Periodic Reporting for period 1 - ERoDES (Examination of the recent past and future Response of coastal Dunes to Extreme storms and Sea level rise)
Période du rapport: 2021-09-01 au 2024-08-31
Climate change is expected to cause more intense extreme weather events and an increase in extreme sea levels along the coastline of Europe and other continents.
It is thus crucial to understand coastal dunes behaviour, since they serve as the first line of protection against coastal erosion and flooding for coastal communities.
The ERoDES project helped to gain a better understanding of coastal dune dynamics and provided useful information and tools for short-and long-term coastal management strategies along the Atlantic coast of Europe, especially along the south west coast of France where dunes are the most dynamic ones.
First, the magnitude of storm-driven sand volume loss was shown to be mainly controlled by dune face slope during extreme storms. Dunes with steeper pre-storm slopes lost the largest volumes of sand. Dune recovery following the extreme storms was shown to be site specific, with dunes that either progressively returned to their pre-storm morphology or were reshaped while recovering. Percentage of dune sand volume recovery was well correlated to the local and long-term satellite-derived shoreline change rate computed from 1984 to 2021 suggesting that dune recovery is mainly controlled by the local coastal sediment budget.
Second, although no significant changes occured after the 2014 extreme storms along some of the Atlantic coastal dunes, windy events over 6 years caused aeolian sediment transport driving landwards dune migration up to 50 meters along the south west coast of France. The temporal and spatial variability of vegetation was shown to be a key factor in controlling this migration. An emerging aeolian transport model, AeoLiS, was shown to be a relevant tool to model such migration and was coupled to well established marine processes models (XBeach, ShoreFor).
Third, satellite imagery such as high resolution images (Sentinel-2) or very high resolution (Pleaides) was shown to be a valuable source of data to monitor spatial and temporal variability of vegetation cover along coastal dunes. Furthermore, it was shown that tri-stereo Pleaides images can also be used to recreate dune topography. This has worldwide implications for the monitoring of coastal dunes.
It is thus crucial to understand coastal dunes behaviour, since they serve as the first line of protection against coastal erosion and flooding for coastal communities.
The ERoDES project helped to gain a better understanding of coastal dune dynamics and provided useful information and tools for short-and long-term coastal management strategies along the Atlantic coast of Europe, especially along the south west coast of France where dunes are the most dynamic ones.
First, the magnitude of storm-driven sand volume loss was shown to be mainly controlled by dune face slope during extreme storms. Dunes with steeper pre-storm slopes lost the largest volumes of sand. Dune recovery following the extreme storms was shown to be site specific, with dunes that either progressively returned to their pre-storm morphology or were reshaped while recovering. Percentage of dune sand volume recovery was well correlated to the local and long-term satellite-derived shoreline change rate computed from 1984 to 2021 suggesting that dune recovery is mainly controlled by the local coastal sediment budget.
Second, although no significant changes occured after the 2014 extreme storms along some of the Atlantic coastal dunes, windy events over 6 years caused aeolian sediment transport driving landwards dune migration up to 50 meters along the south west coast of France. The temporal and spatial variability of vegetation was shown to be a key factor in controlling this migration. An emerging aeolian transport model, AeoLiS, was shown to be a relevant tool to model such migration and was coupled to well established marine processes models (XBeach, ShoreFor).
Third, satellite imagery such as high resolution images (Sentinel-2) or very high resolution (Pleaides) was shown to be a valuable source of data to monitor spatial and temporal variability of vegetation cover along coastal dunes. Furthermore, it was shown that tri-stereo Pleaides images can also be used to recreate dune topography. This has worldwide implications for the monitoring of coastal dunes.
Airborne LiDAR datasets acquired through different european coastal monitoring programmes were processed and allowed to monitor coastal dune changes along the Atlantic coast of Europe
The AeoLiS model, that models aeolian sediment transport was calibrated and validated along dynamic dunes along the south west coast of France and was coupled to other numerical models, such as XBeach and Shorefor, that incorporate marine processes
High and very high resolution satellite images (Sentinel-2, Pléiades) were shown to be innovative source of topographic and vegetation cover data along coastal dunes
The AeoLiS model, that models aeolian sediment transport was calibrated and validated along dynamic dunes along the south west coast of France and was coupled to other numerical models, such as XBeach and Shorefor, that incorporate marine processes
High and very high resolution satellite images (Sentinel-2, Pléiades) were shown to be innovative source of topographic and vegetation cover data along coastal dunes
Monitoring, understanding and modelling landward dune migration has a strong socio-economic impact for coastal communities living behind. Furthermore, in the south west of France, coastal managers closely monitor dune migration which invades pine forests that are exploited in the region