Accommodation space indicates dune development potential along an urbanized and frequently nourished coastline

Abstract

With densely populated areas well below mean sea level, the Netherlands relies heavily on its dunes to ensure coastal safety. About half of the sandy coastline, however, is subject to structural marine erosion and requires frequent sand nourishment as a counteractive measure. A key component of present-day coastal safety policy is creating favorable conditions for natural dune development. These conditions essentially involve (1) a steady supply of wind-blown sand towards (2) a wide accommodation space where sand can accumulate and dunes are sheltered from frequent storm surge impacts. This paper examines to what extent an experimental mega-scale beach nourishment (termed Zandmotor in Dutch) has contributed to creating accommodation space favorable for dune development. Using publicly available airborne lidar data and Sentinel-2 satellite imagery, favorable accommodation space is identified by comparing recent changes in coastal morphology against dune vegetation-cover dynamics. With a focus on European marram grass (Ammophila arenaria) as the most prominent dune-building species, this paper demonstrates that the Zandmotor supports an especially high potential for incipient (embryo) dunes to develop as most of its favorable accommodation space is located on the beach. However, considering the conditions required for successful marram grass establishment as well as persistent anthropogenic disturbances arising from recreation and nature management practices, it is not likely that dune development along this urbanized coastline reaches its full potential.