Text by Mark Voorendt
In a study of the provinces of North and South Holland, the coastal protection of Scheveningen was pointed out as a weak link in the Dutch coastal flood protection line (Visie Hollandse Kust 2050). As a consequence the boulevard of Scheveningen, between the Scheveningseslag and the terminus of tram line 11, was reinforced, in combination with upgrading the spatial quality of this coastal zone. The artistic design was made by the Spanish architect Morales. He tried to revitalise the vanished historical curves in the coast line. It appeared to be possible to incorporate a sturdy dike in these lines, camouflaged, and improve the relation between land, beach and sea. Morales created various levels in the boulevard, which come together at several places, like the Keizerstraat. At other locations, these levels are separated, like near the Scheveningseslag where the car traffic is separated from the strolling public. Figure below gives an impression of the construction of the dike in the boulevard and the curved line after completion of the work.
The technical design wasmade by Arcadis, a Dutch consulting company. The improved coast protection was designed as a ’hybrid’ structure: a combination of a ’hard’ dike with a soft sandy beach and foreshore. The sand volume in front of the dike reduces the wave height and thus limits over-topping volumes to 1,0 l/s/m. Therefore, the crest height of the dike could be limited to NAP + 10,10 m, except for a small stretch near the Seinpostduin (NAP + 12,0 m) and the Schuitenweg (NAP + 8,60 m). The toe of the dike is situated below the level of eroded sand during a design storm. In this way collapse of the dike due to toe erosion is prevented. The revetment on the outer slope (1:3) was calculated to withstand immediate wave attack. The existing beach wall was removed because it was all covered by sand and its influence on the reliability of the flood defence was unknown. Removal resulted in more certainty about the erosion point. This point is now fixed by the dike. Figure below shows some technical details.
The connection of the new structure with the existing flood defence consists of an extension of the dike into the dunes at the north side. These dunes sufficiently resist against erosion to protect the structural transition. At the south side, the dike is curved landward around the loop of the tramway and stretches beyond the erosion point.