Isar mouth

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The Isar about 2 km before it flows into the Danube

The Isar is a tributary of the Danube . The mouth of the Isar is largely in the area of ​​the municipality of Moos , south of the city center of Deggendorf and east of Plattling . At 18 km of the Isar there is a diverse meadow landscape in which nature is largely left to its own devices. In order to make them accessible to visitors, the Infohaus Isarmündung was set up with its outdoor facilities and hiking trails. The last 1.63 kilometers of the Isar up to its confluence with the Danube lie entirely in the municipal area of ​​the city of Deggendorf (Fischerdorf district).

360 ° panorama of the mouth of the Isar - taken 100 meters above the Danube
Show as a spherical panorama

Flora and fauna

In the Isar estuary there are examples of the different habitats of a floodplain landscape :

Flowing waters

Studies in 1990/91 found 35 different fish species. The main fish here is the barbel , this section of the Isar is called a barbel region . The fish use gravel banks and gravelly, flatter bank areas as spawning grounds, and the structured banks as protection and feeding grounds. The species Schneider , Frauennerfling and the three perch species Schrätzer , Streber and Zingel live here, which are threatened with extinction in the entire Danube region .

Backwaters

Due to the relocation of the river bed of the Isar, which can flow freely within the last 10.5 km of the dykes , backwaters are formed in which various animal species that have adapted to still or standing water live. In the Isar estuary, 10 different amphibian species have been identified, such as B. the moor frog or the agile frog . The resulting pools and half-cut sections of the river also provide habitat for a variety of insects such as the great dragonfly . From this food supply z. B. the reed warbler . The very rare kingfisher , which mainly feeds on small fish , finds space for its breeding caves in the steep banks of the floodplain waters. Common fish that prefer still water are the rudd and roach .

Softwood alluvial forest

Wintry shore landscape in the Isar estuary

The characteristic of the softwood alluvial forest - in contrast to the hardwood alluvial forest - is the regular flooding by floods . The soft woods such as willow and poplar growing here are used by the very common beaver . The white-starred bluethroat has one of the most important occurrences in Central Europe.

Hardwood forest

The hardwood alluvial forest , which is on the other side of the dykes and is less flooded, is dominated by ash , common oak and sycamore maple . The very rare middle woodpecker finds food here and, in old wood, space for its nesting holes . The collar snapper is also a tree cavity breeder . Little light penetrates the ground through the dense tree tops and the bushes , which allows shade-loving plants to thrive. Liana-like plants such as clematis , hops and wild wine grow up on trees. Great rarities such as lady's slipper and beaker can be found here.

Wet and wet meadows

These areas, which were mainly used as litter meadows in the 17th and 18th centuries , offer living space for the curlew and whinchat , which builds their nests in dense vegetation on the ground. Amphibians serve these meadows as partial habitats, especially when suitable spawning waters are adjacent.

Burning, dry and poor grassland

As a mountain river with a steep gradient, the Isar brings a high load of bed load (mainly gravel ) from the Alps to the estuary. On former gravel and sandbanks that are now on land, plants that are particularly adapted to drought grow, which would be displaced by faster growing species under the competitive pressure of a normal, heavily fertilized and therefore very nutrient-rich meadow. Insects, such as the wart- bite, which is still common here, and the silver-green bluish , dominate these so-called stings . Particularly noteworthy is the Sammerner Heide , a remnant that has remained from the park-like landscape that was typical up until the 19th century around Moos: dry grass with individual trees standing on it determine the picture here. It was created when the farmers drove their cattle there and let them graze, which prevented the bush from becoming overgrown.

meaning

The Isar estuary as the only intact estuary of an Alpine river into the Danube enjoys special protection status as:

Endangerment and expansion of the Danube

The Isar flows into the Danube at Moos between Straubing and Vilshofen . This approximately 70 km long area is one of the last free-flowing and not yet built-up sections of the Danube in Europe. There are plans for this area to expand the Danube, which has been designated a federal waterway, for shipping. Here there are two expansion variants, the so-called variant A and variant C 2.80. Variant A, requested by the Bundestag resolution from 2002, is limited to river engineering measures and maintains the flow necessary for ecological balance. Variant C 2.80 provides the cutting of the Donauschlinge Mühlhamer loop at Aicha with a barrage (shoring) and a puncture channel in front. This variant was required by the state of Bavaria . If variant C 2.80 were implemented, the water would backflow into the Isar estuary. Large areas would be flooded as a result. Due to the political stalemate between the federal government and the state, there was no amicable agreement for an expansion variant. On February 27, 2013, however, the state government passed a cabinet resolution for a gentle expansion of the Danube between Straubing and Vilshofen, with the postponement of a section of the river.

See also

Web links

Commons : Isar estuary  - collection of images, videos and audio files

Individual evidence

  1. ↑ https://stadtgeschichte-muenchen.de/strassen/d_strasse.php?strasse=Plattlinger%20Stra%C3%9Fe
  2. ↑ "Project: Federal Project" Estuary of the Isar "." In the database grazing projects of the Bavarian Academy for Nature Conservation and Landscape Management, last updated February 23, 2010. Retrieved February 17, 2018.
  3. ↑ Walter Frisch: "Grazing project at the mouth of the Isar." Excerpts from Der Auerochs: Das Europäische Rind, Starnberg: Ed. + Verlag Ilka Frisch, 2010, ISBN 978-3-00-026764-2 . Posted January 2, 2018. Retrieved February 17, 2018.

Coordinates: 48 ° 46 ′ 31.1 ″  N , 12 ° 57 ′ 27.1 ″  E