Textbook dune: Is there a representative and scale‐invariant beach‐dune profile?

Abstract

The Coastal Dune Model, used to examine controls on dune development and evolution, includes negative feedback between the wind and the evolving topography that results in a scale‐invariant beach‐dune profile. While a limited number of reference profiles appear to support the Coastal Dune Model assumption of scale‐invariance, previously published studies and conceptual models suggest that the beach‐dune profile is not scale‐invariant. Using a combination of journal articles, textbooks, and remotely sensed data from Prince Edward Island, Washington state, and Texas, this short communication finds that there is no evidence for a scale‐invariant beach‐dune profile within and between field sites. Variability in the beach‐dune profile is due to site‐specific and scale‐dependent controls on the beach and the dune that are often highlighted in the conceptual models that authors use to depict the controls on sediment supply and transport from the beach to the dune. Results highlight a need to critically evaluate the assumptions and applications of models such as the Coastal Dune Model, and to explore how and when sites can be considered representative and in support of model results.

Exploring Controls on Coastal Dune Growth Through a Simplified Model

“…These considerations are in line with the remarks of Houser et al. (2022) that the repetition and recurrence of surf and aeolian processes lead to the observation of similar beach‐dune profiles, while individual foredune topographies can deviate from what may appear as an equilibrium profile due to site‐specific and scale‐dependent controls and history.…”

“…Schwarz et al (2021) also postulated that the sediment flux at the dune crest is ultimately limited by the wind velocity and the distance traveled over vegetation. These considerations are in line with the remarks of Houser et al (2022) that the repetition and recurrence of surf and aeolian processes lead to the observation of similar beach-dune profiles, while individual foredune topographies can deviate from what may appear as an equilibrium profile due to site-specific and scale-dependent controls and history.…”

“…Their importance as ecosystem service providers has been widely acknowledged, motivating research on the different aspects controlling the evolution of these systems, such as vegetation cover (e.g., Talavera et al., 2022), dune shape, beach state (e.g., Garzon et al., 2022) and the processes controlling dynamics over distinct temporal scales, from event‐scale (e.g., Costas et al., 2020) to multi‐decadal (e.g., Herrero et al., 2020) changes. Coastal dunes display not only significant morphological variability alongshore (Houser, 2013; Houser et al., 2018; Moore et al., 2018), but also variable response depending on the shoreline trends at the adjacent beach (Brodie et al., 2019; Houser et al., 2022). Dune shape (i.e., aspect ratio or ratio between the height and width) has been suggested to influence storm‐induced dune erosion (Itzkin et al., 2020), while dune height has been traditionally used to assess the impact of storms at sandy coasts (Ferreira et al., 2016; Sallenger, 2000).…”