Adaptation strategies to maintain dunes as flexible coastal flood defense in The Netherlands

Abstract

Coastal dunes play an important role in coastal defense along sandy shorelines of the world. The majority of the shorelines experience erosion and this erosion is expected to accelerate under anthropogenic climate change and subsequent sea level rise. This paper investigates the impact of climate change, sea level rise and current management for coastal dunes in the Netherlands. Furthermore the paper discusses the implications of climate change projections for adaptation strategies into the future. Recent climate change scenarios for the Netherlands highlight rising temperature and accelerated sea-level rise. Their combined effects on dune-building processes are expected to be manifested through an increase in erosive forces at the expensive of accretive forces. In the Netherlands, a negative sand balance and inland migration of the beach-dune system has been successfully counteracted in the last decades through the application of sand nourishments. These have enhanced accretion on the one hand and limited erosion on the other hand. Generally, coastal protection has improved despite rising sea levels. Important preconditions that make this sand nourishment strategy possible are: a readily available sand resource that makes exploitation technically and economically feasible; a sound monitoring system supported by solid science; political consensus and a good institutional structure to implement the strategy. In the Netherlands, the necessary preconditions are already in place to successfully adapt to sea level rise. Given the expected accelerated rise in sea level and its potential effects on the dune-beach sediment balance, the annual sand nourishment will need to be intensified to ensure the preservation and integrity of the coastal zone.