Coastal Hydrodynamics And Transport Processes

The hydrodynamic conditions or processes, that come about from waves transforming over a coastal profile and generating wave set up and longshore currents, will result in movement and transport of the sediments (e.g. sand) present in the profile. This is referred to as ‘’littoral transport processes’’ and is the main subject of this article. However, transport of fine sediments will also be discussed, but only very briefly.

Sediment transport, General

The sediment on the seabed is transported when it is exposed to large enough forces, or ‘’shear stresses’’, by the water movements. These movements can be caused by the current or by the wave orbital velocities or a combination of both, the latter being the most important situation. The relevant parameters for the description of the sediment transport along a shoreline or in a coastal area are therefore the following:

• The wave conditions at the site and the possible variations over the site plus the adjoining areas
• The current conditions as well as the variations of these over the area
• The water-level conditions, i.e. tide, storm surge and wave set-up
• The bathymetry (the depth variations) in the area
• The sediment characteristics over the area
• The sources and sinks of sediment, such as rivers, eroding coasts or tidal inlets

Littoral Transport

Onshore and Offshore Transport and Equilibrium Coastal Profile

Transport of Non-Cohensive sediments mainly by Currents, Tidal Inlets