Monday, November 13, 2006 - 1:15 PM

Subaqueous Soil-Landscape Models of Chincoteague Bay, Maryland.

Danielle Balduff and Martin Rabenhorst. Univ of Maryland, 1112 HJ Patterson Hall, College Park, MD 20742-5151

Chincoteague Bay is the largest (19,000 ha) of Maryland’s coastal lagoons bounded by Assateague Island to the east and by Maryland’s mainland to the west. Bathymetric data collected in 2003 was used to generate a digital elevation model (DEM) of Chincoteague Bay. Due to the visual obstruction by water, the DEM was used, in conjunction with false color infrared photography, to identify the subaqueous landforms. Subaqueous landscape units were demarcated using water depth, slope, landscape shape, depositional environment (i.e. low-energy or high-energy), and geographical setting (i.e. proximity to barrier island, mainland coast, tidal creeks). Eight subaqueous landforms were identified in Chincoteague Bay: barrier coves, lagoon bottom, mainland coves, paleo-flood tidal delta, shoals, storm-surge washover fan flats, storm-surge washover fan slope, and submerged headlands. One-hundred and fifty soil profiles were described and classified based on Soil Taxonomy. Previously established subaqueous soil-landscape models were evaluated for their applicability in Chincoteague Bay by comparing the characteristics of the observed soils that were located on the various subaqueous landforms. Specific soils identified in Chincoteague Bay sometimes occur on several landscape units, but in general the soils change systematically across the bay from the barrier island to the mainland. Sandy Haplic Sulfaquents (proposed Sulfic Psammowassents) of the Demas series are located on the storm-surge washover fan flats. Sandy Haplic Sulfaquents (proposed Haplic Sulfiwassents) of the Tizzard series are located on the storm-surge washover fan slopes. Coarse-loamy Haplic Sulfaquents (proposed Haplic Sulfiwassents) and fine-silty or clayey Typic Sulfaquents (proposed Typic Sulfiwassents) are located on the lagoon bottom. Fine-silty Typic Sulfaquents (proposed Typic Sulfiwassents) and fine-silty Thapto-Histic Sulfaquents (proposed Thapto-Histic Sulfiwassents) of the Southpoint series are located on submerged headlands and mainland coves. The association of soils with particular landforms further supports the applicability of the soil-landscape paradigm in subaqueous environments.