Engelberger Aa

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Engelberger Aa
upper course name: Stierenbach
lower course: Aawasser
Ground fog over the Engelberger Aa

Ground fog over the Engelberger Aa

Data
Water code CH : 720
location Switzerland
River system Rhine
Drain over Reuss  → Aare  → Rhine  → North Sea
source a little south of the Surenen Pass
46 ° 50 ′ 1 ″  N , 8 ° 32 ′ 49 ″  E
Source height approx.  2240  m above sea level M.
muzzle near Buochs in Lake Lucerne Coordinates: 46 ° 58 ′ 44 ″  N , 8 ° 25 ′ 32 ″  E ; CH1903:  675 087  /  203569 46 ° 58 '44 "  N , 8 ° 25' 32"  O
Mouth height 434  m above sea level M.
Height difference approx. 1806 m
Bottom slope approx. 48 ‰
length 38 km
Catchment area 229.07 km²
Discharge
A Eo : 228 km²
Location: 1.7 km above the mouth 		NNQ (2006)
MNQ 1916–2016
MQ 1916–2016
Mq 1916–2016
 MHQ 1916–2016
HHQ (2005) 		340 l / s
8.78 m³ / s
12.5 m³ / s
54.8 l / (s km²)
 15.8 m³ / s
230 m³ / s
Engelberger Aa (Switzerland)
source
source
muzzle
muzzle
Source and mouth of the Engelberger Aa

The Engelberger Aa ( Swiss German Aa for Ache ) is a 38 km long mountain river in the central Swiss cantons of Uri , Obwalden and Nidwalden . In Nidwalden the river is also called Aawasser .

course

In its upper part, the Engelberger Aa is called Stierenbach . This high mountain stream rises west of the 2291 meter high Surenen Pass in the canton of Uri . It follows the course of the valley called Surenen in a south-westerly direction and crosses the wide, 1770 m high basin of the Blackenalp . Below the Blackenalp, at an altitude of 1630 m, the stream in the Stäuber waterfall falls over a step in the terrain. Between the Schlossberg and the Spannort chain on the left and the high terrace of Alp Äbnet on the right, it crosses the still treeless high valley of Alp Stäfeli . A few meters below the Alpenrösli inn , it leaves the Uri region at an altitude of around 1250 m.

At this eastern end of the Engelberg exclave of Obwalden, an alluvial forest lines its course. Then the brook flows, grazing the mighty northeast pillar of the Titlis , through a notched valley and then past the Alp Herrenrüti , located between Titlis and the vertical wall of the Fürenalp . At around 1080 m above sea level, at the valley station of the Fürenalp cable car, the Engelberger Aa reaches the populated part of the Engelberg municipality. Your gradient will now noticeably decrease. On the other hand, the stream has become a considerable river due to the many tributaries from the mountain ranges on both sides of its upper reaches. After downpours and when the snow melts, it is torrential and dangerous.

There are also considerable tributaries from the local mountain Hahnen , the mountains to the north above the side valley Ende der Welt and the Brunni , especially the Bärenbach, which rises from the scree fields under the Laucherenstock and over the Planggenstafel and through the hamlet of Horbis flows down to Engelberg. The wide high valley near Engelberg (1015 m) goes back to the silting up of an extensive reservoir, which was created at the end of the last Ice Age by a huge landslide of the Titlis and was later filled with gravel and sand. A remnant of this is the Eugenisee at the western end of the valley level, the water of which is used to generate electricity. A part of the water of the Aa serves to feed and regulate this lake.

Below this semi-artificial mountain lake, the Aa falls down into the Aatobel, in the course of which it turns north. The steep terrain is subject to severe erosion to this day , and isolated landslides occur again and again. In this section tributaries come down from the Titlis massif and the Huetstock area; the largest of these is the Trüebenbach, which drains the Trüebsee .

