Bünz
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Bünz upper course name: Rüeribach |
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 Renatured section of the Bünz near Dottikon |
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| Data | ||
| Water code | CH : 681 | |
| location |
Mittelland
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| River system | Rhine | |
| Drain over | Aabach → Aare → Rhine → North Sea | |
| source | in the Cholmatt at Hintergrüt farm above Winterschwil 47 ° 14 ′ 34 ″ N , 8 ° 19 ′ 26 ″ E |
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| Source height | 711 m above sea level M. | |
| muzzle | near Möriken-Wildegg in the Seetaler Aabach Coordinates: 47 ° 25 '1 " N , 8 ° 9' 54" E ; CH1903: 654 806 / 252052 47 ° 25 '1 " N , 8 ° 9' 54" O |
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| Mouth height | 348 m above sea level M. | |
| Height difference | 363 m | |
| Bottom slope | 14 ‰ | |
| length | 26 km | |
| Catchment area | 122.61 km² | |
| Discharge at the estuary A Eo : 122.61 km² |
MQ Mq |
2.25 m³ / s 18.4 l / (s km²) |
| Left tributaries | Sörikerbach, Chräbsbach, Wissenbach, Holzbach, Krebsbach | |
| Right tributaries | Altbach, Lippertwiesbach, Schwarzgraben, Hägglingerbach | |
| Small towns | Well | |
The Bünz is a 26 kilometer long river in the Swiss canton of Aargau and a right tributary of the Seetaler Aabach . It crosses the Aargau districts of Muri , Bremgarten and Lenzburg from south to north .
geography
course
The source of the Bünz is located in Freiamt above Winterschwil am Lindenberg at an altitude of around 711 m above sea level. M. The creek begins in an open agricultural area between the hamlets Geltwil and Brunnwil . At Isenbergschwil it takes up the Altbach from the right , which rises south of Brunnwil on the Lindenberg and used to drive a mill at Winterschwil. Now the stream, which in this section also bears the name Rüeribach , flows down in a small valley to the Langdorf part of the village of Muri , where there was another watermill, and continues through the Muri settlement on the former Kirchfeld at 460 m above sea level. M. in the wide alluvial and marsh landscape east of Boswil . The Sörikerbach flows into the Bünz from the left at Muri and the Wissenbach from the left at Bünzen . Several drainage ditches lead to the Bünz from the humid plain between Muri and Besenbüren , which was important for the extraction of peat in the 20th century, especially the Krebsbach and the Schwarzgraben. Since the dumping projects, the Bünz itself has also been in an artificial, deep ditch, which was continued in the 20th century via Waltenschwil and Wohlen to Othmarsingen .
Between Anglikon and Dottikon , the Bünz receives the Holzbach as another major tributary , which arises from several streams near Sarmenstorf and Büttikon . At Dottikon it leaves the formerly swampy plain and flows into a narrow valley that it has cut into the layers of gravel. The slope near Dottikon was previously used by two waterworks, the mill in the village and the Tieffurtmühle northwest of it. Othmarsingen also owned a mill and a sawmill by the water.
To the northwest of Othmarsingen, the Bünz is overturned under the wide embankment of the Zurich - Lenzburg railway line . After a final stretch of about 4 kilometers in length with a much stronger fall it joins Wildegg the old industrial district of the right as the greatest side stream in the Seetal Aabach just before this railway line Aarau - Brugg underpasses and 250 meters further down the Aare flows .
Catchment area
The 122.61 km² catchment area of the Bünz lies in the Swiss Plateau and is drained to the North Sea via the Aabach, the Aare and the Rhine .
It consists of 26.6% planted area , 56.9% agricultural area , 16.1% settlement area and 0.3% water area.
The mean height of the catchment area is 520 m above sea level. M. , the minimum height is 347 m above sea level. M. and the maximum height at 877 m above sea level. M.
Hydrology
At the confluence of the Bünz in the Aabach, their modeled mean flow rate (MQ) is 2.25 m³ / s. Her discharge regime type is pluvial inférieur and her discharge variability is 25.
Flow corrections
Because of the gentle slope, the brook used to meander very strongly, and the area north of Wohlen was a large swamp . In the 1920s, the Bünz between Muri and Othmarsingen was straightened and canalized. This prevented the floods that used to occur frequently. The swamp was drained and made usable for agriculture . However, the straightening and lack of sewage treatment plants in increasingly industrialized communities resulted in the extinction of many animal species. This contributed to the fact that the Bünz was considered the dirtiest body of water in the canton of Aargau.
In the municipal area of Möriken-Wildegg, shortly before the confluence with the Aare, the Bünz was not straightened during the corrections, but here too the stream was fortified with barriers that prevented any dynamism. But this changed suddenly with the flood of the century in May 1999: within hours the Bünz eroded all banks and created a completely new bed. A dynamic meadow landscape with large, freshly created gravel areas was created from the former agricultural area, which was populated by pioneer vegetation . The Federal Office for the Environment recognized the resulting Bünzaue Möriken in 2000 as a floodplain area of national importance .
Renaturation
Since 2001, renaturation measures have been taken at various points . The watercourse was not changed, but barriers were removed and obstacles such as stone barriers, tree stumps or gravel were added. The width of the stream bed was also increased when the water level was high. These measures are intended to reduce the flow velocity, improve flood protection and enable the displaced aquatic life to be resettled. The rehabilitation of the sewage treatment plants in the region improved the water quality and increased the population of fish and small organisms. Numerous brown trout can be observed in previously heavily polluted areas.
Web links
- The fish fauna in the Bünz (PDF file; 478 kB)
- Description of a renaturation project (PDF file; 114 kB)
- Bünzaue near Möriken-Wildegg
Individual evidence
- ↑ a b c Geoserver of the Swiss Federal Administration ( information )
- ↑ a b c d Modeled mean annual discharge. In: Topographical catchment areas of Swiss waters: sub-catchment areas 2 km². Retrieved August 9, 2017 .
- ↑ "Hidden behind the mean values" - the variability of the discharge regime , p. 7
- ↑ The discharge variability describes the extent of the fluctuations in the mean discharge of individual years around the long-term mean discharge value.