The beach area is highly important (tourism, ecological, economic and social reasons) and, with its high population density, the coast of Zeebrugge, Knokke-Heist, must be considered as being at high risk.

Due to the combination of wave-induced on- and offshore transport with the longshore tidal drift, structural erosion of the Flemish east coast occurs. The seaward extension of Zeebrugge harbour in the 1970s (to a distance of 3,5 km from the coast) cut the easterly longshore tidal flow and locally disturbed the morphological equilibrium.

Due to the erosion, the seawall, which protects the hinterland from flooding in combination with the dune belt, is under wave attack and can be damaged. A rehabilitation of the natural sea-land environment, new technical opportunities and political emphasis have meant that, since the seventies, preference has been given to “soft”, eco-friendly measures (beach nourishment) instead of hard measures.

The measures taken have created a wider beach at Knokke-Heist and the seawall ensures the safety of the people and investments in the coastal hinterland. However, new measures are needed to restore the beaches for recreational purposes. Nourishment is effective in preventing the coastline from receding, but it is not a permanent solution, in fact, during heavy storm surges a great deal of erosion can occur in a short time.

• Study area: local scale
• Type of coast: beaches with sand (D50=0,15-0,30 mm).
• Tidal regime: macro tidal (3,5 -5 m)
• Wave Climate : wave short crested because of shallow seas and short fetch.
• Other: tidal gully “Appelzak”, wind set-up ( water elevation up to 2 m)