The coastline of the Rhone delta (90km long) is subjected to predominant coastal erosion (on average, 4m/yr over the last 60 years) arising from structural reasons (sedimentary deficit, very fine sands, energy of the swell).

The spatial distribution of the sectors in erosion/accumulation can be divided into four coastal units. This stretch of coast is greatly influenced by economic, industrial, harbour and touristic activities, which are sometimes in conflict with the protection of the landscape and natural heritage. The management choices are thus very different according to human and economic requirements: either to stabilise the position of the coastline or to accept a moderate retreat.

Major public works are effective and justified on sectors with high economic value, where such structures are necessary to block coastal erosion. However, their effectiveness is limited in time and they can produce negative effects. The choice of less-costly techniques (ganivelles) is effective provided that sedimentary input is sufficient. A number of innovative techniques (rebuilding up of beaches, sedimentary bypassing on river courses…) have not yet been put into application.

• Study area: 90 km ; Sedimentary cell: 4 km
• Type of coast: delta and beaches (with fine sand; D50 =0.2 mm)
• Tidal regime: micro tidal (0,3 m)
• Range of waves : mean Hsig =0,8 m and T = 4,5 s ; annual storms Hsig= 3m and , T :7 s