Coastal protection policy in the Netherlands

Abstract

The 350 km long Dutch coast along the North Sea is characterized by alternating coastal stretches of accretion and erosion resp. resulting in seaward and landward displacement retreats of the shoreline. Places of accretion and erosion also vary in time. Behind the dunes are low lying polders (very often with a ground level even below the low water line), in which millions of people live. The coastal erosion endangers the strength of the dunes as a sea-defence. Erosion of narrow dunes (at some places the dunes are less then 200 m wide) can therefore not be permitted in the Netherlands. At 40 km of coastline the dunes have no more than 10 m extra width available to cope with the erosion problem. A yearly erosion of only 1 m/year causes big problems within a few years. Since life in the Netherlands is so highly dependent of the quality of the coastal defence, structural solution for this problem must be developed and carried out. In the past the only way to attack the erosion problem was to build groins. Several sections of the Dutch coastline are defended with these constructions (see figure 1). Evaluation of the efficiency of groins as tools for erosion was not stopped by these constructions. More recently (last decades) nourishment of sand beach and front dune has been practised to compensate for the loss of sand dune to erosion.