Coastal erosion France
The coastline of France is 5,500 km along three maritime fronts (1):
- the southern North Sea and eastern English Channel
- the Atlantic
- the Mediterranean
41% are rock headland and pocket beaches (13% are cliffs), 35% are open beaches, 24% are sand flats, mudflats and salt marshes (largely empoldered today). The proportion of these percentages taken up by artificial shorelines is unknown. Artificial shorelines are mainly associated with ports, marinas and reclamation fill. Active cliffs are common along the English Channel and parts of the Brittany coast. Cliff erosion rates vary from <0.08 m/year to >1 m/year (2).
Pure gravel beaches are rare: mixed sand and gravel beaches are more common. Sand beaches are the dominant beach type and are well-developed in association with the coastal dune systems of the southern North Sea and English Channel down to the Somme Estuary, and on the Atlantic and Mediterranean coast. Beaches vary in setting from open to embayed, and occur as both barriers and fringing beaches. Embayed and pocket beaches are very common along the coast of Brittany, the Atlantic Pyrenees, and in the eastern (Pyrenees) and western (Alps) extremities of the Mediterranean coast (1).
Tidal ranges are low microtidal (<0.7 m at spring tides) in the Mediterranean, micro- to macotidal (2-5 m at spring tides) along the Atlantic coast, macrotidal (5-8 m at spring tides) in the eastern English Channel and southern North Sea, and peak to megatidal (>8 m at spring tides) near St. Malo (1).
Reliable statistics are lacking on the actual state of the French coast in terms of stretches affected by erosion, stability or accretion. The situation appears to be relatively well-retrained for parts of the Mediterranean, Normandy and the north. Sediments for beaches, especially those having a significant gravel component, have been derived mainly from cliff erosion. In the Mediterranean, where beaches have been sustained by sediment supply from river deltas, erosion is set within an overall background of lesser river sediment input related to a decrease in the frequency of major floods, catchment reforestation, dam construction and dredging activities since the 1950s. This erosion is likely to continue in the future because of dwindling fluvial sediment supply from river catchments. There has been a drastic reduction of beach width due to the growth of urban fronts (1).
France has no national coastal management strategy. Coastal management is the responsibility of municipalities (3). By law, local communities are allowed to carry out coastal defence works where this is deemed necessary to preserve common interests. Municipalities or communities bear the costs of local defence operations, with the possibility of additional funding by the Regional Council. Exceptions are the coasts adjacent to the three major ports of Marseilles, Le Havre and Dunkirk, which are managed by the port authority. An overall view of management practice has generally been lacking. As a result, the spread of beach erosion has commonly been aggravated by the individual communal efforts lacking a common view of the effects on downdrift sectors of engineering structures implanted in updrift sectors (1).
‘Hard’ coastal defence structures in France are rock armouring and sea walls, groins, and breakwaters. Since the 1980s softer coastal and beach protection methods such as beach nourishments have become more popular and now tend to supersede other forms of beach protection. Beach nourishment in France has traditionally been coupled with the aforementioned ‘hard’ structures, used as supporting measures to minimize sand losses and maintenance (1).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for France.
- Anthony and Sabatier (2013)
- Pierre (2006), in: Anthony and Sabatier (2013)
- Dronkers and Stojanovic (2016)