Representing the Coastal Boundary Condition in Regional Groundwater Flow Models
Publication: Journal of Hydrologic Engineering
Volume 14, Issue 8
Abstract
Numerical experiments were performed to investigate how the coastal boundary condition could be approximated in a groundwater flow model to yield accurate values for hydraulic heads and fluxes in the freshwater part of a coastal aquifer. These experiments consisted of obtaining steady-state solutions for hydraulic heads in a vertical cross section using the groundwater flow code MODFLOW and comparing the results to a steady-state solution in a similar cross section for equivalent freshwater heads obtained using the variable-density flow and transport code SEAWAT, which was considered to be the accurate solution to the problem. Six different boundary conditions that have been used to approximate the coastal boundary in groundwater flow models were tested, and simulations were run for both specified-flux and specified-head boundary conditions at the upstream freshwater boundary. For both upstream boundary conditions, the MODFLOW solution that best matched the SEAWAT solution for hydraulic heads and fluxes in the freshwater part of the aquifer was the solution in which equivalent freshwater heads were specified over the full thickness of the aquifer at the coastal boundary.
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Acknowledgments
Financial support for this investigation was provided in part by the St. Johns River Water Management District, Palatka, Fla., the Florida Water Resources Research Center, and the U.S. Geological Survey State Water Research Institute Program. The information in this paper represents the opinions and conclusions of the writers, and it does not necessarily represent the official position of the St. Johns River Water Management District, the Florida Water Resources Research Center, or the U.S. Geological Survey.
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Information & Authors
Information
Published In
Journal of Hydrologic Engineering
Volume 14 • Issue 8 • August 2009
Pages: 821 - 831
Copyright
© 2009 ASCE.
History
Received: Feb 19, 2008
Accepted: Nov 3, 2008
Published online: Feb 19, 2009
Published in print: Aug 2009
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