A Sediment Strategy For Coastal Zone Climate Change Adaptation

Deltares, Netherlands

job.dronkers@deltares.nl
jan.mulder@deltars.nl

Abstract

There is no doubt that climate change will raise the sea level, even if there is quite some uncertainty about when and how much. Along all continental shores, beaches and wetlands will be drowned. One may also expect that extreme water levels will occur more frequently and that they will cause greater damage. Low-lying sedimentary coasts will be most affected. However, these coasts will not remain passive. Like during the Holocene marine transgression, natural sedimentary processes will produce changes in the coastal morphology. Morphodynamics will mitigate the negative impact of a higher sea level at some places, such that the bathymetry keeps pace with sea level. At other places however, morphodynamics will exacerbate the negative impact of sea-level rise by enhancing coastal retreat. The present experience with artificial coastal nourishment learns that we can take advantage of natural coastal morphodynamics to counteract this enhanced coastal retreat. A sediment strategy aims at mitigating the negative impact of sea-level rise by a set of measures that take optimal use of existing natural morphodynamic processes and existing sand or gravel resources. These measures and the underlying conditions are discussed in this paper.