Eyelet

from Wikipedia, the free encyclopedia
Eyelet
The Ösper flows to the Weser via a bed slide in the harbor

The Ösper flows to the Weser via a bed slide in the harbor

Data
Water code EN : 4732
location North Rhine-Westphalia , Lower Saxony ; Germany
River system Weser
source In Nordhemmern
52 ° 20 ′ 22 ″  N , 8 ° 48 ′ 18 ″  E
Source height 54  m above sea level NN
muzzle In Petershagen in the Weser Coordinates: 52 ° 22 ′ 50 ″  N , 8 ° 58 ′ 18 ″  E 52 ° 22 ′ 50 ″  N , 8 ° 58 ′ 18 ″  E
Mouth height 35  m above sea level NN
Height difference 19 m
Bottom slope 1.3 ‰
length 14.5 km
Catchment area 72.649 km²

The Ösper is an approximately 15-kilometer-long tributary to the left of the Weser on the northern border of North Rhine-Westphalia in the Minden-Lübbecke district . Their catchment area is in the north German lowlands . Like most of the rivers in the lowlands, the Ösper was straightened and turned into a natural body of water.

course

The Ösper rises in the municipality of Hille in the district of Nordhemmern and flows with a north-easterly course at Holzhausen II into the urban area of Petershagen , where it first crosses the districts of Friedewalde , Südfelde and Meßlingen . In Maaslingen it then turns east to the Weser lowlands. The section between Eldagsen and the Petershagener core town is characterized by a steep valley section in which the stream ran with numerous meanders before it was straightened . In the core town of Petershagen, the Ösper finally flows into the Weser in the former port.

geology

Due to its location in the North German lowlands, the approximately 73 km² catchment area of ​​the Ösper is predominantly characterized by sandy and gravelly deposits from the Ice Age, partly also by clays from the Cretaceous period , which occur in some places in the layers close to the surface.

The classification of flowing waters according to ecoregions and, within the regions, according to the geology of the catchment area, used by the EU Water Framework Directive (WFD), assigns the Ösper to the sand -shaped lowland stream (Petershagen to Friedewalde) and the organic low-lying stream (Friedewalde to Nordhemmern). However, there are different characteristics depending on the small-scale available substrate.

Tributaries

The Ösper has 10 tributaries on the right, including the Rhien (7.7 km), Südfelder Bach (3.5 km) and Tappenauer Bach (2.3 km), as well as 12 tributaries on the left, including the swamp moor ditch (4.0 km) and the Meßlinger Bruchgraben (1.8 km), Striethorngraben (2.2 km), and Teichgraben (1.7 km).

Interventions in the habitat

In the past, the natural structures of the Ösper were changed to improve agricultural use. Historical maps show that the flowing water was straightened at the beginning of the 20th century except for the larger meanders in the lower reaches between Eldagsen and Petershagen. The relocation of the course and measures to drain the Große Aue improved or enabled pasture and meadow management in the lowlands. As a species-rich wet meadow , the grassland was still widespread in the Öspers catchment area in the 1950s. A complete straightening of the Ösper with a trapezoidal expansion of the brook bed, fortification of the banks with stone pouring and the construction of bedfalls took place around 1970. The discharge of the entire amount of water during floods was the prerequisite for the use of arable land in Öspertal.

This massive intervention in the morphological structures of the flowing water impaired or destroyed the habitat of the animals and plants typical of the water and floodplain. In particular, the 3 m high bottom plunge in the former harbor, which existed until 2014, was an obstacle for aquatic animals that could only be overcome during floods. The assessment of the water structure quality in the inventory of 2009 and 2013 of the EC WFD shows that the Ösper is one of the very heavily and partly completely changed rivers in the overall assessment (status class VI or VII of the seven-stage scale). The poor structural quality consequently affects the river communities. According to the 2009–2011 water monitoring, the Ösper does not achieve the “good ecological status” required by the WFD, which primarily includes the found communities of macrozoobenthos, fish and aquatic flora. After that it is in a bad or unsatisfactory ecological condition.

