The Shoreline between Nature and Society, a Changing Heritage - Vulnerability of Coastal Ecosystems and Adaptation - page 176

subject to storms. The media coverage of these exceptional
catastrophic phenomena also helps in managing, in a more intelligent
way, this coastal strip exposed for millennia to the action of the
waves. It has also made us realize in the past few centuries that getting
too close to the sea is not risk-free especially given the sea level rise
we have observed for more than a century.
With various uses of a fragile and highly dynamic space and with
growing pressure, competing human activities of all types arise. Can
we regulate without prohibiting and, if prohibiting is unavoidable, can
we do so with the consent of all the stakeholder groups? In other
words, can we protect coastal human settlements and the coastal
environments from human covetousness? It is a major challenge that
requires an integrated management approach of coastal zones.
5.2. Coastal dynamics
The more settlements have moved to coastal areas, the more
sensitive these areas have become to changes in the coastline. While
the postglacial sea level rise was coming to an end, the residents of the
Gulf of Morbihan had to move their settlements further inland, which
we are reminded of by a few megaliths immersed by a several meters
depth. Nowadays, the same observations are made everywhere,
especially as the exposed settlements are numerous and as the coast
had to be barricaded by flood defense walls to protect its residents
from the waves. Coastal erosion is a natural process: a cliff is a perfect
vestige of erosion, and this movement is irreversible. It can be seen
each year between Criel-sur-Mer and the Somme Bay, when
comparing it with photographs taken successively since the end of the
19th Century that, roll after roll, dozens of meters have fallen into the
sea. However, in spite of this observation, things are more
complicated as they have developed within a real system that should
be explained.
5.2.1. The morphogenic coastal system
In this system, five factors play a role [MIO 09] (Figure 5.1).