Future Coastal Defence in The Netherlands: Strategies for Protection and Sustainable Development
Keywords:Coastal management, policy analysis, nature conservation, nature development, sea-level rise
Coastal defence is a major function of the Dutch dunecoast. The dunes are considered to be important, in addition to coastal defence, as a nature conservation area and for recreation and drinking water production. At many places the dunecoast is subject to erosion. Without mitigation measures the erosive trend will continue into the next century and will probably worsen due to the increase of sea-level rise. It will have serious effects on the safety of the inhabitants of the polders and on functions of the dunes. To develop a structural approach to coastal defence management after 1990, the Dutch government commissioned Rijkswaterstaat to carry out an integrated policy analysis study. The period considered was 1990-2090. Several scenarios of sea-level rise were taken into account: 20 (present-day), 60 (expected) and 85 (pessimistic) cm/century. The study resulted in four alternatives for coastal defence: admission of further retreat (W), selective erosion control (S), full erosion control (F) and seaward expansion at relatively weak sites along the coast (E). Implications of these alternatives to safety measures, costs and loss of dune area along the coast are presented. An approach is proposed to integrate traditional coastal defence management with nature and landscape conservation. A method for classifying nature in the outer dunes is given. Five options for a more nature-oriented coastal defence management are discussed. The options advocate the management of the dunes as dynamic systems requiring human activities to retain or regain valuable natural features.