Foredune notch longevity and spatial evolution across northwest Europe

Foredune notches are increasingly used as a coastal dune management interventions to promote aeolian sediment transport, increase bare sand, and support early successional habitats. Yet understanding of their long-term morphological evolution, persistence, and the extent to which design and wind regime influence outcomes remains limited. This article presents the first systematic, multi-site, multi-year assessment of notch morphological evolution. Aerial imagery spanning periods of 5–12 years was used to quantify changes in area, cross-shore length, longshore width, and slot width for 58 notches. Long-term trends in these parameters were assessed using Theil–Sen regression. Regression models were then used to test the influence of initial constructed morphology, wind regime, and orientation on the observed rates of notch change. Results show that notch evolution is predominantly characterised by contraction. Median notch persistence estimates ranged from approximately 11 to 21 years, but with wide variability between metrics, sites, and regions. Clear regional contrasts were found, with notches in the United Kingdom showing more statistically significant morphological trends and faster rates of contraction than those in the Netherlands, where responses were weaker and more variable. Initial constructed morphology and wind regime explained only modest proportions of variance in evolution rates, indicating the influence of additional site-specific controls that are not captured in the models. Overall, this study shows that notches can remain geomorphologically active over decadal timescales, but their evolution and persistence are highly context dependent. The results highlight the need to consider design and site setting when designing and evaluating notches as long-term dune management interventions.