Modelling the Retreat of a Coastal Dune under Changing Winds.

ABSTRACT Gabarrou, S.; Le Cozannet, G.; Parteli, E.J.R.; Pedreros, R.; Guerber, E.; Millescamps, B.; Mallet, C., and Oliveros, C., 2018. Modelling the Retreat of a Coastal Dune under Changing Winds. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 166–170. Coconut Creek (Florida), ISSN 0749-0208. Coastal dunes can move in response to winds and cause serious hazard to human assets. Changes in wind patterns, potentially occurring as a consequence of climate change or variability, could affect rates of aeolian transport and migration velocity of coastal dunes. However, most of previous modeling studies were conducted assuming that aeolian bedforms are subject to constant wind velocities. This article presents a modeling of the mobility of the Dune du Pilat in Aquitaine, a coastal transverse dune exposed to winds of varying intensity. It applies well-established models and empirical formula for aeolian dune migration, including a model previously validated against measurements of real profiles of desert and coastal dunes. The average migration velocity of Pilat dune predicted by the models is about 3m/year, which is in good agreement with in-situ measurements. To test the response of transverse dune mobility to changing winds, virtual wind time series are generated using a stochastic model. Modelling experiments suggest that more frequent storms have less impacts than more intense winds. Due to the size of the Pilat Dune (altitude of about 100m), these result in moderate changes in the average dune velocity. This study shows that the approach of combining a stochastic model for winds with a morphodynamic dune model can provide valuable insight into how aeolian bedforms respond to changes in flow conditions potentially caused by climate change. [ABSTRACT FROM AUTHOR]