The Sand Motor pilot after five years: building with nature on the Dutch coast
Published: 14 September 2016
The Sand Motor and protection
The development of the Sand Motor is helping to widen the coastal zone and it is progressing as expected. The sand remains in the area of the Delfland coast, nourishing the coast so that the sand is not needed that would otherwise have to be brought in for maintenance in the coming decades. In the meantime, the coast now provides better protection and it is more attractive. At present, the Sand Motor is supplying sand to a five-kilometre stretch of coast and that will be lengthened as the Sand Motor continues to spread. All this is being closely monitored. Surprisingly, dune growth in the first four years was slower than expected, probably because the sand has to travel a relatively large distance to the dunes and because it first has to cross the lagoon and the dune lake, which have captured a lot of sand in the last five years. The dunes are expected to form faster as soon as the lagoon and the dune lake have filled up more with sand.
Bathing in sea always involves risks. Those risks can be exacerbated near the Sand Motor because of the local changes in the currents. The emergency services are well prepared. Deltares developed a special smartphone app that shows the currents and tides around the Sand Motor.
New nature on the coast of South Holland
Precisely because of the dynamic interaction between water, the sea, winds and tides, the Sand Motor has become an appealing nature area. However, it is not yet possible to say whether this one-off major nourishment operation is better for nature than the standard programme in which sand is deposited on the coastline about every four years. The Sand Motor has not yet been in place long enough and a longer period of monitoring is still needed. The lagoon has added a new habitat to the South Holland coast, with more different benthic species, an important source of food for birds.
The number of plant species and locations where they grow is increasing. They include characteristic sand couch and marram grasses, which are protected by international agreements signed by the Netherlands. A particularly striking development is the abundance of aquatic plants in the dune lake itself.
The monitoring of the Sand Motor will continue through to 2021. Rijkswaterstaat is leading the effort. In 2021, there will be a solid scientific evaluation of the Sand Motor concept because we will then have a firmer understanding of how the Sand Motor works.