Forebanks undervalued

Published: 2 July 2014

A dike with a green forebank is better able to cope with a range of wave heights. Vegetation, such as willows, mangroves and salt marshes, can dampen large waves faster than small waves. As a result, waves of various heights are dampened, so that they are the same height when they reach the foot of the dike.

Adaptive dike can save millions of euros on dike upgrades

Bregje van Wesenbeeck, an ecologist and a specialist in natural water defences with Deltares, will be discussing this valuable feature of forebanks in greater detail at the Understanding Risk conference in London. ‘We can make dikes adaptable so they can cope with changing conditions. That could save us millions of euros in the future on dike upgrades’, she explains.

Design rules for hybrid solutions drafted and validated

Even so, forebanks are hardly included at all during assessments of dike protection levels. In addition to a lack of familiarity with this ‘hybrid solution’, this can also be explained by the lack of design rules. Bregje van Wesenbeeck: ‘That is why we are now working hard on drafting and validating design rules. The next step is to design tools that are easy to use, and that is being done in, for example, the EU project FAST.

As well as providing flood protection, forebanks also have socio-economic benefits

As well as providing flood protection, forebanks also have socio-economic benefits. Maintaining or restoring these areas outside dikes makes the landscape more attractive, drawing more visitors, and creates habitats for fish, shrimps and shellfish.