Online tool visualises effects of sea level rise on dunes

Published: 18 September 2019

Marieke Eleveld, a coastal expert at Deltares, has presented a new tool to dune and coastal managers. It provides a picture of the interaction between coastline management and dynamic dune management in response to sea-level rise or a severe storm. The tool is part of the three-year EU project ENDURE, which studies how the climate resilience of dunes can be enhanced using natural processes.

In recent decades, research on the interaction between the sea and the coast has mainly stopped at the foot of the dunes. The new tool goes a step further and also shows the effects of sea level rise on the dunes. Dr. Eleveld believes this is needed to ensure that dunes will grow in line with sea level rise as a way of coping with climate change.

More certainty about the condition of the dunes as the sea level rises

The foredune, the first row of dunes facing the sea, has benefited from beach nourishment on the Dutch coast in recent decades. The wind has deposited some of the sand on the dunes, which have increased in size as a result. Traditionally, these dunes have been stabilised using marram grass and the sand was prevented from affecting the dune area as a whole and rejuvenating it naturally. Dune managers are now more interested in dynamic dune management with the aim of maintaining the vitality and health of the dunes. Drifting sand enhances the landscape and the natural values of the dune area. But the question is to what extent the dunes can cope with rising sea levels. The tool allows for an assessment of what is left of the first row of dunes after a given rise in the sea level, storm surges and wave build-up, and whether a shift in the coastal regime is to be expected. It helps dune and coastal managers to think about possible ecosystem-based, climate-resilient solutions in the dune areas they manage.

Online tool

The ENDURE tool can be found online. It combines general morphodynamic concepts such as Bruun’s Law and the Sallenger Storm Impact Scale with wave and storm surge reanalysis data (ERA5 and GTSR) to illustrate possible future scenarios for dune coasts. The tool has been used on a number of sections of the Dutch coast. ‘The important thing now is to allow stakeholders to test the tool and provide us with feedback,’ says Dr. Eleveld. ‘We also want to expand the tool by using profiles from other sandy coasts in, for example, Belgium, France and Great Britain. My dream is that dune and coastal managers will use the tool to discuss the possibilities – and impossibilities – of a resilient coastal and dune area.’

An scenario example for sealevel rise effects in the ENDURE-viewer

Sand dunes as an adaptive, living seawall

ENDURE is a three-year INTERREG programme that investigates how coastal dunes can be optimally used as adaptive, living sea defences. The project is co-financed by the ERDF through the Interreg 2Seas programme.