HYDROLOGY AND WATER QUALITY OF SEEPAGE SLOPE WETLANDS ON THE SC COASTAL PLAIN

Abstract

Seepage wetlands occur on the Southeastern Coastal Plain at the base of slopes, generally at the outer edge of a floodplain or stream corridor. Unlike riverine wetlands, however, these wetlands receive most of their water from seeps and springs that discharge shallow groundwater from adjacent upslope land. These wetlands are typically saturated or wet even during dry seasons, a further expression of the dominance of groundwater seepage. Although not widely studied, they are a prominent feature of the landscape in many of the places they occur. This poster represents a part of a larger project, the purpose of which is to begin a characterization of the site and landscape ecology of these wetlands. We selected two seeps at each of two different sites. One site is in Francis Beidler Forest (Four Holes Swamp, Dorchester County) and the other is in the Wannamaker Nature Preserve (Lyons Creek, Calhoun County). The adjacent upland at the Four Holes Swamp site is medium aged mixed hardwood with planted pine set back 50-100 m. The upland at the Lyons Creek site is a mature mixed hardwood forest. We installed shallow wells with water level recorders at each seep and a recording rain gauge was deployed nearby. The two sites vary by soil type, upland and slope topography, and land use. In addition to continuous water level and precipitation recording we collect water samples from the wells seasonally and analyze them for dissolved organic carbon (DOC) and nitrogen and phosphorus species. Thus far we have completed summer, autumn, and winter samples. The two sites differ in their hydrologic response to precipitation events. Nutrient concentrations also differ both seasonally and between sites. DOC concentrations are less variable. This project will continue for a least another season, with plans for ongoing work at these sites and others.