The Influence of Tidal Flow and Channel Order on Sedimentation and Hydrodynamics in Two Macrotidal Creeks in the Bay of Fundy

The hydrodynamics and sediment characteristics of two tidal creeks in the Upper Bay of Fundy were measured along a transect from the thalweg to the high marsh surface. The two study areas were Starrs Point, the terminal creek of an extensive channel network, and Kingsport, a second order creek closer to the mudflats and much larger in size. Measurements included flow velocity measured with Acoustic Doppler Velocimeters and an Acoustic Doppler Current Profiler. Other observations included suspended sediment concentration, sediment deposition and water depth. Comparing the hydrodynamics between the two sites, the tidal prism was larger and velocities were higher at Kingsport, particularly in the creek and on the edge of the marsh surface. Velocities further up the high marsh were comparable between the sites. Starrs Point experienced flow dominance on the ebb tide while Kingsport did not experience as much of a difference in flow magnitude within a tidal cycle. Both suspended sediment concentration and deposition were greater at Starrs Point, indicating that the higher order channel was a depositional environment during the study period. There was a significant difference in sediment concentration and deposition between the creek and the marsh surface at both sites but the difference was much more pronounced at Starrs Point. This work indicates that creeks of different size and channel order can have sedimentation at different rates and different cross-channel variability. The terminal creek is shown to be a depositional environment while the second order channel is a region of sediment advection into the higher order channel network.