NASA LaRC is located in an area of low topographic relief surrounded by a shallow estuarine environment. The Center is close to the northwest and southwest branches of the Back River, and is within the tidal zone of the Chesapeake Bay. The principal drainage ways in the vicinity of the Center, Brick Kiln Creek and Tabbs Creek are tidal creeks with extensive tidal marshes.
In 1991 Old Dominion University (ODU) performed a wetland field survey at NASA LaRC to identify and map the boundaries of forested wetlands. The predominant wetland areas in the vicinity of NASA LaRC identified were the tidal marsh wetlands associated with Brick Kiln Creek and Tabbs Creek. These wetland areas were identified as an estuarine emergent marsh dominated by nearly uniform stands of saltmarsh cordgrass (Spartina alternaflora) in the lower intertidal zone, and saltmarsh hay (S. patens) and salt grass (Distichlis spicata) in the high intertidal zone. Additional dominants in the high marsh were groundsel tree (Baccharus halmifolia), rush (Juncus spp.), big cordgrass (S. cynosuroides) and marsh elder (Iva fructens). Common reed (Phragmites australis) was common around the upper fringes of the marshes and in areas that have been disturbed by materials such as fill and riprap.
The ODU survey identified three types of forested wetlands at the Center: red maple (Acer rubrum) swamp, sweetgum (Liquidambar styraciflua) swamp, and water oak (Quercus nigra) pond wetlands. The red maple swamp wetland is dominated by red maple with some sweetgum. The sweetgum swamp is dominated by sweetgum, with black gum (Nyssa sylvatica) and willow oak (Q. phellos). The water oak pond wetland is dominated by water oak and laurel oak (Q. laurifolia). These wetlands were identified primarily along the upper reaches of the Brick Kiln Creek and Tabbs Creek marsh wetlands, and in the undeveloped portion of the LaRC West Area. The survey determined that the forested wetlands may be remnants of a larger wetland area that had been converted to non-wetland by ditches and draining. Shrub-scrub wetlands were identified in limited areas, mostly in ditches adjacent to the marsh wetlands. Young red maple, sweetgum, and willow (Salix sp.) characterize the shrub-scrub wetlands.
In 2001, as part of a potential development project and at LaRC’s request, the USACE reviewed the wooded property to the south and east of the Center’s main gate and determined that no jurisdictional wetlands exist at the site.
In the fall of 2004, to update and verify portions of the 1991 ODU survey, NASA LaRC performed a wetlands delineation study on approximately 134 acres of mixed pine, hardwood forest and lawn. Field reconnaissance of the wooded portion of the site found the canopy to be approximately 50 years old, consisting primarily of sweet-gum (Liquidambar styraciflua) and red maple (Acer rubrum). The subcanopy is composed of red maple, sweet-gum, and paw paw (Asimina triloba). The sapling/shrub stratum consists of predominantly paw paw, American holly (Ilex opaca), and waxmayrtle (Myrica cerifera). The herbaceous stratum in the upland areas consists of primarily Japanese honeysuckle (Lonicera japonica) and Virginia Creeper (Parthenocissus quinquefolia). The herbaceous strata in the non-tidal wetlands consists primarily of jack-in-the-pulpit (Arisaema triphyllum), poison ivy (Toxicodendron radicans), and sedges (Carex spp.). The herbaceous strata in the tidal wetlands consist of common reed (Phragmities australis) salt grass (Distichlis spicata) and cord grass (Spartina alterniflora). Soils on the property are mapped by the USDA Soil Conservation Service as part of the Soil Survey of Tidewater Cities Area, Virginia. Soils are mapped throughout the study area as Chickahominy silt loam and Bohicket muck. Field findings indicated the soils primarily consisted of poorly drained to moderately well-drained, dark gray (10YR 4/1) and grayish brown (10YR 5/2) soils, with mottling in many areas. Hydrologic indicators of non-tidal wetlands on-site consist of primary and secondary indicators. Primary indicators observed were inundation, saturation within 12 inches, watermarks, sediment deposits and drainage patterns. Secondary indicators included a positive facultative (FAC)-neutral test, hypertrophied lenticels, shallow rooting, fluting and multiple trunks.
Wetlands delineation survey reports and USACE jurisdictional determination letters are maintained by the LaRC Environmental Management Office. Current map data is maintained by the LaRC GIS team and is incorporated into the Center’s master plan website.
