Elevated suspended sediment concentrations in fluvial systems are deleterious to fluvial ecosystems. In these systems, increases in total suspended solids (TSS) following rain events have been well documented. The impacts of rainfall on marsh surface sediments have received less attention. This study examined the relationship between rainfall and TSS in a tidal creek adjacent to upland and marsh surfaces.
TSS concentrations were measured for two locations in Bradley Creek in southeastern North Carolina; one tidal site and one non-tidal, headwater site. TSS concentrations at the tidal site were significantly higher during the growing season than during the non-growing season. The headwater site showed no significant change in TSS seasonally. No significant difference in TSS concentrations was found between spring and neap tides. During fair weather at the tidal site, flood tide TSS concentrations were greater than ebb tide TSS concentrations, which were greater than low tide TSS concentrations. Mean fair weather TSS concentrations at the headwater site were 1.0 mg L-1. TSS concentrations increased to 11.9 mg L-1 following rain events. At the tidal site, mean fair weather TSS concentrations were 10.9 mg L-1 at ebb tide, 7.9 mg L-1 at low tide, and 13.5 mg L-1 at flood tide. At the tidal site, mean TSS concentrations following rain events increased to 22.5 mg L-1 at ebb tide, 21.8 mg L-1 at low tide, and 20.9 mg L-1 at flood tide.
These data suggest that following rain events in Bradley Creek, upland runoff has a greater impact on increasing TSS than does runoff from the marsh surface. It is not believed that a significant amount of sediment is removed from the marsh during low tide rain events
