ABSTRACT
The chapter briefly describes the current discussion among those in the Netherlands who prefer to build more robust defenses along rivers and towards the coast and those who advocate an approach that allows water to take up more room when needed along rivers and around estuaries. Here, a defense against water would follow a redundancy model. Thus far the discussion is ongoing. The chapter lists the contemporary approaches to water management in the light of the higher winter discharge of the Rhine and Maas rivers and an expected increase in precipitation during the summer months. Starting with the policy to make more room for water along the great rivers and the River IJssel, the chapter presents projects that call for the removal of sediments along the River IJssel and the excavation of the floodplains of the river to store water and prevent floods like the ones that threatened Ijssel River towns in the 1990s.At Nijmegen, a significant river bypass was trenched into the historic floodplain to relieve the Waal during high water. As a forward-looking example, the chapter lists the water plan for Rotterdam, where the city government is looking in all neighborhoods and urban districts for possible spaces to store water. They are finding room on roofs, under streets, in playgrounds and in the city’s parks. The discussion moves to the future of the estuaries that were disconnected from the sea prior to the Delta Works and the creation of the IJsselmeer. What can be deducted from the current literature is that ecological values have become more influential in the 30-year debate about the future of the former Dutch estuaries. The understanding has grown that estuaries, with their tidal rhythm and their gradients from saline to freshwater, are ecologically much healthier than separated and isolated water bodies. The first line of defense for much of Holland is provided by the barrier dunes. They owe their existence to sediment transport from the mountains down the great rivers; a process that started anew with the end of each ice age. The transport was significantly reduced when rivers were regulated. The result is a deficiency of sediments that reach the coast and form the sand necessary to shape the height and width of the dune barrier. To remedy this deficiency, very large amounts of sand are dredged up from the North Sea floor and deposited along the shore to be transported by wind and current in a generally northbound direction. The experiment with so called “sand engines” has been successful thus far. However, it is noted that a massive concrete armature was deemed necessary and completed in 2015 in the dunes at Katwick to secure the Randstad from sea level rise. It is located in the dune barrier’s weakest spot, exactly in the place where the Rhine river used to meet the North Sea in prehistoric times.
