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.

Kansen voor meer natuurlijkheid in Natura 2000-gebieden

“…6.2). Deze vorm van dynamisch kustbeheer wordt steeds meer onderzocht en toegepast op locaties waar sprake is van afslagkusten (Keijsers et al, 2015;Riksen et al, 2016), met als doel duinen te laten meebewegen met dynamische processen in de zeereep wat bijdraagt aan kustveiligheid, natuurkwaliteit, klimaatbestendigheid en goedkoper onderhoud (Milieufederatie Noord-Holland, 2013;Lammerts & Van Haperen, 2014). Deze indeling sluit nauw aan op de landschapsecologische gebiedsindeling in het conceptbeheerplan (Meijer et al, 2014).…”

Fresh groundwater resources in a large sand replenishment

“…Since 1990 the application of sand nourishments, particularly beach and shoreface nourishments, has become the dominant coastal defence strategy. Sand nourishments are applied on an annual basis -where necessary -to maintain the position of the coastline (Keijsers et al, 2015;de Ruig and Hillen, 1997). …”

Preface: climate change proof flood risk management

“…Consecutive papers focus on specific flood risk management-related subjects, namely on the reliability of risk assessments (De Moel et al 2015) which is a prerequisite for decision making, and on methods for riskbased standard setting for flood protection instead of using design floods plus some extra leeboard (Tsimopoulou et al 2015). The next two papers address the question how much flood protection can be achieved by deploying nature-based measures, respectively sand nourishments to the exposed sandy coast (Keijsers et al 2015) and promoting the development of saltmarshes in more sheltered coastal environments (Van Loon-Steensma, 2015). The following paper (Nillesen and Kok 2015) addresses the design of flood defences not only for the sake of flood protection, but also in view of their potential positive sideeffects for everyday use.…”