A geospatial database of coastal characteristics for erosion assessment of Europe's coastal floodplains

Coastal erosion and flooding are linked, with erosion potentially exacerbating flood extents and risk, but analysis of the combined hazards is limited. This paper describes the CoasTER geographic database specifically designed for the first time to integrate existing information on erosion and other relevant characteristics for Europe's coastal floodplains. The CoasTER database updates and builds on earlier erosion research and data sources. At the European scale, it combines fundamental erosion-relevant information (sediment type, land use, floodplains, geomorphology, historical shoreline movement trend) on a standard shoreline to highlight the potential magnitude of erosion-flood interactions by defining where mobile sediments and coastal floodplains are co-located. It also identifies where morphodynamic response to sea-level rise is constrained due to structures/infrastructure.

Results indicate almost 80 % (25 000 km) of the total shoreline length associated with European coastal floodplains (approx. 31 000 km) are composed of mobile sediments, with coastal wetlands being the most prevalent geomorphological type. While accretion is the dominant historical trend for these shorelines, approximately 27 % are currently classed as eroding at over 0.5 m yr−1 over the last 40 years. The majority of floodplain shorelines are associated with either developed or agricultural areas and constraining human structures that occur along almost 8000 km of shoreline. The CoasTER database demonstrates that episodic and/or long-term erosion and coastal flooding is a Europe-wide issue that deserves the attention of local to European decision-makers in order to define a coherent management strategy.