Restoration of a Tidal River Embankment

Large container ships approaching harbours via tidal rivers create strong currents and large ship waves. In the Elbe estuary near the Port of Hamburg with a tidal range of about 2,85 m the century old protection of the embankments show undulate shape even after frequent restoration. Analysis of the origin of the deformed embankment protections was done considering wind waves, ship waves and flow conditions from varying river discharges and tidal flows by using numerical and physical models which were calibrated with local field measurements. The river discharges vary between LQ = 145 m³/s and HQ = 3.620 m³/s at the gauge Neu Darchau. The analysis determines different reasons for the deformed protections. One reason is the construction of the embankment protection. Most embankments in the Hamburg harbour are protected with rubble or rip-rap protections. As the basement of the protection debris of destroyed buildings and quay structures are used. These are covered by loose granite stones. Another reason is the interaction of ship and wind induced waves, because even restored and redesigned embankment protections were deformed. The interaction processes were simulated with the numerical models SWAN and ODIFLOCS. The results were verified with physical models in a small towing tank of the FRANZIUS-Institute and field investigations.