Nearshore Placed Mound Physical Model Experiment: Fid-Bau Portal

Nearshore Placed Mound Physical Model Experiment

This technical note describes the migration and dispersion of a nearshore mound subjected to waves in a physical model. The summary includes recommendations for nearshore placement of dredged material. This technical note is the first in a series discussing the physical model experiment and guidance for nearshore mound placement. Subsequent technical notes will discuss the migration of tracer material in a physical model and mound migration of dredged material at Brunswick Harbor, GA. The U.S. Army Corps of Engineers continues to seek opportunities for the beneficial use of dredged material. Frequently, Corps dredged material management plans include offshore placement of dredged material from channel entrances and ebb shoals. This often removes material with a high sand percent from the littoral or regional system. Maintenance dredged material from these areas is generally not considered beach quality (>88 percent sand), but often includes approximately 60-80 percent sand. Placement of dredged material in the nearshore permits natural winnowing/separation of the fine and sand particles. Nearshore mound locations, material, and configurations must be chosen judiciously to assure that the mound does not negatively impact the surrounding environment and that material remains in the littoral system and nourishes the beach. The DOER program has supported a series of physical model and field experiments intended to assess consequences of nearshore placement of the dredged material. This technical note discusses physical model experiments on local migration of a mound at the edge of the surf zone. Although nearshore mounds are generally placed outside the surf zone, these same locations are within or at the edge of the surf zone during storms. Storm events are the predominant transport interval for nearshore mounds.