A breakthrough with multifunctional unbreachable embankments

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Climate change makes the Netherlands more vulnerable to flooding but limited budget is available to invest in Dutch flood protection. The solution: maximise the safety for every invested Euro. Unbreachable embankments are successful in reduction of fatality risk and damage risk, without being much more expensive than conventional embankment designs.

An unbreachable embankment is an over-dimensioned, robust embankment which is so strong that the probability of total collapse and flooding is virtually zero, even when the flood level temporarily exceeds the level of the embankment itself. An advantage of unbreachable embankments is that additional functions can be accommodated which may bear part of the cost.

If unbreachable embankments are such a smart investment, why are there so few in the Netherlands? Deltares identified the causes, by analysing 10 cases where multifunctional unbreachable embankments were considered. Research by intern Mallory Tettero showed that the assessment tools are the main cause of difficulty with implementation. Funding also causes difficulties concerning implementation because it decides whether reinforcement will take place or not, and it leads to ambiguities in prioritizing of reinforcement works. The institutional organisation proved not to pose explicit problems but it did show the importance of legally recording and clear defining of the responsibilities.

Based on the results of this study the implementation of unbreachable embankments could be enhanced by giving attention to revising the assessment tools because these turned out to be the main barrier for implementation. Deltares is commissioned with delivering new assessment tools for the next assessment round. The new assessment tools are still under development , but it seems that more flexibility will be implemented concerning assessment of innovative embankment designs.

Full report: 'A breakthrough with multifunctional unbreachable embankments' by Mallory Tettero.

Literature
    • Bruijn, K.M. de, Klijn, F. & Knoeff, J.G. (2012) Unbreachable embankments? In pursuit of the most effective stretches for reducing fatality risk, FloodRISK 2012, 901-908
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      medegebruik van de waterkering. Beantwoording signaleringsvraag #5 van de Deltacommissaris. Delft:
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    • Klijn, F., Kwadijk, J., Bruijn, K. de & Hunink, J. (2010). Overstromingsrisico's en droogterisico's in een veranderd klimaat. Deltares
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    • Vellinga, P., Marinova, N. & Loon-Steensma, J. van (2009). Climate-proofing the flood protection of the Netherlands. Netherlands Journal of Geosciences , 88 (1), 3 – 12