Better view of future water safety

Future water safety can now be calculated. For one, two and even three meters of sea level rise. And so it is also possible to see where the weak spots are. Where is the dune too narrow? Where is there a weak spot in the dune through which the sea eventually reaches the hinterland? These calculations can be made over and over again, with the outcome depending on the growth of the dune massif. The future weak spots have now been Map and will be addressed in the coming years. For example, beach accesses will be raised and areas in the dunes that are too low will be addressed.

Fewer beach construction moves

These new insights and analyses are good news for some of the entrepreneurs along the beach. Until recently, the Water Board wanted to maximize dune growth everywhere along the coast. So beach pavilions that prevented sand from blowing through had to move by definition. Now that it is possible to better calculate water safety and the development of the dune massif, it can also be decided that in a specific spot dune growth is less relevant. "If the dune is already high and wide enough, perhaps additional sand is not necessarily needed," explained Arnold Langeweg, portfolio holder for water safety. "We can now consider per pavilion whether relocation is necessary." That, incidentally, may still prove necessary in the future, especially for narrow dune interventions near built-up areas. "Then we don't have a general story but a specific story of why water safety should be promoted there. I assume entrepreneurs will understand that." 

Resilient coast

All the analyses, calculations and permit procedures have resulted in a renewed strategy to manage the coast: 'Look at a Resilient Coast'. Langeveld: "We can now better 'look into the future' and let other stakeholders look along so that we can come up with solutions together. This will create a more shared sense of responsibility for the water safety of our beautiful coast." 

Interactive viewer

HHNK has developed an interactive viewer so that nature managers, entrepreneurs and, for example, civil servants from provincial and coastal municipalities can see for themselves how far the sea will rise if the sea level rises by one or two meters. Although this is a static image, as if nothing changes, the data are constantly being updated. Therefore, it can also be seen whether the dunes show high dynamics or not. High dynamics mean that there is a lot of room for dune growth: in those places the water safety situation will improve considerably. 

Sea level rises, dune grows

Because as the sea level gradually rises, so do the dunes. And with that, the hinterland is again better protected. Sand blows from the beach into the dunes and so the dune massif grows. This does not happen entirely spontaneously. To prevent the Netherlands from shrinking due to an eroding coast, Rijkswaterstaat has been maintaining the basic coastline since 1990. This is done with sand nourishments: large quantities of sand are deposited just off the coast. This sand is carried along the beach towards the dunes, creating higher, wider and therefore more massive dunes. And sometimes - during heavy storms like the recent Amy and Benjamin - the dunes break off and the sand disappears into the sea. Some of that sand will wash up again. 

Building with nature

Sand replenishment therefore keeps the basic coastline in place, and also ensures dune growth. And nature is helped even further by topping off the first row of dunes, for example, so that the sand can indeed drift through and not get stuck in front. Cracks in the dunes spread the sand even further, as do drift pits. This is called building with nature, because with human intervention nature does its work.

More information can be found on the Management Strategy page, background on the Sandy Coast page.