Longshore Sediment Transport Measurements on Sandy Macrotidal Beaches Compared with Sediment Transport Formulae
Résumé
In a context of global climate change, local sea level rise could affect the different coastal processes as erosion, transport and deposition which are responsible in maintaining the coastline. The study of sediment transport processes is one of the key for a better understanding of the coastal evolution which is needed for effective design of coastal engineering or to protect anthropogenic activities and population from marine submersion. One of the main processes that control coastal evolution is sediment transport. A number of studies have been focused on this topic, but they were mostly restricted to micro- to mesotidal beaches [1-3] and field investigations on sandy macrotidal beaches appear to be more limited, notably because these environments are less common along the worldwide coastline [4]. Only a few studies have been conducted for quantifying sediment flux on macrotidal beaches [5, 6] where sediment transport results from the complex interactions of tidal currents with longshore currents generated by obliquely incident breaking waves, this complexity being further increased by the large variations in water level that induce significant horizontal translations of the surf zone. Although a number of studies were recently conducted on the morphodynamics of the barred macrotidal beaches of Northern France [7-12], relatively little effort has been dedicated to measuring longshore sediment transport on these beaches, even though it is largely recognized that they are affected by significant longshore transport that plays a major role in the morphodynamics of the intertidal zone [10, 13]. Apart from some attempts to make estimates of longshore sediment transport from fluorescent tracers [10, 14-16] and to infer transport directions using grain-size trend analysis techniques...