An Offensive Coastal Defence

In order to protect the Netherlands against a rising sea level and heavier storms there are two options. On the one hand side the dikes can be heightened and strengthened. This is a well-known technique, which is tested and measured in a lot of studies. On the other hand natural processes of wind, water and sea can be used to create an offensive coastal protection.

The latter option is able to improve the flexibility and the resilience ability of the coastal zone. Such a flexible defence can be realised for example in the form of a new row of Wadden islands in front of the existing ones (Alders, 2006; Roggema et al., 2006). These new islands are capable of minimising the heaviest waves in case of a North Western storm. If these islands are realised with a strong protection against the sea they may function as a safe and luxury living and recreation area. Moreover, they create a quiet lagoon, where the circumstances are excellent for developing high ecological values of typical Wadden Sea wetlands. Behind the new islands the existing ones form natural quiet zones amidst an enlarged Wadden Sea. These are the new ecological key areas, where birds and sea animals find protection during storms and where enough food can be found. The third protection layer is the existing sea dikes, which need to be maintained well in order to protect the province of Groningen. These dikes do not or only minimal have to be heightened. Finally, the original brooks of Lauwers, Reitdiep and Damsterdiep can be regenerated and recover their original flexibility and dynamic if the risen sea is allowed to enter these brooks again. Valuable new brackish nature reserves will emerge here (See also Chapter 5, Climate buffers).

The introduction of a new row Wadden island in front of the Northern Netherlands coast has several advantages (Roggema et al., 2006). Sedimentation of sand is stimulated if a quiet lagoon is created. The result of this is that the growth of mud rises equally fast as the rise of the sea level. The sandbanks will stay as high as necessary to fall dry during ebbtide and the existing ecosystem can be kept intact. Moreover, the result of the creation of new islands extends the area of valuable wetlands. The islands protect the land against storms by breaking the waves in an early stage and the islands can be utilised as living area and recreational facility (Fig. 2.18).

Another design for the islands may include the combination of different functions (Fig. 2.19). These islands consist of a basin, which is empty in regular circumstances but may be flooded in case of a storm. These fall-lake functions as a energy producer, using the hydropower when water enters the island and uses wind-energy to pump the water out again. Use of the extra storage during stormy weather may support the protective power of islands. Beside this function these kinds of islands give room to intensive harbour connected industries, which are difficult to implement on land.

Fig. 2.18 An offensive coastal defence for Northern Netherlands (Source: Roggema et al., 2006)
Fig. 2.19 Harbour island in front of the Northern Groningen coast (Source: MUST, 2007)

An island like this may be positioned in the Eemsdelta area up north in front of the Groningen coast (MUST, 2007). This leads to a harbour typology in the northeastern part of the Netherlands: Eemsharbour with green energy and Delfzijl with its green chemicals.

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Renewable Energy Eco Friendly

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