New trends in coastal erosion monitoring at the European scale: The Space for Shore comprehensive solution
Résumé
The coastal erosion is defined as the loss or displacement of land along the coastline due to the action of rain, ice and atmospheric and marine forcing. In Europe, about 25% of the European coastline for which data is available is currently retreating and erosion up to 20-30 m when severe storm occurs are frequent. In the context of climate change and sea level rise, the coastal erosion issue will be even more relevant in the future, as both the frequency and strength of storm events are likely to increase causing billions of Euros of damages.
Dealing with coastal erosion implies to provide highly precise (sub-metric) geo-located information about shorelines on a yearly to decadal timescale. For this reason, the classical approach for coastal erosion assessment has been based on the analysis of historical aerial orthophotos (enabling the extraction of longterm trends), along with GPS field observations (short-term beach and shoreline changes at the timescale of storm events).
These past 20 years, the use of new technologies for coastal change and shoreline monitoring has significantly increased (airborne lidar topographic surveys, photogrammetry, in situ laser scanning) but their definitive adoption still depends on their cost to effectiveness ratio. In the meanwhile, satellite remote sensing has shown to be adequate and relatively cost-effective for the extraction and monitoring of shoreline change over sandy coasts, and other relevant indicators of coastal erosion (beach and cliff morphological patterns, nearshore bathymetry, tidal flat change in semi-enclosed bays,…).
In the framework of the ESA Coastal Erosion Project, the future “Space for Shore” service intends to unravel the remaining technical issues and to provide a large European end user community spread over 5 countries with prototyped products, that are based on the Copernicus Sentinel-1 and Sentinel-2 missions and, to a certain extent, on Third Party Missions. The challenge definitely resides in the adequation between EO-data ground resolution, satellite product accuracy and the rate of coastal erosion and shoreline change, collectively targeting the retrieval of major coastal indicators designed to support decision-making.
This communication proposes an overview of the first results obtained from the Proof-of-Concept activities run this year, accordingly to the set of products required by European coastal managers in charge of shoreline management.
A soundful validation of these prototyped products is also performed assessing satellite real capability to meet end user requirements in terms mainly of measurement accuracy and temporal revisit. Finally, in conclusion, benefits for the coastal community are addressed along with some perspectives for wide service deployment over Europe.