At the exit of the Schwändiloch gorge , the Aa reaches the compensation basin for the Dallenwil power station near Obermatt under the Zingelflue . It then flows between the rock face at Hinterrugisbalm and the debris fan of the Eugenibach down to Mettlen. Now the Aa is flowing again through an alluvial forest in a wide bed that has been filled with considerable amounts of rubble and debris since the floods in 2005 . At the hamlet of Grafenort, which still belongs to the Engelberg community, it reaches the wide valley floor of the lower Engelberg valley . In this section it forms the border between Obwalden area on the right and Nidwalden area on the left. 500 m north it finally crosses over to Nidwalden. It now mostly flows between meadows on the flat valley floor, but still with a considerable current. It crosses the communities Wolfenschiessen and Dallenwil , flows past Büren and Oberdorf . From here on the river is also known as Aawasser . To the east of Stans , the river turns to the east, where it touches the municipal boundary of Stans. Shortly after the former power station of the Bürgenstock railway company in Eggertsbüel that existed 1888-1996, the Aa underpass next to the old Fadenbrücke the main road and the highway A2 and flows next to the airfield Buochs by Buochser Allmend and then on the edge of the village settlement of Buochs ​​in Lake Lucerne . The Am Aawasser power station is 700 meters from the estuary .

  • Dusters

  • Alluvial forest on the upper reaches, view of the Schlossberg

  • The waterfall on the Eienwäldli brings water from the tap to the Aa

  • Aatobel

  • Double suspension bridge in the lower Aaschlucht

  • Obermatt hydropower plant

  • Bulwark against mudslides at the exit of a side valley near Wolfenschiessen

  • Valley exit

  • Thread bridge

Flood of 1471

Only since the floods of 1471 did the Engelberger Aa flow in its current bed to its confluence with Lake Lucerne near Buochs . Before that, the river at Oberdorf divided into three arms - one poured into Lake Lucerne near Stansstad, a second flowed into the marshy reed landscape near Ächerli and the third arm snaked past the Buochserhorn to Buochs. The debris from the flood of 1471 buried the two side arms and thus achieved the political solution of a river diversion that had been sought in the Nidwalden rural community in 1462, but which was not implemented due to the resistance of the Buochs ​​peasants. Major corrective measures began throughout the 20th century, triggered by the floods of 1910. If damage were to occur today as in 1910, the Federal Office for Water and Geology expects damage of up to CHF 100 million.

2005 flood

During the floods in August 2005 , the Engelberger Aa flooded almost the entire valley floor of Engelberg after days of rain. Extensive evacuations were required. The main road in the valley and the railway line were badly damaged; At the upper end of the Aaschlucht the common viaduct, over which they led, was torn away by the water. The place was only accessible by air for two weeks. A few landslides also occurred, the tracks at Obermatt train station were buried, and a dam was in danger of breaking at the compensation basin of the Obermatt power station. The 2005 flood was the strongest in about 100 years and flooded about 500 hectares of land.

tourism

From the source at the Surenen Pass to Dallenwil in the lower Engelberg Valley, the Aa is lined with varied paths. Some of these are mountain hiking trails, in the flatter passages there are also comfortable walking trails such as the shady Professorenweg in Engelberg , which runs along the wooded banks . The path on the valley floor of the Aaschlucht, directly in the ravine, has not been passable since the floods in 2005. Instead, hikers are led down the steep valley through the farm road in the forest above the gorge, before reaching the bottom of the valley again above Obermatt.

For adventure vacationers, the Aa sometimes serves as a territory for white water rafting with the rubber boat. Some of the deeply cut side valleys are also popular areas for rafting .

bridges

The Engelberger AA crosses over 50 bridges from the source at the Surenen Pass to the mouth at Buochs ​​in Lake Lucerne.

See also: List of bridges over the Engelberger Aa

Web links

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

Individual evidence

  1. ↑ a b Geoserver of the Swiss Federal Administration ( information )
  2. ↑ Evaluations of the water network. (XLSX) FOEN , December 2013, accessed on August 9, 2017 (listing of Swiss rivers> 30km).
  3. ↑ Modeled mean annual discharge. In: Topographical catchment areas of Swiss waters: sub-catchment areas 2 km². Retrieved August 31, 2017 .
  4. ↑ Buochs ​​airport measuring station 1916–2016 (PDF) Federal Office for the Environment FOEN
  5. ↑ Aawasser. In: ortsnames.ch. Retrieved January 29, 2019 .