Barrier islands serve as a moving coastal border for bays, estuaries, and mainland coastal areas. They protect these more vulnerable habitats from coastal winds, waves, and storm surges. These islands exhibit diverse dune morphologies, ranging from high to low dunes, with intermediate zones named transitional dunes, as seen in the eastern part of the Dutch Barrier Islands.

This study examines the intricate interplay between aeolian transport, vegetation, wave dynamics, and storm events in shaping these dune forms, investigating the morphological parameters that govern dune formation and susceptibility to storms, waves, and vegetation dynamics. A one-dimensional (cross-shore) numerical model was developed to simulate the sandy barrier island evolution spanning years to decades, as a function of the interplay between storminess, vegetation characteristics, and barrier morphology. The model was validated using historical data from the Wadden Sea. Unlike previous studies that typically examine these processes separately, this model combines these processes into a unified framework, facilitating a more holistic depiction of long-term barrier island evolution, revealing beach width as a key control on dune state.

The research highlights that wide beaches with abundant sediment supply promote the formation of high dunes, whereas narrow, sediment-limited beaches tend to form transitional or low dunes. These findings enhance the understanding of the interdependencies among coastal processes and offer predictive tools for coastal management under environmental conditions.