LIKE FINDING A GRAIN OF SAND IN A BUCKET OF MUD: LOCATING SAND RESOURCES IN THE DELAWARE ESTUARY

It has become imperative for coastal managers to better understand the resources and interrelationships of the components within the coastal ecosystems. Through an integrated program by the Delaware Coastal Program (DNREC) and the University of Delaware Geosciences Department a benthic and sub-bottom imaging project to identify and map the benthic habitat and sub-bottom sediments of Delaware Bay and River has been conducted.

Locating potential sand resources, that are laterally and vertically extensive, for beach replenishment and coastal restoration can be very challenging in a muddy heterogeneous environment. Integrating detailed surface and sub-surface mapping in a 3D GIS database has allowed the program to identify” islands” of sand with a fine grained dominated benthic environment, as well as identify unexposed subsurface continuous sand deposits . Integrating our knowledge of the Pleistocene and Holocene paleoenvironmental settings with our understand of the distribution of surface and sub-surface sediments through remote acoustics, the project was able to locate sand borrow sites: that will aid in the future planning for the increased coastal resiliency for the Town of Bowers Beach, and protect and enhance Horseshoe Crab/shorebird habitat at Mispillion Inlet (a location considered to be the most important Horseshoe crab spawning beach within the entire Mid-Atlantic).

The 3D GIS integration allowed for sand replenishment borrow sites to be identified based upon the desired sediment grain sizes, thickness of sediment overburden, and volumetric requirements; and then subsequently delineated to areas that would minimize the effects upon potential essential fish habitat.