Mirt study + Multi-layer safety
Towards an adequate solution for flood protection in Marken by finding an alternative way for dike reinforcement. The usual fifty years reinforcement term will be abandoned and also measures beyond the dikes are possible (multi-layer safety).
The primary flood defence work protecting Marken does not comply with the applicable standards in certain areas. The reinforcement plan that was developed initially was not supported by the stakeholders due to the space taken up by the plan and the effect on the landscape. Rijkswaterstaat, therefore, decided to look for a different, better and appropriate solution.
Five flood protection measures on the island of Marken
Five flood protection measures were developed on the island of Marken. Dike reinforcement is always the basis (layer 1 of multi-layer safety), complemented with spatial measures beyond the dike (layer 2) and measures increasing the action perspective in the event of a flooding (layer 3). All solutions relate to the ‘Marker waarden’, the current qualities presented in the ‘Gebiedsatlas’.
The ambition was to develop solutions defining the flood risk management tasking and to improve the spatial quality on Marken. To that end, the area and its history have been examined in detail, the residents’ knowledge has been utilised and engineers and designers have closely cooperated.
The first solution consists of a gradual strengthening of the quay, every 12 years. Therefore the dike does not need to be heightened extra in order to compensate for subsidence of the dike. The dike on Marken is rather sensitive to this due to the specific soil profile of clay and peat. Consequently, the dike can remain lower and more compact in line with the current qualities.
In this approach the current quay will be replaced by a new one and will be built beyond the dike. Firstly, the subsurface will be improved to ensure the dike is less sensitive to setting. For the Rozewerf, a customized solution was developed together with the residents. The old quay will be maintained and a harbour will be built serving as a transitional construction between the old and the new quay.
This approach proposes the construction of an embankment on the Markermeer side of the island. In this way the wave run-up will be inhibited as a result of which the crown of the dike will be longer. Also, reference is made to the 17th century historic outline of the island. The embankment contributes to water quality improvement and the ecological value of the Markermeer as a whole.
This solution will increase the resilience of the south quay to water running over the quay. Therefore, the quay does not have to be as high as it would have been in case regular reinforcement was applied. The water running over the dike will be collected in the southern part of the island where buildings are generally elevated.
Until the closure of the Zuiderzee in 1932, all houses on Marken were built on elevated yards and poles. After 1932 houses were simply built at ground level. In this long term strategy new meaning is given to the historically elevated homes by building all new houses in Marken according to the water robust strategy.
From the above solutions, three have been chosen at an administrative level. Currently, these solutions are further elaborated and fine-tuned in a MIRT study after which a preferred alternative will be chosen.
