ShoreScape: Nature-Based Design for Urban Coastal Zones

Since the 1990’s the Netherlands has changed its coastal defence system from hard to sediment-based measures, compensating coastal erosion by adding sediment to its sandy shores. In order to keep pace with sea level rise, more nourishments will be needed in the future, including the ‘Building with Nature’ (BwN) technique: large scale nourishments to feed the coastal system for a longer period of time and using natural forces to bring sediment ashore. However, these dynamic nourishments are still in development and put new demands on spatial coastal planning to support dune formation and increase the coastal buffer zone. The objective of this paper is twofold: (1) to discuss how the interactions between the landshaping processes induced by the nourishments and other coastal functions can be improved as stepping-stones to new design principles for integrated coastal planning enhancing BWN processes, and (2) to provide an overview of initial design principles. Two Dutch cases serve to illustrate the land-shaping processes and the involved design principles. The Walcheren case shows a regional design study for the positioning of BwN (mega) nourishments. This mega-nourishment feeds the narrow dune system as an alternative to the current (more frequent) ways of local beach nourishment. By zoning and staging the nourishment and land use, not only coastal safety, but also other coastal functions, such as recreation, waterfronts and ecology can be improved. The Sand Motor is a prime BwN experiment of mega nourishments in the south of Holland. It is now seven years in progress, featuring an accreting shore, new embryonic dune formation and increased beach recreation. The study shows on a local scale how morphological processes and urban use have evolved and how these processes could be altered and integrated in order to enhance BwN fore dune formation to enlarge the coastal buffer against erosion. The case studies show that the regional design and spatial zoning of nourishment dynamics can help to fine-tune BwN with other coastal functions, such as waterfronts and nature reserves. On the local level dune formation can be improved by adjusting the initial nourishment design, urban and ecological layout to the desired sand transport, using natural landscaping mechanisms as design principle. These will be investigated further in the ShoreScape project.