Tidal flow

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A tidal river is a section of river that has changing water levels ( ebb and flow ) under the influence of the tide . In the confluence of the tidal rivers, the tidal range can be considerably larger than in the open sea due to the effects of damming. In the lowest section of the tidal rivers there is brackish water , upstream fresh water can also predominate.

For example, tidal rivers open to the North Sea are

• the Elbe
  • the sturgeon
  • the oste
• the Weser
  • the Hunte with Huntes Barrage
  • the Lesum with Lesum barriers
  • the Ochtum with the Ochtum barrage
• the Ems with barrage
• the Eider with Eider dam and Eidersperrwerk

Corresponding to the displacement of large amounts of water with the tidal range in the river, the direction of flow of the river is reversed in the vicinity of the mouth - rather only for less than half of the 12h25 tidal period, because with the constant inflow superimposed and decaying upstream, even if resonance phenomena can occur in some areas .

Tidal flows are generally endangered by storm surges . Flood protection measures such as dykes and barrages are therefore often required.

Biologically, tidal flows differ from other rivers in particular through the brackish water zone and freshwater mud flats . See also the estuary .

See also

• Brackish water