A Comparative Study of SGD at Three Latitudes in the United States

We present field studies conducted at three locations in the United States with very different climate and coastal conditions.  The first site was in Prince William Sound, Alaska where the beach sediments are coarse (gravel) and the tidal range is around 5.0 m.  The second site was on Tinicum Island in the Delaware Estuary where the sandy sediments are underlain by mud (as the island was the results of final disposal of dredged material).  The tidal range at this site is around 1.3 m.  The third site is in Grand Isle State Park Louisiana in the Gulf of Mexico.   The tidal range at this site is around 1.2 m.  The submarine groundwater discharge was computed at the three sites using the finite element model MARUN (Boufadel et al., 1999, J. of Contaminant Hydrology).  Preliminary results indicate that the SGD is greatly dependent on the parameterization of the beach lower boundary.  We present a dimensionless formulation that allows direct comparison of the results.