Bridging the dike

Abstract

The Dutch sea water level raised with 24cm over the last 128 years. From a linear increase, we can see an increasing trend since the 1990s. According to recent scientific research, the sea level in the Netherlands will rise 1 to 2 meters by 2100 with a maximum global warming of 2 degrees Celsius. With a temperature rise of 4 degrees, the North Sea water level will rise 3 meters. At the end of the next century, the rise can increase up to 8 meters. This project focuses on the Wadden Sea, one of the last remaining large tidal areas where the forces of nature are free to do as they please. It is the last of the authentic nature in the Netherland and is essential to millions of birds and fish. The whole Wadden Sea area, which stretches between Den Helder in the Netherlands and Esbjerg in Denmark, was declared a UNESCO World Heritage Site in 2009. Along the coast of the Northern Netherlands, salt marshes were created outside the dikes through the deposition of sand and silt with a spontaneously established vegetation on them. The plants, such as sea lavender, samphire and sea aster, are resistant to the regular flooding by salt tidal water. Salt marshes are one of the few Dutch landscapes of very great international significance. Salt marshes can play a role in protecting coastal regions from flooding. These intertidal zones are delimitated by wooden barriers created by man in settling fields, in order to reclaim land from the ocean. With the tide come sediments that are then held back by the wood enclosure as the water retreats. Salt tolerant species then stick to the mudflats making it more stable and bringing oxygen into the soil for regular plants to grow in these coastal ecosystems. The project therefore includes a territorial intervention: environmental engineering for coastal protection, a landscape Intervention: increase accessibility of the site, and a building intervention: offshore cabins inserted into the primary structure. The tidal area can be saved by the same forces of nature that make it unique: sedimentation can potentially be increased at the same pace as sea level rise, with help of low impact and low cost brushwood dams. With salt marshes breaking the waves, the impact of incoming seawater is muted, it promotes the wealth of species, and retains sediment. As a result, the marshes can grow with rising sea levels. The eroded brushwood dams from earlier times can be rehabilitated to reclaim land in front of the dike. The dams are extended into a floating boardwalk, which unlocks the engineered intervention as common ground. Offshore cabins are inserted into the primary structure on every intersection, overlooking the different landscapes. This increases attractiveness of the land in front-, on- and behind the dike and makes it better accessible from the Frisian hinterland, despite the sea level increase.