Assessment of Vulnerability and Adaptation to Sea-Level Rise for the Coastal Zone of Germany

Abstract Germany's coast extends over 3700 km on both the North and Baltic Seas and is shared by five coastal states. Major seaport cities, Hamburg and Bremen, form two of these states, whereas rural areas and small and medium-size coastal towns comprise the other three coastal states. Along the coast large low-lying areas are already threatened by recurring storm flood events and erosion. Accelerated sea-level rise therefore exacerbates a high-risk situation. It is estimated that under a 1-m accelerated sea-level rise scenario the recurrence of devastating storm floods that presently have a probability of 1 in 100 will decrease to a 1 in 10 or even 1 in 1 probability. Vulnerability assessments have been carried out in Germany at three scales: (i) the national level, i.e., for all coastal areas lying below 5 m (Baltic Sea Coast) and 10 m (North Sea Coast), (ii) the regional level for the coastal state of Schleswig-Holstein, and (iii) the local level for selected communities within this state. When comparing findings from these analyses, the results show that the economic risks of flooding and erosion are highest when detailed studies covering the full range of infrastructure assets are used. However, the actual risk areas in detailed studies may be more confined when considering local topography and infrastructure such as road dams. Nationally, an accelerated sea-level rise of 1 m would put more than 300,000 people at risk in the coastal cities and communities, and economic values endangered by flooding and erosion would amount to more than 300 billion US$ (based on 1995 values). This is why German coastal states are following a strategy based on hard coastal protection measures against flooding, although authorities realize that maintaining and/or improving these defence structures might become rather costly in the long-term. Although additional investment in flood and erosion protection will be considerable (estimated at more than 500 million US$) this seems manageable for the national and regional economies. On the other hand, hard coastline defence and accelerated sea-level rise will increase “coastal squeeze” on the seaward side, endangering important coastal ecosystems such as tidal flats (Wadden Sea), saltmarshes, and dunes. Currently there is no strategy to remedy this increasing ecological vulnerability.