Until 2008, the discharge of the treated seepage water from the Pohlsche Heide district waste disposal site was a major burden for the Ösper . It is now being discharged directly into the Weser.

Renaturation

A 1.2 km long Ösper section in Petershagen-Kernstadt was ecologically improved in 2014. This is intended to achieve the “good ecological status” required by the EU WFD for this area. The following measures were carried out:

  • Creation of patency by removing the 3 floor falls and building a 90 m long floor slide in the harbor to allow fish and small animals to migrate upwards
  • Removal of the bank reinforcement (stone fill) at suitable sections in order to allow a dynamic development in the form of erosion and sedimentation processes again.
  • Creation of two replacement meadows with initial channels and oxbow lakes. There the water should find its own way.
  • Introduction of dead wood, which contributes to a diverse river bed and z. B. promotes the formation of scour.
  • Planting of riparian trees
  • Redesign of the underpass for the L 770

history

Ösper as a fortress moat

In the 14th century, a castle was built on the banks of the Weser near the Ösper tributary, today's Petershagen Castle . The protective function for the castle and the newly created settlement was taken over from two sides by the Ösper, which was converted into a fortress moat. The water had to be specially relocated beforehand. In the 1960s it still flowed through the town in an arched, about 900 m long fortified ditch and flowed into the Weser below the castle. The original course of the Ösper can no longer be determined because the fortress moat has been changed many times. Around 1970 the flowing water was removed from the town center. Since then, the Ösper has been flowing on the northern outskirts to the former port, which is located downstream near the previous mouth of the Ösper. The relocation took place in connection with the expansion of the Ösper. The historical protective ditch was partially filled in, but some of it has been preserved as a relic. There is still the old section of the estuary with its pollarded willows on the bank, which enriches the landscape there as a cultural landscape element.

Watermill

For several centuries there was a water mill on the lower reaches of the Ösper. The mill was torn down, and the ponds have also disappeared. Today the dam of Landesstraße 770, which leads to the Weser Bridge, is located there.

literature

Web links

Commons : Ösper  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b German basic map 1: 5000
  2. ↑ a b Topographical Information Management, Cologne District Government, Department GEObasis NRW
  3. ^ Geological map of North Rhine-Westphalia 1: 25 000. Sheet 3619 Petershagen. Geological Survey North Rhine-Westphalia 1965
  4. ↑ River type maps in ELWAS-WEB, Department of Surface Waters Typology-Typology of Rivers LAWA, accessed on April 10, 2015
  5. ↑ Water directory of the State Office for Nature, Environment and Consumer Protection NRW - PDF, 1 MB
  6. ↑ Draft for the regulation of the Ösper and the improvement of the Öspertal and its side valleys and the Landerbach valley, 1: 5,000, 1911/12
  7. ↑ Prussian map recording, measuring table sheets 1: 25,000, 3619 Petershagen, 1898 and continuation stands
  8. ^ Sofie Meisel: The natural space units on sheet 85 Minden. Natural division of Germany. Remagen 1959
  9. ↑ Kornelia Fieselmann: The catchment area of ​​the Ösper. Ecological and historical aspects of a brook landscape in Petershagen. Editor of local home maintenance Petershagen. Petershagen 2008
  10. ↑ http://gewinfo.fisdt.de/4732/ (link not available)
  11. ↑ Water structure maps in ELWAS-WEB, Department of Surface Waters - Water Structure, Overall Assessment, accessed on April 10, 2015
  12. ↑ Detmold district government, profiles of the planning unit Weser NRW, see planning unit Mittelweser accessed on April 10, 2015
  13. ↑ Kornelia Fieselmann: The catchment area of ​​the Ösper. Ecological and historical aspects of a brook landscape in Petershagen. Editor of local home maintenance Petershagen. Petershagen 2008
  14. ↑ Explanation of the geological map of North Rhine-Westphalia 1: 25 000. Sheet 3619 Petershagen. Geological Survey North Rhine-Westphalia 1965