HYDROGEOLOGIC VARIATIONS ACROSS A BARRIER ISLAND, FALSE CAPE STATE PARK, VIRGINIA

False Cape State Park, located in southeastern Virginia Beach, Virginia contains a complex suite of barrier island features. The appearance and subsequent disappearance of redoximorphic wetland soil features in the young, sandy soils of the interdunal swales here may stem from variations in soil moisture conditions related to vertical and lateral groundwater flow on the island. Initial head data from monitoring wells indicate that a strongly asymmetric water table mound crests under the eastern half of the island. This asymmetry could be due to differences in either the vegetation cover or the permeability of stratigraphic packages. The densely-vegetated western half of the island experiences higher rates of evapotranspiration (ET) than the more barren dunes on the eastern half. Results of groundwater models that spatially vary ET rates, and thus recharge, generate an asymmetric freshwater lens across an island with uniform permeability. However, sedimentation and stratigraphic differences may prove to be more important than ET. Transducer data show that aquifer responses to rapid recharge events vary across the island in ways which suggest that sediment packages on either side of the island may have different net permeabilities. Uniform recharge across an island with varying transmissivities can also produce asymmetric watertable shapes. Stratigraphic analyses of vibracore and ground penetrating radar (GPR) data will help in testing these working hypotheses.