass balance in the finite-element modeling of groundwater-flow.” Water Resour. Res., 17, 1529–1534.
Zhang, Q., Volker, R. E., and Lockington, D. A. (2001). “Influence of seaward boundary condition on contaminant transport in unconfined coastal aquifers.” J. Contam. Hydrol., 49, 201–215.
Information & Authors
Information
Published In
Journal of Hydrologic Engineering
Volume 13 • Issue 9 • September 2008
Pages: 863 - 872
Copyright
© 2008 ASCE.
History
Received: Jul 23, 2007
Accepted: Dec 6, 2007
Published online: Sep 1, 2008
Published in print: Sep 2008
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.