Resuspension and Advection as Sediment Transport Processes in the Elwha Delta Nearshore Environment

Abstract

The largest dam removal project in U.S. history began on the Elwha River in 2011. A large quantity of sediment was expected to enter the marine environment, but where this sediment would end up and how it would get there were unknown. This study investigated currents and sediment transport at a study site offshore of the Elwha Delta over two winters during the dam removal process. Trends between Acoustic Doppler Current Profiler (ADCP) data and oceanographic conditions were examined. Suspended sediment concentrations at the study site were obtained by calibrating ADCP backscatter data, and were found to be most strongly correlated with river discharge. These data indicated that advection was the primary mechanism of sediment transport at the study site. Currents were found to be predominantly eastward, indicating the direction of advection. This study provides a foundation for future work examining the transportation of sediment in and around the Elwha Delta, and how this transport will impact the area in the future.