The series of storms that the Atlantic arc faced during the winter 2013-14 hightlighted the needs and the interrogations about the efficiency of port defences against the sea.The phenomenon observed in 2013 has been more intense than the previous years.
The port defences facilities (dykes, piers, breakwaters…) are generally adapted to boatyards and docks protection and to absorb ocean waves from storms that happen at least every 30 years and more frequently every 50 years.
Otherwise, the location, the orientation and the quantity of these facilities are decided thanks to studies on the main directions of winds and waves. So, regarding the costs to implement such infrastructures, some ports do not benefit from an optimal protection.
In order to anticipate and limit eventual damages to goods and people in the ports, and also to answer globally to the demands of ports stakeholders, it could envisaged to launch a global reflexion on the effectiveness of port defences against the sea. This work could ascertain the necessity and the feasibility of the implementation of a working plan lasting several years.
1) Current risks analysis : Inventory of damages caused by storms within the ports of identified partners The recurrence of damages and their importance need to be searched on a sufficient timeline in order to be relevant and to provide information elements that could enable a prioritisation of projects. Some benchmark on maritime archives could bring the necessary information. This phase will also highlight the points to pay particular attention to.
2) Coming risks analysis Although the impact of the global warming cannot be precisely measured yet, it should change the storm process. Indeed, the modification of the development of waves and the difference between expected sea level thanks to tidal mechanisms and real sea level on one hand, and the sea level rise on the other hand have direct impacts on our environment. These modifications are especially to be crucial as the seabed is not deep such as in Brittany where the coasts face break waves. these conditions, a risk analysis on the goods and persons should be done on each port in order to provide all the information needed to prioritise interventions. Thanks to this analysis, the relevance of the development of prevention tools for natural disasters on ports (information, raising awareness, staff training, intervention process…) could be studied.
3) Inventory of implemented studies and projects
4) Inventory and estimation of feasibility study to be implemented
5) Proposal of possible solutions The protection of goods and persons from the sea in the harbours cannot be summarised to the effectiveness of port infrastructures, especially as the costs of the restoration work are exorbitant. So, as for the risk prevention plan, a reflection on the prevention measures at the port scale could be lead in order to protect the goods and the persons from the sea.For example, these measures could lead to a modification of the exploiting conditions within the harbour (no parking zones on exposed areas for vehicles and boats, development of unbuildable land, moving activities when occupation contracts are negotiated…). Then, warning and information procedures to the customers and users could be implemented to inform fishermen and yachtsmen they have to move theirs boats to sheltered locations (on land or in port basins). Regarding the reinforcement or the creation of protection structures, different technical processes can be highlighted. Innovative solutions such as “green” dikes that enable the development of the biodiversity could be studied, notably regarding the environmental and landscape constraints on some harbours.
6) Comparative analysis of différent solutions A comparative analysis (legal and environmental constraints, value for money, disadvantage, efficiency…) between different solutions could enable a ranking of envisaged measure to shape a multiannual action plan Main deliverables: Studies, assessment, exchange of best practices, new transnational innovative solutions and strategies.
Atlantic arc (including the Channel)