Trollhättan Falls in Göta älv
|- elevation||44 m (144 ft)|
|- elevation||0 m (0 ft)|
|Length||93 km (58 mi) 1|
|Basin||50,229.3 km2 (19,394 sq mi) |
|- average||575 m3/s (20,306 cu ft/s) |
|1: 720 km including Klarälven and Vänern |
The Göta älv is a river that drains lake Vänern into the Kattegat, at the city of Gothenburg, on the western coast of Sweden. It was formed at the end of the last glaciation, as an outflow channel from the Baltic Ice Lake to the Atlantic Ocean and nowadays it has the largest drainage basin in Scandinavia.
The Göta älv is located in Götaland, with the river itself being a site of early Geatish settlement. The length is 93 km. Usually the combination of Göta älv and Klarälven (a river ending at Vänern) is considered to be one river system. This combination is the longest river in the Nordic countries, 750 km. The Bohus Fortress is located by the river at Kungälv. Here the river splits into two, with the northern part being the Nordre älv and the southern part keeping the name Göta älv.
At Trollhättan there is a dam, canal locks and a hydropower station in the river. The locks make the river navigable, even for large cargo vessels (88 m long). The artificial parts are called Trollhätte Canal. The river and the canal is part of a mostly inland waterway, Göta Canal, which spans the width of Sweden to the Baltic Sea south of Stockholm.
The power station supplied electric power to the heavy steel industry concentrated around Trollhättan Falls, contributing to its industrial revolution. In the summer months the spillway of the dam is opened for a few minutes daily and tourists gather to see the water rushing down the river (picture).
There are concerns about whether the maximum discharge of 1000 m³/s is enough in a scenario where heavy rain floods the lake Vänern, causing considerable damage. Previously this was thought not to be possible in reality, but in 2001 the lake was flooded almost a meter above maximum level (and some upstream lakes like Glafsfjorden 3 metres). In this situation, Göta älv was allowed a discharge of 1100 m³/s for months causing big risk of landslides. Now a water tunnel between Vänersborg and Uddevalla is considered as a rescue solution.
There is a large risk of landslides along the river and historical notes of 15 landslides exist. The largest occurred in the years 1150, 1648, 1950, 1957 and 1977 (Tuve landslide).