Munster Aa

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Munster Aa
Münstersche Aa in Münster with the Aa-Uferweg

Münstersche Aa in Münster with the Aa-Uferweg

Water code EN : 332
location North Rhine-Westphalia , Germany
River system Ems
Drain over Ems  → North Sea
source In Havixbeck at the northeast slope of the tree mountains
51 ° 58 '27 "  N , 7 ° 22' 9"  O
Source height 131  m above sea level NN
muzzle At Greven in the Ems coordinates: 52 ° 5 ′ 9 ″  N , 7 ° 36 ′ 21 ″  E 52 ° 5 ′ 9 ″  N , 7 ° 36 ′ 21 ″  E
Mouth height 39  m above sea level NN
Height difference 92 m
Bottom slope 2.1 ‰
length 43 km
Catchment area 172.325 km²
Flowing lakes Aasee
Big cities Muenster

The 43 kilometer long Münstersche Aa is an orographic left tributary of the Ems .


In Westphalia , the name Aa is a widespread name for rivers and streams, which is derived from the Old High German aha (spoken: "Acha"), flowing waters , from ancient Germanic * ahwō . The word corresponds etymologically exactly to Latin aqua "water". River names of this origin can also be found in other parts of Germany, as well as in Austria, Switzerland and the Netherlands, mostly in the form Ache or Ach and often as the second part of compounds.

Course and catchment area

The sources of the Münsterschen Aa are located in northwest Westphalia about 16 kilometers west of Münster near Havixbeck . Coming from the Baumberge , the Hangsbach , Poppenbecker Aa and Krummer Bach flow in a north-easterly direction and merge near the historic Klute brewery to form the Münsterschen Aa. The Aa feeds the graves of Haus Stapel and is dammed up into ponds at the stacking mill . In the further course it flows east past Roxel , then bends to the north and is dammed in Münster to the 2.3 kilometer long Aasee . Then it flows through the city center between St. Paulus Dom and Überwasserkirche , which got its name because it is across the river from the city center. In total, the Aa runs for a length of 30 kilometers through the urban area of ​​Münster. A few kilometers north of Münster it flows into the Ems at Greven - without reaching the place directly.

The catchment area of ​​the river covers around 175 km², 104 km² of which is mainly used for agriculture.


After the end of the Second World War , a concrete river bed with a trapezoidal profile was created for the inner-city and parts of the extra-urban course of the Aa in Münster, which increased the flow speed of the water to such an extent that it was almost impossible for plants and animals to settle in this section.

The phosphate inputs from agricultural fertilizers and liquid manure into the Münstersche Aa are dramatically high, they pollute the water particularly in rural areas. In summer, phosphates in combination with strong warming of the water regularly lead to algae plague . Since 2005 there have been promising attempts to improve the water quality of the Aasee by inoculation with precipitants.


As early as the mid-1980s, thoughts on the renaturation of the river course in the area of ​​the Coerde district were raised for the first time . In 1996 work on the renaturation of the Munster Aa between the southern end of the Aasee and Haus Kump was completed. At the end of the 1990s, the concreted river bed of the Aa was removed over a stretch of around 1,600 meters and the course of the river was widened in order to prevent the risk of flooding due to the lower flow velocity. The project was completed in 2002, as was the work near Rjasanstrasse on Cheruskerring. There, the base reinforcement and the embankment of the Aa were redesigned close to nature over a stretch of 145 m. In Havixbeck , corresponding measures were completed in 2006 in the vicinity of Haus Stapel and in 2010 in the Havixbeck farmers' association in Walingen. Also in 2010, a section of 320 meters in length near Haus Coerde was renatured in order to be able to better absorb high water runoff peaks.

At the end of July 2011 it was announced that the construction of a second Aa arm was planned for the winter of the same year. This arm should run between the Kump house and the Aasee. In this way, the water should get into the Aasee more quickly, so that it can heat up less strongly due to the sun's rays, which should reduce the growth of blue-green algae . The plan approval decision and an environmental impact assessment for the restoration measures have now been completed. Only the approval from politics for this construction project is still pending. The financial means are to be drawn from the “Living Waters” program of the Münster district government . According to the city of Münster, the costs amounted to around one million euros, 80% of which were borne by the state as part of the “Living Waters” program and around 800,000 euros were lower than the originally expected costs.

From the beginning of 2012 to mid-2014, the civil engineering department of the city of Münster moved around 35,000 cubic meters of earth and set 1000 tons of armor stones.

The renaturation of the Aa near Hülshoffstrasse, federal motorway 1 and in the inner city area has been planned since 2012 . Furthermore, the river bed of the Münsterschen Aa between Haus Kump and Sentruper Straße was renatured from August 2012, for which almost one million euros was estimated, of which the state of North Rhine-Westphalia contributed around 80%. The aim is to improve the water quality of the Münsterschen Aa and the Aasee by returning the flowing water to a near-natural state and compensating for the deficits in the water structure. The city of Münster created a sand trap near Haus Kump to prevent further silting up of the Aasee. In addition, the Münstersche Aa regained its natural course over a distance of around 2.6 kilometers, with planners and engineers based on maps from 1830. The completion of the work was planned for the summer to autumn 2013.

The plan for 2014 is to ecologically improve the sub-area south of Hülshoff-Strasse up to Hülsbach by extending it by 180 meters to 1070 meters, and in this way to renature it. [obsolete] A project duration of around eight months is expected, combined with costs of 570,000 euros, of which 456,000 euros are to be borne by the state of North Rhine-Westphalia.

