Raising dikes and managed realignment may be insufficient for maintaining current flood risk along the German Baltic Sea coast

Joshua Kiesel*, Lars E. Honsel, Marvin Lorenz, Ulf Gräwe, Athanasios T. Vafeidis

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Without upgrading existing adaptation, Germany is projected to be among those European countries that will suffer severe flood damages in 2100. Here we use a validated modeling framework to explore the effectiveness of two hypothetical upgrades to existing dike lines in reducing flood extent and population exposure along the German Baltic Sea coast. We perform a number of model runs where we increase the heights of existing dikes by 1.5 m, implement managed realignment as a nature-based solution, where physically plausible, and run a 200-year surge under two sea-level rise scenarios (1 and 1.5 m). We show that managed realignment is more effective in reducing future population exposure to coastal flooding compared to increasing dike heights. However, the maximum reduction in population exposure compared to a do-nothing approach amounts to only 26%, suggesting that even managed realignment is insufficient to maintain flood risk at today´s levels. The greatest potential for protecting people and property from future flooding lies in developing adaptation strategies for currently unprotected coastal sections.

Original languageEnglish
Article number433
JournalCommunications Earth and Environment
Volume4
Issue number1
DOIs
Publication statusPublished - Dec 2023

Bibliographical note

Funding Information:
JK, ML, ATV and UG were supported by the Federal Ministry of Education and Research (BMBF, funding code 03F0860H). This work is a contribution to the ECAS-Baltic project: Strategies of ecosystem-friendly coastal protection and ecosystem-supporting coastal adaptation for the German Baltic Sea Coast. JK would also like to thank Lars Michelsen for his support in the design and preparation of Figs. and . All authors would like to acknowledge Eric D. White and two anonymous referees for their thorough and constructive feedback, which greatly contributed to improving this manuscript. Finally, the authors would also like to thank the OpenStreetMap contributors and note that any OpenStreetMap (OSM) data used in our analyses is copyrighted by OpenStreetMap contributors and is available at https://www.openstreetmap.org .

Publisher Copyright:
© 2023, The Author(s).

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