Étude de l'évolution des littoraux dunaires de la Côte d'Opale à différentes échelles de temps : analyse de leur capacité de régénération post-tempête

Abstract : Coastal dunes are fundamental elements of sandy coastal systems dynamic. They may experience a variable response to coastal erosion, in relation to their ability to withstand storm effects and to recover from erosion. Global sea level rise, related to global warming, would considerably affect coastal systems and hence the sensitivity of coastal dunes to erosion. The main objective of this thesis is to study the evolution of the Côte d'Opale coastal dunes at different time scales in order to evoluate their capacity to resist and/or to recover from storm impacts. Over long term periods (nearly 68 years), shoreline evolution analysis from orthorectified aerial photographs revealed that more than half of the Côte d'Opale coastal dunes are stable or prograding and thus, are resilient. Their evolution over 5-year periods highlighted a strong spatial and temporal variability which is directly linked to weather and hydrodynamic conditions, especially the occurence of storms during heigh water levels. At medium and short term scales, topographic surveys from LiDAR and in-situ measurements, coupled with metrological and hydrodynamic data, showed a different morphological response between adjacent coastal dune areas. This is related to variations in morphological parameters such as dune foot elevation, width and volume of the upper-beach during the studied periods. Results show also that coastal dunes recovery from storms can be a very long process at our study areas, suggesting that foredunes in a state of mesoscale stability may experience more frequent erosion with currents sea level rise.
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Amar Zemmour. Étude de l'évolution des littoraux dunaires de la Côte d'Opale à différentes échelles de temps : analyse de leur capacité de régénération post-tempête. Sciences de la Terre. Université du Littoral Côte d'Opale, 2019. Français. ⟨NNT : 2019DUNK0525⟩. ⟨tel-02270709⟩

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