Sandbar-beach-dune dynamcs of a sandy nourished coast in Noordwijk, The Netherlands

Abstract

Coastal areas are one of the most heavily populated locations on Earth. With a growing population on the landward side and the predicted sea level rise on the seaward side the flood risk increases. To protect the coastal areas, several measures have been implemented. In Noordwijk, the Netherlands, beach and shoreface nourishments are implemented since 1998. The effect of these nourishments is studied on the basis of two factors; sediment transport pathways and sandbar characteristics. Large-scale sediment transport pathways have been found from the shoreface nourishment to the outer bar in the coastal system of roughly 30-50 m3/m/yr. These shoreface nourishments decay within a timeframe of approximately 7 years. This leads to an increase in the outer bar height of on average 0.5 m. The inner and middle bar show no significant change in average bar height. From the bar position, the bar migration was calculated. The bar migration shows a stall after the implementation of the first nourishment. The natural dynamics of the sandbars showed a bar cycle of about 4 years. This has increased to more than 10 years. Since the bars stopped migrating, no new sandbars are formed at the coast. The sandbars stop migrating offshore and remain roughly stationary for the remainder of the study period. The bar length showed no significant change between prior and after the implementation of the nourishment.