Gerard Schlooz

Pilot project the Sand Engine; a mega-nourishment
The decision to preserve the sand volume in the coastal foundation led to a yearly need of 1.1
Mm3per year for the Delfland coast, Pekkeriet (2011). The Delfland coast is located between
Hoek van Holland and Wassenaar. From economical and ecological motives, the idea arose to
construct the Sand Engine, a peninsula at the coast of Ter Heijde, to take care of the yearly
need of sand. Currents, waves and wind will spread out the sand from the peninsula along the
Delfland coast assuring the upkeep of the coastline and its foundation.
The Sand Engine, figure 1.1, consists of 21.5 million cubic meter of sand and has a surface of
128 ha. It's located at the coast between Ter Heijde and Kijkduin. The construction began in
March 2011 and finished in July 2011. Over the next 20 years the sand will be spread over a
region between Hoek van Holland and Scheveningen. This will lead to an increase of the dune
area. Expected is 33 ha of new dune area, Tonnon et al. (2009).

Pilot project the Sand Engine; a mega-nourishment

The decision to preserve the sand volume in the coastal foundation led to a yearly need of 1.1

million cube meters of sand per year for the Delfland coast. From economical and ecological motives, the idea arose to

construct the Sand Engine, a peninsula at the coast of Ter Heijde, to take care of the yearly

need of sand. Currents, waves and wind will spread out the sand from the peninsula along the

Delfland coast assuring the upkeep of the coastline and its foundation.

With the construction of the Sand Engine a new situation is originated. Before the construction

the coast between Hoek van Holland and Scheveningen was a straight line that was relatively

stable, after the construction the coastline is curved and changes rapidly in time. It is unknown

what this change will do to the hydrodynamics of the surf zone. This uncertainty is a big issue

for the swimmer's safety, which calls for a better understanding of the new situation.

Research objectives and questions

The new situation lead to this research with the following research objectives:

• What implications on hydrodynamics may be expected due to a convex curved coastline in a wind sea environment.
• A mega rip may be expected due to the curved coastline; Obtain a better understanding in the relevant processes of a mega rip in a wind sea environment.
• Relate the characteristics of the mega rip, in a wind sea dominated coast, to swimmer's safety.

The research questions are:

1. What is a mega rip?

2. Under what conditions may we expect a mega rip at the Sand Engine?

3. What processes are relevant when modeling a mega rip at the Sand Engine, using Delft3D?

4. What are the relevant characteristics of this mega rip for swimmer's safety?

5. What may be expected in the near future due to the curved coastline with respect to RIP currents?