It is also planned to start a project to remove the inner-city concrete floor of the Aa from around 2016. [obsolete] The million dollar project is to last several decades and affect the entire inner-city river course between the Goldener Brücke, Kanalstrasse and Aasee. The triggers for the project are both structural defects, as the river bed begins to dissolve after 60 years, as well as the reduction in flow speed due to the renaturation of the river so that flora and fauna can settle again in order to improve the water quality. The aim is to achieve a water quality that enables citizens to use the Aa for swimming. In addition to logistical planning, according to information from the Münster civil engineering department, the greatest challenges of the project are to be seen in preventing the side walls from slipping off. Downstream of this project, the bridge at Spiekerhof is to be redesigned to make the Aa more visible, for which a budget of 450,000 euros is being discussed.

Twelve renaturation projects were implemented from 2000 to mid-2014.

In 2018, the Aa in the area of ​​Westerholtschen Wiese was freed from its concrete bed and ecologically upgraded over a length of 210 m. The river on the Kanalstrasse was also ecologically upgraded in 2018 and a course with floodplain structures was created.

Without further dating, further projects are planned to restore the continuity of the Aa at Beckschems Mühle (Hohenholter Straße / Schonebeck) and at the Klostermühle, for the ecological upgrading of the Aa in the Schonebeck farming community and to remove the bank reinforcement near Walingen.

Water level

On average, the Aa carries around 1000 liters of water per second in the lower reaches. However, since the Münstersche Aa has little water at times, the civil engineering department estimates that canoeists will not be able to navigate it in the future either.

In October 2013, after persistently warm and dry summer months, the water level was only 90 centimeters and thus almost 30 centimeters less than in October of the previous year. According to meteorologists, this deviation is within the normal range.

Web links

Commons : Münstersche Aa  - collection of images, videos and audio files

Individual evidence

  1. a b German basic map 1: 5000
  2. a b c Topographical Information Management, Cologne District Government, Department GEObasis NRW ( information )
  3. a b Gabriele Hillmoth: Everything is in flux: plans for Aa renaturation are gushing. In: Westfälische Nachrichten . Münster, May 31, 2014.
  4. a b c d e f g h Helmut Etzkorn: Completion of the renaturation: The Aa is a river again.  ( Page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. In: Münstersche Zeitung. Münster, June 6, 2014.@1@ 2Template: Toter Link /  
  5. a b Martin Kalitschke: Million project for the next decades - The end of the concrete Aa. In: Westfälische Nachrichten. July 20, 2011.
  6. ^ A b c d Thomas Schubert: Back to the old river bed: City of Münster is planning another renaturation project in the area of ​​the Münsterschen Aa. In: Westfälische Nachrichten. Münster / surroundings, Münster-Roxel, September 14, 2014.
  7. a b c Münster civil engineering office: Renaturation of the Münsterschen Aa near Nevinghoff , Berthold Reloe
  8. a b c d e section is being renatured: Aa gets its natural river bed back. In: Münstersche Zeitung . Münster, July 10, 2012.
  9. a b Tiefbauamt Munster: restoration of Munster Aa close Rjasanstraße , Berthold Reloe
  10. ^ Muenster civil engineering office: Ecological improvement of the Munster Aa at Haus Stapel , Hermann Mollenhauer
  11. ^ Munster civil engineering office: Ecological upgrading of the Munster Aa near Walingen , Hermann Mollenhauer
  12. Tiefbauamt Munster: Polder at home Coerde , Berthold Reloe
  13. Hope for funding from the land - the plan and decision to renaturalize the Aa are pending. In: Westfälische Nachrichten. August 5, 2011.
  14. ^ Martin Kalitschke: New Aa arm: start of construction in winter? In: Westfälische Nachrichten. July 20, 2011.
  15. ^ Munster civil engineering office: Renaturation of the Munster Aa Sentruper Str. To Aasee , Berthold Reloe
  16. ^ Munster civil engineering office: renaturation of the Munster Aa near Hülshoffstrasse , Berthold Reloe
  17. ^ Munster civil engineering office: Renaturation of the Munster Aa near the A1 motorway , Berthold Reloe
  18. ^ Munster civil engineering department: Ecological upgrading of the Munster Aa in the inner city area , Berthold Reloe
  19. a b c d e Thomas Schubert: Back to the old river bed: The Aa will be renatured in the area between Sentruper Straße and Haus Kump by autumn. In: Westfälische Nachrichten. Münster / surroundings, Münster-Mecklenbeck, February 16, 2013.
  20. Klaus Baumeister: Destructive criticism of bridge plans: District representatives find Spiekerhof concept primitive. In: Westfälische Nachrichten. Münster, October 12, 2011.
  21. EC Water Framework Directive in Münsterland | Redesign of the Münsterschen Aa on the Westerholtschen Wiese. Retrieved March 16, 2020 .
  22. EC Water Framework Directive in Münsterland | Münstersche Aa - ecological improvement and flood protection. Retrieved March 16, 2020 .
  23. ^ Munster civil engineering office: restoring the continuity in the Munster Aa near Beckschems Mühle , Hermann Mollenhauer
  24. ^ Munster civil engineering office: Restoring the continuity in the Munster Aa at the Klostermühle , Hermann Mollenhauer
  25. ^ Munster civil engineering office: Ecological upgrading of the Munster Aa near Schonebeck , Hermann Mollenhauer
  26. ^ Munster civil engineering office: Removal of the bank reinforcement in the Munster Aa near Walingen , Hermann Mollenhauer
  27. a b Martin Kalitschke: On dry land: After the super summer, many rivers and lakes have little water. In: Westfälische Nachrichten. Münster, October 9, 2013.