Big Melchaa
Big Melchaa | ||
The Grosse Melchaa in Ranft , around 1825 |
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Data | ||
Water code | CH : 711 | |
location | Canton of Obwalden ; Switzerland | |
River system | Rhine | |
Drain over | Sarner Aa → Reuss → Aare → Rhine → North Sea | |
confluence | from Cheselenbach and Bettenalpbach near Hugschwendi 46 ° 48 ′ 7 ″ N , 8 ° 17 ′ 6 ″ E |
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Source height | 1026 m above sea level M. | |
muzzle | between Sachseln and Sarnen in the Sarnersee Coordinates: 46 ° 52 ′ 52 " N , 8 ° 14 ′ 29" E ; CH1903: 661 195 / 192527 46 ° 52 '52 " N , 8 ° 14' 29" O |
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Mouth height | 469 m above sea level M. | |
Height difference | 557 m | |
Bottom slope | 30 ‰ | |
length | 18.5 km | |
Catchment area | 72.58 km² | |
Discharge at the mouth of the A Eo : 72.58 km² |
MQ Mq |
3.49 m³ / s 48.1 l / (s km²) |
The Grosse Melchaa (also Melchaa for short , Aa for Ache in Swiss German ) is an 18.5 km long tributary of the Sarnersee in the canton of Obwalden in central Switzerland .
course
The Melchaa arises as an outflow of the Melchsee in the summer and winter sports resort Melchsee-Frutt and flows through the Melchtal towards the north. At the level of the village of Flüeli-Ranft , the Melchtal narrows into the Ranft gorge . The Melchaa leads past the two Ranft chapels of Niklaus von Flüe . Shortly afterwards, the Melchaa flows under the Hohe Brücke at a depth of 100 m . The Melchaa finally follows an artificially displaced river bed and flows into the Sarnersee between Sachseln and Sarnen . Originally the Melchaa flowed along the outskirts of Sarnen and only north of Sarnen into the Sarner Aa . For reasons of flood protection, the course of the river was relocated in 1880.
Power generation
From the Melchsee , the water first flows through a pressure pipe into the Hugschwendi power plant 830 m below, where it drives two Pelton turbines with an output of 7 MW each to generate electricity. The power plant was commissioned in 1957. Previously (since 1904) the water from the Melchsee was used by the Stäubiloch turbine system . Originally the water flowed through the dust hole into a karst cave .
In the village of Melchtal , the Melchaa is slightly dammed by a small barrage (water catchment). Most of the water flows from here through an underground tunnel into the Kleiner Melchtal further south, and from there through a reservoir tunnel into the Marchgraben surge chamber and apparatus chamber. From there, the water reaches the Unteraa power station in Giswil via a pressure line , where it is turned into electricity by the Obwalden electricity station.
Flood
The flood in August 2005 caused considerable damage along the course of the Melchaa, for example a railway bridge was destroyed and a 16 kV line fell into the river. In the Acherlibach area, a large-scale, deep landslide of around 200,000 m³ occurred. The canton road was torn away over a length of around 30 m. Around a third of the material was pushed into the Melchaa, which accumulated accordingly.
Web links
Individual evidence
- ↑ a b Geoserver of the Swiss Federal Administration ( information )
- ↑ a b Modeled mean annual discharge. In: Topographical catchment areas of Swiss waters: sub-catchment areas 2 km². Retrieved August 13, 2017 .
- ↑ Stäubiloch memorial plaque ( Memento of the original from May 18, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Information page in the website of the Foundation “Natural Heritage Karst and Caves Obwalden” (NeKO) from September 29, 2004, accessed on September 17, 2012
- ↑ Government Council of the Canton of Obwalden: Report on dealing with the flood disaster 2005 (PDF; 350 kB)