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

Abstract

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, physicM, 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 detern~ne 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, plmnt/flow interactions, and tidal creek TSS concentrations also influenced sediment deposition in the study area. Flow patterns, resuking 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.

Control of sediment deposition rates in two mid-Atlantic Coast tidal freshwater wetlands

“…Elevation is largely a surrogate for flood depth and duration because higher points on the marsh are generally inundated less frequently and for shorter duration than lower points. The sediment deposition vs. elevation relationship in Mattaponi tidal freshwater wetlands is similar to that found by Pasternack et al (2000) in a tidal freshwater marsh (r ¼ ÿ0:66, p < 0:0001), and Leonard (1997) in a salt marsh (r ¼ ÿ0:53, p < 0:0001).…”

“…During the year-long study, rates ranged from 0.8 AE 0.2 to 73.2 AE 22.5 g m ÿ2 d ÿ1 (Fig. 3a), and were comparable to rates in a North Carolina salt marsh (13.8 AE 3.4 to 63.7 AE 10.3 g m ÿ2 d ÿ1 ; Leonard, 1997). During the winter and early spring, sediment deposition rates at Gleason Marsh and Walkerton Marsh were low and similar (Fig.…”

“…The ISCO sampler was located on a dock that extended over the mudflat to the river channel at each site. Water samples (250 ml) were collected hourly for 24 h. In the laboratory, the surficial floodwater and river water samples were filtered through 1 lm pre-combusted, pre-weighed Gelman glass fiber filters, rinsed three times with de-ionized water, oven-dried to a constant weight at 60 C, and weighed to 0.1 mg (Franson, 1989;Leonard, 1997).…”

“…Factors that have been implicated in controlling sediment deposition rates include elevation (Christiansen, 1998;Hensel, Pont, and Day, 1999), flood depth and duration (Asselman & Middelkoop, 1998;Cahoon et al, 1995;Christiansen, Wiberg, & Milligan, 2000), surficial floodwater velocity (Christiansen, 1998;Christie, Dyer, & Turner, 1999;Yang, 1998), river suspended sediment load (Asselman & Middelkoop, 1998;Blanton, Clark, Alber, & Kineke, 1999;Callaway et al, 1996;Christiansen, 1998;Christie et al, 1999;French, Spencer, Murray, Arnold, 1993), surficial floodwater suspended sediment load (Christiansen et al, 2000), proximity to sediment source (Brown et al, 1998;Callaway et al, 1996), and the presence of vegetation (Brown et al, 1998;Cahoon & Turner, 1989;Callaway et al, 1996;Christiansen, 1998;Christiansen et al, 2000;Hutchinson, Sklar, & Roberts, 1995;Yang, 1998). These studies suggest that there is a high degree of variability associated with sediment deposition, and that several factors may act synergistically to control rates in any given salt marsh (Leonard, 1997).…”

Can Mangroves Help Combat Sea Level Rise Through Sediment Accretion and Accumulation?

“…Generally, the rate of sediment deposition depends on the tidal frequency and its duration that flooded the mangrove ecosystem [42,43]. In the present study, monthly tidal frequency and inundation duration that flooded the study area were not remarkably varied throughout the year.…”