Controls of sediment transport and deposition in an incised mainland marsh basin, southeastern North Carolina

Sedimentation on the surface of tidal marshes is a process that is controlled by the interactions of a complex set of variables. To adequately describe the patterns of sediment transport and deposition in any particular system requires extensive sampling of biological, physical, sedimentological, and geomorphological parameters. In this study, measurements of sediment deposition, marsh elevation, water level, total suspended solid (TSS) loads, overmarsh current speeds, and vegetative cover were used to determine which of these factors control sediment distribution patterns in a small marsh basin in southeastern North Carolina. The results of this study suggest that marsh elevation exerted significant control over deposition but that its effects were largely muted by other processes. Creek hydrology, sediment instability associated with areas of new creek development, plant/flow interactions, and tidal creek TSS concentrations also influenced sediment deposition in the study area. Flow patterns, resulting from the interaction between tidal stage and marsh topography, controlled the dispersal of particulate matter across the marsh surface and contributed to significant depositional differences among sampling sites as a function of tidal stage. The results of this study indicate that tidal creek geometry, creek channel position, and tidal stage interact synergistically to control sediment/particulate delivery on the surfaces of tidal wetlands.