Alternative strategies for adaptation of the coastal protection along the Belgian coastline were evaluated. Possible measures to adapt sea dikes in coastal towns as well as dunes and beaches being the natural coastal defences of the sandy Belgian coastal zone were developed for scenarios of climate change with a time horizon untill 2100. The different adaptation measures were evaluated by a combination of risk calculations (functional assessment) and MCA (multi-criteria analysis including a simple CBA).
It was shown that a wide range of direct and indirect secondary effects of climate change related to coastal protection can be identified. Further it was clearly demonstrated that the flood risk calculations are an excellent tool to assess the impact of the most important secondary effects of climate change (damages and victims). The most important primary effects of climate change that increase flood risks are sea level rise and increased storminess (higher wind speed and higher wave conditions).
One concluded that the most effective measure to maintain coastal safety in Belgium consists of strengthening the existing coastal defence line of dunes, dikes and beaches. Investing in strengthening the existing coastal defence line can provide a solution avoiding an increase of the flood risks due to climate change, but additional research into non-structural measures could lead to an increase of efficiency and thus contribute to, along with investments in strengthening the existing coastal defence line, in a most efficient mix of measures of coastal flood risk management. Non-structural measures one proposes to further investigate are the development of specific contingency plans for flooding by overtopping waves, the strengthening of buildings so they remain structurally stable under the hydraulic impact of overtopping waves and the adaptation of licensing procedures with respect to coastal safety against overtopping.
The conclusion of the research supports the current policy of the Flemish Government to ‘grow with the sea’ by mainly nourishing beaches and other measures to strengthen the existing coastal defence line, as implemented in the Master Plan Coastal Safety 2050. The research results showed that this adaptation policy is feasible to implement even in the case of an extreme climate change scenario of 2 m sea level rise untill 2100. However, an improved adaptation strategy for the Flemish coastal protection would be to combine 1) strengthening the coastal defence line with 2) non-structural measures to reduce the consequences in terms of damages and casualties caused by a coastal flooding by overtopping waves.