The "Eider-Kettentiden" project aims to develop a deeper understanding of the interaction between increased North Sea water levels and inland flooding events in the Eider-Treene system and, based on this, to identify critical drainage conditions in the Eider catchment area. Kettentiden or so called compound Tides represent a sequence of increased tidal low water levels that prevent or restrict drainage into the North Sea and therefore represent a particular challenge for drainage management. The use of statistical and hydraulic methods is intended to create a sound foundation for the derivation of design rules for flood scenarios and suitable adaptation measures.
The Eider catchment covers an area of approximately 2,702 km² and includes diverse landscapes such as marshes, geest regions and floodplains. The area is influenced by both inland flooding and storm surges from the North Sea, making the study of the interactions between these two phenomena particularly relevant.
A key component of the project is the analysis the operation of the Eider barrage. In the event of (expected) inland flood discharges and increased low tide levels in the North Sea, the barrage is operated in sluice mode at the request of the Schleswig-Holstein State Agency for Coastal Defence, National Park and Marine Protection. The embanked tidal Eider serves as a retention area. The sluice operation usually begins at low tide and can last for several tides, with the barrage being opened intermittently only for drainage purposes.
Univariate and multivariate statistical analyses are conducted out to determine the probabilities for the joint occurrence of compound tides of different durations and inland floods. For this purpose, copula functions are used to statistically model the dependencies between different hydrological variables. Copula functions can describe and statistically classify complex relationships and joint extreme events, such as the simultaneous occurrence of increased low tide levels and inland flooding events.
In addition, the effects of climate change on future flood scenarios and drainage conditions are analysed. The analysis of large-scale weather patterns and the evaluation of climate impact projections help to anticipate possible future changes in hydrological conditions and to develop appropriate adaptation strategies.
https://www.schleswig-holstein.de - Der Landesbetrieb für Küstenschutz, Nationalpark und Meeresschutz Schleswig-Holstein
May 2024 - April 2025