Longshore Variation of Grain Size Distribution along the Coast of the Rhone Delta, Southern France: A Test of the "McLaren Model"

Abstract

Twenty nine beachface samples from the Rhone delta were collected and analysed to assess the application of the sediment transport model devised by McLAREN and BOWLES (1985). According to this model, in the direction of longshore transport, successive sediment samples should become either coarser, better sorted, and more positively skewed, or finer, better sorted, and more negatively skewed. However, the Rhone delta beachface sediments tend to get finer and more poorly sorted in the longshore transport direction, and skewness exhibits no significant trend. The main reasons for the disagreement between the actual transport path along the Rhone delta coast, and that predicted by the model of McLAREN and BOWLES is the fact that several assumptions underlying the model are not valid in the nearshore environment. Therefore, the use of the model in determining transport paths in the nearshore zone is limited.