Pre-, During-, and Post- BUDM Hydrodynamic Monitoring at North and South Channels

A BUDM project at the Scotch Bonnet Wetlands, in Stone Harbor, NJ, USA provided a unique opportunity to measure hydrodynamic and morphologic conditions in two marsh channels (North and South) before, during, and immediately after the material placement. The South Channel experienced no direct placement, while low-lying head areas of the North Channel were infilled. Data analyzed in this study include water levels from deployed pressure sensors and an existing United States Geological Survey (USGS) gauge, flow velocities from deployed tilt current meters, wind data from permanent monitoring stations, and bathymetry from field surveys. Pre-placement, the North Channel experienced mean peak velocities of 27.4 cm/s (flood) and 26.2 cm/s (ebb), and mean peak velocities at the South Channel were 22.5 cm/s (flood) and 38.5 cm/s (ebb). Post placement, the North Channel saw decreases in mean maximum velocities to 11.3 cm/s (flood) and 11.0 cm/s (ebb). In comparison, velocities in the South Channel remained similar to pre-placement flood conditions at 24.1 cm/s and had a minor decrease in ebb to 27.2 cm/s. Results indicate that morphological changes caused by BUDM projects can potentially decrease flow velocities in marsh creeks, which could reduce channel erosion. Understanding BUDM can inform other sediment placements and their effectiveness at attaining coastal resiliency and marsh restoration goals.