USING GIS, LiDAR AND CORE TO INTEGRATE GEOMORPHOLOGY, STRATIGRAPHY AND HYDROGEOLOGIC MANAGEMENT UNITS, IN THE VICINITY OF THE CROATAN NATIONAL FOREST, NEUSE RIVER BASIN, NORTH CAROLINA

A preliminary derivative map of hydrogeologic management units, is presented for a sector of the Croatan National Forest in the Neuse River Basin, North Carolina. Hydrogeologic management units are derived from maps of 1) geomorphic features interpreted from LiDAR elevation data, 2) Quaternary surficial stratigraphic units identified in cores and outcrops, and 3) hydrologically attributed landscape units based on soils coverages. Hydrologic attributes include recharge, texture and permeability.

The Croatan National Forest and adjacent Hofmann State Forest are located on the south side of the Neuse Estuary, near the boundary between the middle and lower Coastal Plain. This region includes a series of terraces, < 15 m above mean sea level (MSL), and intervening paleoshorelines with Pleistocene highstand elevations of about 9 m and 4.6 m above MSL. North of the Neuse River, the Suffolk Scarp forms the Arapaho Ridge, a prominent paleobarrier island complex that may have formed at a highstand of about 9 m (local shoreface toe at 6 m). On the south side of the Neuse, the projected axis of the Arapaho Ridge into the Croatan Forest is marked by a sandy shoal complex that lacks a steep shoreface.

Dubar and others (1974) provided a generalized map of the geomorphology of the Croatan area, and a cross section along the Neuse River's outcrops in which they defined the Yorktown (Pliocene), James City (early Pleistocene), and Flanner Beach (mid? Pleistocene) Formations, and the late Pleistocene “Cherry Point” unit. By building on this previous work, geomorphic map units are further defined using LiDAR (Light Detection and Ranging), a remote sensing technique that provides high-resolution elevation data. Strike parallel and dip-parallel geologic cross sections were constructed for the region. In cores (<67 m deep, spacing < 3 km), we defined facies, surficial units, subcrops, and potential aquifers and confining units. Surficial stratigraphic units, defined from landforms and facies were correlated with an established stratigraphic model for southeastern Virginia (see Mixon and others, 1989; Johnson and Berquist, 1989). Derivative maps were developed that attach hydrogeologic attributes to geomorphic and geologic map units.