Marsh waters
The marshland (type 22) is one of the types of flowing water specified by LAWA . In Germany it occurs only in the area of the marshland on the northwest German coast. Due to the possible strong differences in the animal and plant communities within this water type, which are difficult to detect due to human influences, a distinction is currently made between the subtypes of currents of marshes , rivers of marshes and waters of marshes (catchment area only within marshes).
Water structure
Marsh waters are widely curved with a trough-shaped cross profile. The banks are flat and partly designed as tidal flats, but there are also low impact slopes . The current of the waters is low and periodically reverses to the rhythm of ebb and flow . The bottom is relatively uniform and mostly consists of clay, silt and, in places, peat.
Today, due to the dikes, there are hardly any near-natural marsh waters.
Subdivision
The LAWA distinguishes between four subtypes of marsh waters:
- 22.1 “Waters of the marshes”: Waters whose water balance is regulated by sluices (protection against high tide water ) and pumping stations .
- 22.2 “Rivers of the Marshes”: Medium-sized bodies of water
- (without number) with a clear tidal range of up to 2.5 m.
- (without number) with tidal range over 2.5 m.
- 22.3 “Streams of the Marshes”: The tidal areas of the Elbe and Weser
Flora and fauna
The living things have to cope with the salinity and the influence of the tides. Depending on the strength of these factors, different invertebrates such as few bristles , certain amphipods and mosquitoes can be found. The fish fauna also differs greatly depending on the salt content; freshwater species such as perch or mud whip , brackish water species such as the flounder and sometimes some marine species can be found.
Most of the reeds grow on the banks of the marshland , sometimes there is also a wooded border.
Examples
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- Profile of the river type 22 on wasserblick.net (PDF; 125 kB) accessed on November 24, 2011