HR: 0800h
AN: H41C-0305    [Abstracts]
TI: Sediment Transport and Deposition in Tidal Riparian Wetlands During Drought Conditions
AU: * Renfro, A A
EM: arenfro@ic.sunysb.edu
AF: SUNY Stony Brook, Marine Science Research Center, Stony Brook, NY 11794 United States
AU: Leonard, L A
EM: lynnl@uncw.edu
AF: University of North Carolina, 1 Marvin Moss Lane, Stony Brook, NY 28409 United States
AU: Croft, A L
EM: crofta@uncw.edu
AF: University of North Carolina, 1 Marvin Moss Lane, Stony Brook, NY 28409 United States
AB: Rates of sediment deposition in coastal riparian wetland are determined, in part, by the amount of sediment available in the flooding waters. In the Lower Cape Fear River (LCFR) estuary in southeastern North Carolina total suspended solids (TSS) are received from three major tributaries: Cape Fear mainstem (CFR), Northeast Cape Fear (NECFR), and Black Rivers (BR). The sediment delivered to the estuary depends on the tributary characteristics and climatological conditions in the watersheds. In coastal North Carolina, two primary types of streams, brown-water and black-water, drain vastly different headwater areas and therefore contrast greatly in the amount of sediment they carry and can potentially deposit in adjacent swamps. TSS concentrations in the brown-water river (Cape Fear River) range from 5-35 mg L$^{-1}$, but TSS are typically lower (<10 mg L$^{-1}) in the black-water streams. From spring 2000 to winter 2002 severe drought conditions were present, particularly in the piedmont region. Although streamflow was reduced during drought conditions, mean TSS concentrations were significantly higher during the drought than during normal conditions for both the CFR and NECFR. At a swamp adjacent to CFR total and inorganic suspended sediment concentrations decreased slightly, but not significantly over time during drought conditions, suggesting a loss of suspended sediment to the wetland surface. During normal conditions TSS and ISS concentrations increased slightly, but not significantly, suggesting inhibited settling or export. Sediment deposition data during the drought was consistent with the flux data indicating deposition did not differ significantly between normal and drought conditions. However, total and inorganic deposition was higher during the drought period. At a swamp adjacent to the NECFR suspended sediment concentrations did not vary relative to high tide for either normal or drought conditions. Sediment trap data indicated little difference in deposition between drought and normal conditions. These results indicate short-term changes in climatological conditions may affect deposition rates in tidal riparian swamps. Additional data are needed to examine the extent of drought effects on deposition.
DE: 1812 Drought
DE: 1815 Erosion and sedimentation
DE: 1890 Wetlands
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting