Figure 9.25. Hondsbossche Sea Defense and Hondsbossche Dunes
Note: Hondsbossche sea defense is on the left (before), and Hondsbossche dunes is on the right (after). Source: Courtesy of Rijkswaterstaat
The adopted strategy for coastal management in the Netherlands is hold the line. The Dutch coast is retreating in most places, but by sand nourishment, the coastline is dynamically maintained (hold the line). Along the north Holland coast, the 5.5-km‑long Hondsbossche and Pettemer sea dike (a traditional design) no longer met the safety standards. The following four possible solutions were considered. Three were a traditional approach, and one was a natural (sandy) approach (Figure 9.26): 1. Raise the crest of the dike (traditional approach) 2. Add nourishment to the foreshore (traditional approach) 3. Make the dike resistant to overtopping (traditional approach) 4. Construct dune, beach, and foreshore (natural [sandy] approach) All four alternatives met the required safety standard. The natural (sandy) solution was selected for the following reasons: • Safety. It was the alternative that could be implemented most quickly. Also, sand is a flexible solution that can be adapted in the future, and it gives a high feeling of safety (buildings are far from the sea). • Environment. The design gave the least hindrance to the environment (no interference to the landside of the dike). It created chances for nature and economic development, and it was possible to mitigate effects on nature. • Execution. The sandy approach fits well with other projects in the area to improve spatial quality (for nature and recreation). • Cost-benefit. From the social cost-benefits analysis, this solution turned out not to be the cheapest, but it did deliver the highest benefits (tourism and recreation) compared to the other alternatives.
09 | Beaches and Dunes
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