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Conference Papers Year : 2013

Modeling aeolian coastal dunes mobility in Aquitaine, South Western France

Abstract

The aquitaine coast (South western France) comprises a 230 km coastline of sandy beaches and dunes. Since 1979, most of the coastal dunes of Aquitaine are softly managed by maintaining their vegetation. When wind erosion landforms appear, they are stabilized by bringing vegetation debris and wind obstacles. One question is to understand if dunes management could become softer without strong consequences for assets located behind the dunes. In absence of vegetation, such as in the Pyla dune, ongoing dune mobility is expected to affect a road and a tourism facility in the future. Finally, changing wind patterns potentially due to climate change or variability may affect Aeolian sand transport. These questions motivated a modelling study of coastal dunes mobility based on examples in Aquitaine. In this study we used an aeolian dunes model previously validated in deserts, in order to evaluate its potential for representing dunes movements. The results show poor capabilities to represent the competition between vegetation growth and winds in the case of vegetated dunes. In the case of Dune du Pyla, while the profile of the dune is not modelled satisfactorily, the modelled dune velocity (3m/year) are in good agreements with an analysis of maps (between 2 and 4 m/year from 1964 to 1994). We used a statistical model that generates longer wind time series in order to estimate uncertainties and longer term dunes mobility due to changing wind patterns. Model uncertainties are lower than the variability due to observations, highlighting the fact that strong winds transport is underestimated in the model. According to the model, an intensification of winds by 15% would lead to increase dune velocity of 9%. More frequent storms would lead to averaged mobility rates of up to 4m/year. Although these modelling results must be considered carefully, the approach of combining a stochastic model for winds with a physical dune model provides some insight to their future evolution.

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Earth Sciences
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Dates and versions

hal-00802746 , version 1 (20-03-2013)

Identifiers

  • HAL Id : hal-00802746 , version 1

Cite

Sylvain Gabarrou, Gonéri Le Cozannet, Eric Parteli, Rodrigo Pedreros, Carlos Oliveros, et al.. Modeling aeolian coastal dunes mobility in Aquitaine, South Western France. 8th IAG - International Conference on Geomorphology 2013, Aug 2013, Le Villette, France. ⟨hal-00802746⟩

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