Update of the Schleswig-Holstein State master plan for coastal flood defense and coastal protection with a focus on climate change adaptation

In 1963, under the impression of a catastrophic storm surge that hit the North Sea coast of Germany in 1962, Schleswig-Holsteins State Government released its first master plan for coastal flood defense and coastal protection. Subsequent State Governments updated the original plan from 1963 in the years 1977, 1986, 2001 and 2012 in order to consider socio-economic and natural developments as well as technical and scientific progress. This paper presents the fifth update of 2022, which focusses on climate change adaptation.

Without coastal flood defenses, about one quarter of Schleswig-Holstein with 333,000 inhabitants and 60 billion EUROS of real assets could flood during severe storm surges. Further, the 1,110 km long coastline almost completely consists of non-cohesive easily erodible sediments. These figures substantiate the socio-economic significance of coastal flood and erosion management and the need for sustainable climate change adaptation in Schleswig-Holstein. The adaptation strategy contained in the master plan consists of three components: technical measures, regional planning and the use of ecosystem services. In order to consider future sea level rise, the dimensioning of all technical flood defense measures includes a safety allowance of 0.5 m. The strengthening of state dikes, being the cornerstones of coastal flood defense in Schleswig-Holstein, further includes a flattening of the outer dike slope in order to reduce storm wave run up and to create building reserves for further adaptation as necessary. Safety allowance, flat outer dike slopes and building reserves can together compensate for a sea level rise of up to two meters. In regional plans, priority areas for coastal flood defense, coastal protection and climate change adaptation secure the availability of space needed for technical reinforcements as well as utility-free buffer zones landward of cliffs, dunes and beach ridges to allow for coastal retreat. Finally, the application of ecosystem-based measures, for example salt marsh enhancement techniques, acknowledges and uses the high natural resilience or adaptability of coastal ecosystems to sea level rise.