A new flood defence with its own built-in car park

The village of Katwijk aan Zee lies on The Netherlands coast, halfway between the Hook of Holland and Ijmuiden and at the mouth of the Oude Rijn. There is already an existing flood defence running right across Katwijk protecting the village and area behind, right through to Leiden around 8km inland.

Part of Katwijk, however, lies outside of the flood defence and therefore unprotected. The structure also too low to cope with a severe storm. One solution would be to raise the defences but this would result in a number of buildings being lost and also change the character of the village. The decision was therefore taken to build a new flood defence actually on the seashore with a row of dunes incorporating a reinforcing dike.

A feature of the region’s coastline is its pristine beaches, making Katwijk a magnet for visitors, particularly during the summer season. The village can often be overwhelmed by visiting cars parking along the boulevard and obstructing sea views. This led to the idea of building a car park inside the flood defence itself. The project is unique in the Netherlands.

The new sea dike will be built using the existing row of dunes between the boulevard and beach. The dune area itself will be increased in size, built where the beach was, a new beach created through sand supply. As the dunes will absorb the first impact of severe storms or high water, the dike does not have to be too high. Being integrated into the coastal landscape in this way, all that will be seen from the beach will be dunes and from the boulevard only dunes and the sea. The car park will be constructed on the Voorstraat against the dike which (along with the dike) will be under a dune. Cars currently parked along the boulevard will therefore disappear from sight.

Construction of the Katwijk Coastal Structure is already well underway, work to create the new beach commencing in October 2013 and building of the dike in December. Completion of the project is scheduled for the end of this year, with access to the beaches being provided as normal for the coming summer season.

The project is a partnership between the municipality of Katwijk, the Rijnland District Water Board, the province of Zuid-Holland and Rijkwaterstaat (the executive arm of the Ministry of Infrastructure and the Environment). It is also part of the second High Water Programme in which substandard flood defences are being strengthened in 89 places.

By Peter Barker