Spatio-Temporal Variability in Accretion and Erosion of Coastal Foredunes in the Netherlands: Regional Climate and Local Topography

Abstract

Depending on the amount of aeolian sediment input and dune erosion, dune size and morphology change over time. Since coastal foredunes play an important role in the Dutch coastal defence, it is important to have good insight in the main factors that control these changes. In this paper the temporal variations in foredune erosion and accretion were studied in relation to proxies for aeolian transport potential and storminess using yearly elevation measurements from 1965 to 2012 for six sections of the Dutch coast. Longshore differences in the relative impacts of erosion and accretion were examined in relation to local beach width. The results show that temporal variability in foredune accretion and erosion is highest in narrow beach sections. Here, dune erosion alternates with accretion, with variability displaying strong correlations with yearly values of storminess (maximum sea levels). In wider beach sections, dune erosion is less frequent, with lower temporal variability and stronger correlations with time series of transport potential. In erosion dominated years, eroded volumes decrease from narrow to wider beaches. When accretion dominates, dune-volume changes are relatively constant alongshore. Dune erosion is therefore suggested to control spatial variability in dune-volume changes. On a scale of decades, the volume of foredunes tends to increase more on wider beaches. However, where widths exceed 200 to 300 m, this trend is no longer observed.

Exploring the contributions of vegetation and dune size to early dune development using unmanned aerial vehicle (UAV) imaging

“…The net growth of our foredune was approximately 30 m 3 m −1 foredune parallel to the sea for a period of 10 months. This growth rate does also occur at other places along the Dutch coast, but is not very common (Keijsers et al, 2014). Storm intensity is also influenced by beach morphology.…”

“…Most research on coastal dune growth and erosion have focused on processes and factors that influence the supply of sand to the dunes and the effect of storm intensity on dune erosion (Anthony, 2013;Haerens et al, 2012;Houser et al, 2008;Keijsers et al, 2014;Saye et al, 2005;de Vries et al, 2012). However, how coastal nebkha dune growth and erosion rates are influenced by the individual dune characteristics, such as dune size, vegetation and degree of sheltering, are less well studied.…”

“…Whether the latter also applies to nebkha dunes, is unknown. Differences in vegetation density between plant species are known to modify sand deposition (Arens, 1996;Hesp, 1983;Keijsers et al, 2014;Zarnetske et al, 2012), storm erosion (Charbonneau et al, 2017;Seabloom et al, 2013), and dune morphology (Du et al, 2010;Hacker et al, 2012;Hesp, 1988). Sheltering by other nebkha dunes can decrease the sand supply but can also reduce erosion by waves (Arens, 1996;Lima et al, 2015;Luo et al, 2014;Montreuil et al, 2013).…”

Environmental Impacts—Coastal Ecosystems

“…Dunes and beaches are linked in a dynamic and complex sediment exchange system, where losses of sediment from foredunes during storms alternate with inter-storm deposition gains (e.g. Keijsers et al 2014), potentially leaving the overall shoreline position unchanged in the long term. More frequent storm erosion of the foredune toe may therefore not necessarily result in permanent loss of sediment from the coastal system.…”

The Usumacinta–Grijalva beach-ridge plain in southern Mexico: a high-resolution archive of river discharge and precipitation

“…Rates are much higher than the average long-term aeolian accretion rates of 0.1-0.6 m 3 m −1 yr −1 for three beach-ridge plains in south-eastern Australia (Oliver, 2016) but are relative low compared to average long-term accretion rates for larger-scale foredunes, which roughly vary between 5 and 20 m 3 m −1 yr −1 (e.g. Aagaard et al, 2004;Ollerhead et al, 2013;Keijsers et al, 2014).…”