Sedimentation Cycles in a River-Mouth Tidal Freshwater Marsh

Tidal freshwater marshes are critical buffers that exist at the interface between watersheds and estuaries. Little is known about the physical dynamics of tidal freshwater marsh evolution. Over a 21 month period from July 1995 to March 1997, measurements were made of biweekly sediment deposition at 23 locations in a 3.8 hectare tidal freshwater marsh in the Bush River subestuary of the upper Chesapeake Bay. Bi-weekly accumulation showed high spatial and temporal variability, ranging from -0.28 to 1.15 g cm-2. Spatial variability is accounted for by habitat differences including plant associations, elevation, and hydrology. Temporal variability is accounted for by interannual climate variability, the growth cycles of marsh plants, stream-marsh interactions, forest-marsh interactions, and animal activity.