The entire Wadden Sea was recently added to the UNESCO World Heritage List. It ranks among the world’s most important wetlands and has unique natural values. The area is also of major importance in terms of flood risk management. The outer deltas, the Wadden islands, the flats and the foreshores (salt marshes) together protect the northern coast of the Netherlands.
The point of departure in the flood protection preferential strategy for the Wadden Region is that the important values of the Wadden Region are maintained by opting for measures that are as ecological as possible. The focus in the years ahead will be on fleshing out the strategy. The region will explore opportunities for an integrated approach to the measures. The Delta Decisions and the Decision on Sand constitute the framework in this regard.
The long intertidal zone in the shallow Wadden Sea (mudflats, salt marshes, and channels) constitutes a buffer against the high waves of the North Sea. Without this buffer, the flood defences along the mainland and island shores would have to be stronger and higher. Currently, the intertidal zone of the Wadden Sea already requires additional sand because of the rising sea level. If the rise in sea level accelerates, the intertidal zone may no longer be able to keep pace and the buffering effect will be reduced.
In addition, the some one-hundred-kilometre long stretch of flood defences along the mainland and island shores of the Wadden Sea does not provide the desired level of protection. Moreover, some sections of the flood defences need to provide a higher level of protection due to the presence of the gas hub. A final important issue is rendering the dykes earthquake-proof.
Preferential strategy with three elaborations
A preferential strategy has been drawn up for the Wadden Region, comprising three elaborations.
The aim of the preferential strategy is for the intertidal zone to continue to grow along with the rise in sea level. This is achieved by sand replenishment. It appears that, in terms of flood protection, until 2100 no sand replenishment will be required in either the Wadden Sea itself or in the Eems estuary; nor is this desirable in terms of ecological value. For the time being, sand replenishment along the North Sea coast of the Wadden Islands (on the coastal base) and possibly on the outer deltas will suffice. Pilots and monitoring (“learning while working”) will show whether the sand will be transferred to the mudflats and salt marshes of the Wadden Sea naturally, and in good time. This is done in the context of the Coastal Genesis II research programme launched by Rijkswaterstaat, which provides insight into the operation and future changes of the sand system.
The preferential strategy for dyke improvement involves an area-based and integrated approach. The focus is on modifying flood defences in line with area developments, and creating added value for functions like Nature, recreation, and the regional economy. Almost everywhere along the mainland shoreline, this can be achieved by implementing innovative dyke concepts, such as wide green dykes, multi-functional dykes, and dykes that can withstand overtopping. The three district water boards, Wetterskip Fryslân, Noorderzijlvest, and Hunze en Aa’s are examining these innovative flood defence concepts in pilots within the Wadden Sea dykes general exploration. The Noorderzijlvest district water board is already implementing innovative dyke concepts in the Eemshaven-Delfzijl dyke improvement section.
Together with knowledge institutes and the security regions, Rijkswaterstaat and the island municipalities are working on an integrated flood risk management strategy for each of the Wadden Islands. The strategies deal with sand replenishment management, dynamic coastal management, salt-marsh development, innovative dyke concepts, and disaster management. The potential impact of a flood on the areas outside the dykes will be reduced by explicitly taking flood probabilities into account in spatial (re)developments. The collaborating islands and the security region will bear primary responsibility for the execution of the strategies.
Collaboration in the implementation
Within the Delta Programme, the implementation of measures in the Wadden Region is coordinated in the Wadden Region Delta Programme Administrative Consultative Body and the Regional Consultation Committee on the Coast.
Delta Programme 2017
To view the progress made in this area, click here: Wadden Region in Delta Programme 2017.