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

Abstract. Coastal erosion and flooding are known to be linked, with erosion potentially exacerbating flood extents and risk, but analysis of the combined hazards is limited. This paper describes the CoasTER geographic database designed as a first step in integrating existing information on erosion and other relevant characteristics for Europe’s coastal floodplains to support flood assessment and climate services. The CoasTER database updates and builds on earlier erosion research and data sources. It also includes a coastal geomorphological typology which incorporates human modification in the form of hard engineering and infrastructure.

Almost 80 % (25,000 km) of shorelines associated with coastal floodplains are composed of erodible 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 over the last 40 years. The majority of floodplain shorelines are associated with either developed or agricultural areas and human structures are visible along almost 8,000 km of shoreline, restricting morphodynamic response to sea level rise. If the erosive trend continues for developed areas, over 2,500 km of shoreline will require further management to maintain current protection levels and nearly 1,000 km will require new management. The CoasTER database reveals the potential magnitude of erosion-flood interactions in the future defining where mobile sediments and coastal floodplains are co-located. It 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.