Ecohydrology of a Floodplain Forest: Relationships Between Evapotranspiration, Vegetation, and Topography at Congaree National Park, South Carolina

Figure 2: Calculating specific yield from storm-induced groundwater change (Harder et al., 2007). BA [sq m]=[0.005454 x (DBH) ]*0.092903 Table 1: Prominent tree species by basal area (m2) for each piezometer site with wetness score (range1-5). Scores closer to 1 indicated more upland species, while scores closer to 5 indicated more facultative or obligate wetland species. Site S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 Topographic features hummock hollow hollow hollow hollow hollow hummock hummock Soil type sand/clay sand/ clay sand/ clay/ silt sand/ clay/ silt sand sand/ clay clay/ sand clay/ sand Specific yield 0.14 ± 0.05 0.19 ± 0.13 0.16 ± 0.10 0.16 ± 0.10 0.19 ± 0.09 0.15 ± 0.10 0.14 ± 0.06 0.19 ± 0.08 ET (mm/day) 10.09 7.5 ± 8 0.85 2.03 5.7 ± 4 4.42 ± 3 10.0 ± 7 1.0 ± 0.3 Basal Area (sq m) 3.83 1.64 2.55 1.76 3.76 4.67 2.60 1.97 Locatio n Wetness Score Prominent Species by Basal Area Common name Latin name photo S-1 3.78 Tupelo Nyssa sp. S-2 2.85 American beech Fagus grandifolia S-3 3.22 Sweetgum Liquidambar styraciflua S-4 4.05 Bald cypress Taxodium distichum S-5 3.40 Loblolly pine Pinus taeda S-6 4.64 Tupelo, bald cypress Nyssa sp. , Taxodium distichum S-7 3.17 Sweetgum Liquidambar styraciflua S-8 3.94 Swamp laurel oak Quercus laurifolia References: Harder, S.V. , Amatya, D.M. , Callahan, T.J., Trettin, C.C. , Hakkila, J. (2007) Hydrology and water budget for a forested Atlantic coastal plain watershed, South Carolina. Journal of the American Water Resources Association 43(3): 563-575. Johnson, A.I. 1967. Specific yield — compilation of specific yields for various materials. U.S. Geological Survey Water Supply Paper 1662-D. U.S. G.P.O. : 1-74. Omernik, J.M. (1987) Ecoregions of the conterminous United States. Map (scale 1:7,500,000). Annals of the Association of American Geographers 77(1): 118-125. Peet, R.K. , Wentworth, T.R. and White, P.S. 1998. A Flexible, Multipurpose Method for Recording Vegetation Composition and Structure. Southern Appalachian Botanical Society. Castanea, Vol. 63, No. 3: 262-274. USDA. 2014. Wetland Indicator Status. United States Department of Agriculture. Walsh, Rush. 2010. Basal Area Guide. Mississippi Wildlife, Fisheries, and Parks: 1-2. White, W. (1932) A method of estimating groundwater supplies based on discharge by plants and evaporation from soil. US Geol. Surv. Water-Supply Paper 659-A. • ET signals were apparent year-round but more pronounced in the summer months (Figure 3). • Specific yield of the sediments were similar and in the expected ranges for fluvial sediments (Table 2). • ET was variable across sites and did not compare to BA, possibly due to microtopographic differences (Table 2). • Vegetation was reflective of bottomland hardwood forest type, however the wetness score differed by site (Table 1). Table 2: Topographic features and summary of soil type, ET, specific yield, and basal area for each piezometer site. Topographic features are defined as either a hummock or hollow. Soil type described during installation of piezometers. time W at er L ev el 14:00 2:00 8:00 20:00 2:00 h s ht1 ht2 Figure 3: Two-week snapshots of water levels in the shallow aquifer for each piezometer. (A) shows diurnal fluctuations in summer. (B) shows these patterns muted in winter. Both graphs have the same color codes. Indicator Status Wetness score Definition Obligate wetland (OBL) 5 almost always occur in wetlands Facultative wetland (FACW) 4 usually occur in wetlands, may occur in non-wetlands Facultative (FAC) 3 occur in both wetlands and non-wetlands Facultative upland (FACU) 2 usually occur in non-wetlands, may occur in wetlands Upland (UPL) 1 almost never occur in wetlands Table 3: Definitions of wetland indicator status and wetness score (USDA, 2014). A B