Event‐Scale Dynamics of a Parabolic Dune and Its Relevance for Mesoscale Evolution

Abstract

Parabolic dunes are widespread aeolian landforms found in a variety of environments. Despite modeling advances and good understanding of how they evolve, there is limited empirical data on their dynamics at short time scales of hours and on how these dynamics relate to their medium‐term evolution. This study presents the most comprehensive data set to date on aeolian processes (airflow and sediment transport) inside a parabolic dune at an event scale. This is coupled with information on elevation changes inside the landform to understand its morphological response to a single wind event. Results are contextualized against the medium‐term (years) allowing us to investigate one of the most persistent conundrums in geomorphology, that of the significance of short‐term findings for landform evolution. Our field data suggested three key findings: (1) sediment transport rates inside parabolic dunes correlate well with wind speeds rather than turbulence; (2) up to several tonnes of sand can move through these landforms in a few hours; and (3) short‐term elevation changes inside parabolic dunes can be complex and different from long‐term net spatial patterns, including simultaneous erosion and accumulation along the same wall. Modeled airflow patterns along the basin were similar to those measured in situ for a range of common wind directions, demonstrating the potential for strong transport during multiple events. Mesoscale analyses suggested that the measured event was representative of the type of events potentially driving significant geomorphic changes over years, with supply‐limiting conditions playing an important role in resultant flux amounts.

Morphodynamic interactions of continental shelf, beach and dunes: the Cabopino dune system in southern Mediterranean Spain

“…Transgressive dunes (Hesp and Walker, ) are usually associated with high energy dissipative and intermediate coasts and are normally only present on intermediate beaches where high energy storm waves help puncture the foredune zone and funnel sediment through large parabolic dunes (Hesp, 2012; Delgado‐Fernandez et al, ). They are rarely found next to reflective beaches or low energy systems.…”

Feedbacks between Biotic and Abiotic Processes Governing the Development of Foredune Blowouts: A Review

“…The conceptual model can be an important tool in predicting blowout development under different environmental and ecological conditions. A first step towards application could be revisiting existing field datasets (e.g., [9,13,14,22,122,123]) and evaluating measured interactions between blowout form and vegetation colonization within the lens of the new conceptual model. Subsequently we need to include these concepts into a predictive model framework able to represent the aforementioned stages and transitions.…”

“…Validation of our conceptual model should start by revisiting existing field observations (e.g., [9,13,14,22,122,123]). However, to investigate time-scales and occurrences of stage transitions across various foredune systems around the globe additional field observations on blowout dynamics become crucial.…”

Greedy parabolics: Wind flow direction within the deflation basin of parabolic dunes is governed by deflation basin width and depth

“…Therefore, the greater the proportion of the deflation basin the within ±15° of the landform's axis orientation, the greater likelihood the landform will continue to evolve in its antecedent orientation. (Smyth et al, 2012;Delgado-Fernandez et al, 2018).…”

“…White Sands, New Mexico) resulting in compound morphologies where dunes merge and override one another (Wolfe and David, 1997). Parabolic dunes occur in a range of environments including coastal dunes (Arens et al, 2004;Delgado-Fernandez et al, 2018;Hansen et al, 2009;Robertson-Rintoul, 1990), temperate grasslands (Wolfe and David, 1997) and semi-arid environments (Ardon et al, 2009) throughout the Americas, Europe, Australasia, North Africa, South Africa, the Middle East and North East Asia (Figure 2 in Yan and Baas, 2015).…”