SEDIMENT TRANSPORT IN RESPONSE TO WAVE GROUPS GENERATED BY HIGH-SPEED VESSELS

Abstract: Suspended sediment transport dynamics occurring at relatively short time scales under super-critical wave groups created by moving high speed vessels are investigated by means of field measurements and the application of numerical models. Examples are provided from a variety of different environments, including predominately sandy beaches in low energy estuarine and fluvial settings. Model simulations combining the hydrodynamics of the wakes with steady currents and a sand transport model provide results that are largely consistent with field measurements and observations of the suspended load fraction. Wakes re-suspend sand in the nearshore that would otherwise be immobile and move it incrementally offshore and alongshore, eventually into deeper water where stronger ambient flows (tidal or fluvial) can transport the sediment. Super-critical wakes from high speed vessels have a tendency to cause offshore transport of sand-sized sediment leading to beach flattening while their sub-critical counterparts often lead to beach steepening