| dc.description.abstract | Coastal management practices intended to strengthen established foredunes have contributed
to the stabilization of coastal ecosystems. As a result, the biodiversity within these ecosystems, as well as their ability to grow with rising sea levels, declined. To counteract these adverse trends, some coastal management projects nowadays aim to restore dynamics in coastal ecosystems
through the excavation of foredune notches, gaps in the most seaward dune that resemble naturally occuring trough blowouts. It is essential to understand how these restoration measures
effect the spatio-temporal evolution of the coastal ecosystem. However, knowledge regarding the
physical-ecological interactions that influence the evolution of restored coastal ecosystems,
especially after initial developments, is limited. Using annual lidar data and freely available
Landsat and Sentinel-2 satellite imagery, this study examines the development of a coastal
dunefield at Terschelling, the Netherlands, where sand trapping fences were removed and
notches were excavated through a 5-km long unvegetated foredune in 1995. The results reveal
that the restoration measures initially led to remarkable dynamism, with sand surface areas
gaining ~2.85 ha/yr on average and absolute sand volume change rates reaching up to ~7.1×105
m3/yr. The unvegetated rolling foredune eroded and new foredunes and transgressive sand sheets were gradually formed. As sand deposition on and seaward of the new foredunes limited sand transport towards the hinterland, aeolian erosion formed deflation basins between the new
foredunes and transgressive sand sheets. Vegetation primarily re-established in the deflation
basins, at elevations below 3 m mean sea level, near the water table, where depositional and
erosional rates were below 0.3 and 0.1 m/yr, respectively. Once established, vegetation spread
to higher elevations. The results indicate that vegetation growth within the dunefield is mainly
regulated by the geomorphological evolution, dynamism and topography of the dunefield.
Furthermore, the findings indicate that the dunefield will restabilize completely. Proactive
measures such as repeated excavation may be required to reintroduce dynamism. | |
