Silicate mountain stream rich in coarse material

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The Ilm near Langewiesen , river type 5

The coarse material-rich, siliceous low mountain range (type 5) is one of the flowing water types specified by the LAWA . With a length of over 18,000 km, it is the most common type of running water in Germany and in 2011 was selected by the Federal Ministry for the Environment as the type of water body of the year .


Depending on the shape of the valley, the streams run in stretched to weakly meandering river beds, which consist of a main channel and, in some cases, further secondary channels. The river bed consists in quiet sections of fine-grained, but otherwise almost exclusively of coarse substrate such as stones and gravel. Large gravel banks and ponds below deadwood or root barriers are common. Characteristic is a constant alternation between flat rapid and deeper stills. Large fluctuations in discharge occur over the course of the year.

Coarse material rich, silicate low mountain range streams occur in contrast to the coarse material rich carbonate low mountain range brooks in slate , granite , gneiss or volcanic areas.

Flora and fauna

There are many different types of invertebrates such as stone , mayfly and caddis fly larvae as well as water beetles , which are often very demanding in terms of current, oxygen content and temperature. Common fish species are, for example, brown trout , bullhead , loach or the brown lamprey . The dipper is common.

Due to the relatively strong erosion, aquatic plants play a subordinate role. Water mosses such as brook spade moss or bristle red algae can settle on larger, stable stones . Plankton does not exist.