Primary drivers of dune cover and shoreline dynamics: A conceptual model based on the Iberian Atlantic coast

Coastal dunes evolve in direct response to primary drivers, such as wind and waves, which can significantly influence the landscape. Here, we examine the effects of the wind and wave regimes on the vegetation cover and shoreline position of the dune system that makes up the Donin tilde os barrier on the rocky NW Iberian coast since the middle of the 20th century. By studying a series of aerial images, we determined that the vegetated dunes experienced net seaward shoreline advance at an average rate of 1.28 +/- 0.01 m/year and an overall dune vegetation coverage expansion of 50.5 %. Available local atmospheric data indicated that wind stilling was the main factor responsible for these trends. However, the shoreline evolution process included annual-to-decadal periods dominated by stalled or reversed advances in energetic winters when waves could reach the foredune, causing erosion and vegetation cover deterioration. Consecutive energetic winters resulted in severe foredune erosion and slow to no recovery of shoreline advance thereafter. This work presents a case study in which a new conceptual model of the opposite and unbalanced effects of wind stilling and storm surges on foredune evolution dynamics is discussed and established under the current climate change scenario.

Automated summary

In this study, the effects of wind and wave regimes on the vegetation cover and shoreline position of the Donin tilde os barrier on the NW Iberian coast were examined. It was found that wind stilling was the main factor responsible for the expansion of dune vegetation coverage and seaward shoreline advance. However, energetic winters with strong winds and waves caused erosion and deterioration of vegetation cover, resulting in reversed or stalled advances in shoreline evolution.