Engelberger Aa

Ground fog over the Engelberg Aa

The Engelberg Aa (Swiss German for Ache Aa ) is a 37 km long mountain river in the central Swiss cantons of Uri, Obwalden and Nidwalden. He gives the Engelberg valley its name.

Course

In its upper part the Engelberg Aa Stierbach is called. This high mountain stream originates west of the 2291 meter high Surenenpass in the canton of Uri. It follows the course of the Surenen called valley south-west and crosses the wide, 1770 m high boiler Blackenalp. Below the Blackenalp, in 1630 m height, the stream tumbles down in waterfall duster over a terrain level. Between the Schlossberg and the Spannort chain on the left and the high terrace of the Alp Äbnet on the right, he crosses the still treeless high valley of Alp Stäfeli. A few meters below the inn Alpenrösli he leaves at around 1250 meters altitude Uri area.

At this eastern end of the Engelberg exclave of Obwalden initially a floodplain fringed its course. Then the stream, the mighty north-east pillar of the Titlis flows grazing by a V-shaped valley and then between Titlis and the vertical wall Fürenalp situated on the Alp Herrenrüti over. At around 1080 m altitude at the valley station of the cable car Fürenalp, the Engelberg Aa reaches the populated part of the Engelberg municipal area. Your gradient now decreases noticeably. On the other hand, the creek has become by the many tributaries of the mountain ranges on either side of its upper reaches to a considerable river. After rains and the snow melts he's tearing and dangerous.

Also on the populated municipality added yet substantial inflows from mountain valves, the northern mountains above the side valley end of the world and the Brunni. The broad upland valley to Engelberg (1015 m) is due to the silting up of a vast artificial lake, which was created by a massive landslide of Mount Titlis at the end of the Ice Age and was later filled by gravel and sand. Residue thereof, the Eugenisee is at the western end of the valley whose water is used for electricity generation. Part of the water of the Aa serves to feed this lake and regulate.

Below this semi-artificial mountain lake plunges the Aa in the Aatobel, during which it turns north. The steep terrain level is still subject to severe erosion and occasional landslides. In this section there are links inflows from the Titlis massif and from the Huet floor area. From right water comes from the Brunni and the overlying mountains. At the end of the gorge the Aa reaches the catch basin of the power station Obermattstrasse.

Below Obermattstrasse it flows through a wide bed that is filled with substantial amounts of debris and rubble since the flood in August 2005, again by a riparian forest. When Mr. Grafenort, which still belongs to the municipality Engelberg, they reached the wide bottom of the lower Engelbergertals. In this section, it forms the border between Obwaldner area on the right and Nidwaldner area on the left. 500 m north it occurs finally move to Nidwalden. You now flows mostly between meadows on the flat valley floor, but still with considerable flow. It passes through the municipalities Wolf shooting and Dallenwil, flows past Buren and Oberndorf. East of Stans makes a bend to the east. Below the Buochserhorns over flowing, they finally reached Buochs, where it empties into Lake Lucerne.

Floodplain in the upper reaches, facing the Schlossberg Mountain

The waterfall at Eienwäldli brings water from the taps to the Aa

Aatobel

Suspension bridge in the lower Aaschlucht

Hydropower plant Obermattstrasse

Bulwark against debris flows on output of a side at Wolf shooting

Valley exit

Tourism

From the source on Surenenpass until after Dallenwil in the lower valley of Engelberg Aa is lined with varied ways. These are partly mountain trails, in the shallower passages also convenient for walking trails such as the shady, wooded banks along the leading Professorenweg in Engelberg. However, the path to the bottom of the Aaschlucht, directly on the ravine along is no longer viable, since the 2005 flood. Hikers will instead by the service road in the forest above the ravine led down the steep valley before they reach just above the upper Matt bottomed out again.

For adventure travelers, the Aa sometimes serves as a spot for white water rafting with the dinghy. Some of the deeply incised valleys are also popular areas for rafting.

2005 flood

In the flood of August 2005, the Engelberg Aa flooded after days of rain almost the entire valley of Engelberg. Extensive evacuations were necessary. The main road of the valley and the railway line were severely damaged; at the upper end of the Aaschlucht was the common viaduct over which they led, swept away by water. The location was accessible for two weeks only by air. Also, some landslides occurred, the tracks of the train station Obermattstrasse were spilled, and the balancing reservoir of the power station of Upper Matt threatened a dam failure. The flood of 2005 was the strongest for about 100 years and flooded about 500 acres of land.