Background
In late 2013, a sudden and significant increase in suspended sediment concentrations was observed in the Elbe estuary. In the following years, this led to a substantial rise in maintenance dredging volumes, particularly within the Port of Hamburg. Current research suggests that this increase is largely due to the remobilization of vast quantities of fine sediments from tidal flats and salt marshes, triggered by extreme events such as the storm surge "Xaver." Despite the high relevance of these processes, there is a lack of detailed understanding regarding the exchange mechanisms between the estuary and the tidal flats, as well as the specific hydrodynamic conditions under which these areas act as sediment sources or sinks.
Objectives
The primary goal of SEDYWA is to deepen the understanding of sediment exchange processes in estuarine mouth areas. The project focuses on the deposition and erosion behavior of cohesive fine sediments. Specifically, it aims to answer the following questions:
- Under which hydrodynamic loads (currents, waves) does erosion or deposition occur?
- Which grain size fractions are affected depending on the specific load?
- How can these processes be mathematically described to improve the predictive capabilities of numerical models?
- What impact will rising sea levels due to climate change have on these dynamics?
Methodology
To address these research questions, the project employs an integrated approach combining field measurements, laboratory experiments, and numerical simulations:
- Field Measurements: Use of stationary measuring stations on the tidal flats (including ADV, ADCP, turbidity sensors, and floc cameras) for high-resolution recording of flow velocities, bed shear stress, and sediment concentrations.
- Drone Surveys & Sampling: Regular, area-wide mapping of tidal flat topography using drones, alongside grid-based sediment sampling to analyze spatial heterogeneity.
- Laboratory Studies: Determination of erodibility (critical shear stresses) and deposition behavior of natural samples using specialized experimental setups (e.g., the C-GEMS closed microcosm system).
- Modeling: Implementation of the newly gained insights and mathematical formulations into the numerical Elbe model maintained by the Federal Waterways Engineering and Research Institute (BAW).
Impact and Partners
The results will serve as a foundation for sustainable sediment management in estuaries. The project is led by the Hamburg University of Technology (TUHH). Key associated partners include the Federal Waterways Engineering and Research Institute (BAW), the Hamburg Port Authority (HPA), and the Federal Waterways and Shipping Administration (WSA Elbe-Nordsee).
Project Data:
- Duration: March 1, 2026 – February 28, 2029 (3 years)
- Funding: KFKI (German Coastal Engineering Research Council)
- Project Lead: Prof. Dr.-Ing. Peter Fröhle
