Nidelva (Agder)

Nidelva is the main river in the Arendal drainage basin in Agder county, Norway. The 221.7-kilometre (137.8 mi) long river begins at the confluence of two rivers: Nisserelva and Fyreselv. The confluence is located by the village of Haugsjåsund in Nissedal municipality in southern Vestfold og Telemark county. The river flows south into the Skagerrak at the city of Arendal. The watershed covers 4,011 square kilometres (1,549 sq mi) and has an average waterflow of 114.4 cubic metres per second (4,040 cu ft/s) at Rykene near the mouth. The highest waterflow ever recorded on the river was 1,200 cubic metres per second (42,000 cu ft/s) in the autumn of 1987.

This article is about the river in Agder and Telemark, Norway. For the river which runs through Trondheim, see Nidelva.

Nidelva
Nidelva near Blakstad in Froland
Location of the river Show map of Agder Nidelva (Agder) (Norway) Show map of Norway
Location
Country	Norway
Counties	Agder, Vestfold og Telemark
Municipalities	Grimstad, Arendal, Froland, Åmli, Nissedal
Physical characteristics
Source	Confluence of Nisserelva and Fyresdalsåna rivers
• location	Haugsjåsund, Nissedal, Vestfold og Telemark
• coordinates	58.9406°N 08.5011°E / 58.9406; 08.5011
• elevation	160 metres (520 ft)
Mouth	Skaggerak
• location	Arendal, Agder
• coordinates	58.4349°N 08.7137°E / 58.4349; 08.7137
• elevation	0 metres (0 ft)
Length	221.7 km (137.8 mi)
Basin size	4,011 km^2 (1,549 sq mi)
Discharge
• location	Rykene, Arendal
• average	114.4 m^3/s (4,040 cu ft/s)
Basin features
River system	Arendalvassdraget
Tributaries
• left	Karlsåna, Katteråsåna
• right	Blekevja, Gjøv, Sigridneskilen, Songeelva, Trevann, Rore
Waterbodies	Nelaug
Waterfalls	Kastefossen

Watercourse

The river flows through Nissedal in Vestfold og Telemark county briefly before entering Agder county. It then flows through Åmli municipality. The river Gjøv joins the Nidelva there. The large lake Nelaug is a man-made lake along the river that is used for power generation. It continues through Froland municipality and then Arendal municipality. For a while, the river forms the border between Grimstad and Arendal municipalities. The river empties into the Skaggerak just northeast of Rykene in the town of Arendal between the mainland and the island of Hisøya.[1]

There are sixteen hydro-electric power stations are built along the river, making this one of Norway's most controlled drainage systems. The largest on the river are at Rygene in Grimstad, Evenstad in Froland, and Jørundland in Åmli.[1] Salmon can be found from the mouth to as far as 22 kilometres (14 mi) up the river, where the Evenstad power station is located, effectively blocking their path further upstream.[2]

Name

The name of the river possibly comes from the Old Norse word niðr which means "the river that is lying down". It may also come from the Latin word nitere. The name of the river also may lend itself to several other local names along the river such as Nisser, Nedenes, and Nelaug.[1]

Media gallery

• 
  View of the River Nid by John William Edy
• 
  Froland Church located along the river Nidelva
• 
  View of the river in Arendal
• 
  View of the river near Gjermundsnes in Åmli
• 
  Åmfossen power station along the river in Åmli
• 
  Furre bridge over the river in Froland

References

1. Thorsnæs, Geir, ed. (2017-03-22). "Nidelva – elv i Aust-Agder". Store norske leksikon (in Norwegian). Kunnskapsforlaget. Retrieved 2017-11-09.
2. Finstad, A.G; Økland, F.; Thorstad, E.B.; Heggberget, T.G. (2005-10-06). "Comparing upriver spawning migration of Atlantic salmon Salmo salar and sea trout Salmo trutta". Journal of Fish Biology. 67 (4): 919–930. doi:10.1111/j.0022-1112.2005.00792.x.

External links

• Media related to Nidelva at Wikimedia Commons
• Evenstad power station (in Norwegian)