Jokulsa a Dal, also called Jokulsá á Bru or Jokla as many people call it, is the longest river of Eastern Iceland, about 150 km, with a discharge area of about 2610 km² and a volume of 152 m³/sec. It deposits about 120 tons of silt in the delta area per hour. Its main discharge, Bruarjokull, is the largest glacier tongue of the icecap Vatnajokull. Gigantic advances of this glacier snout can be expected every 60-80 years.
The River Jokla, the glacier’s main discharge, is still eroding one of the wildest and deepest canyons of the country, Dimmugljufur and Hafrahvammagljufur. Down in the lowlands, the silt deposits are constantly reshaping the coastline.
According to old sources there was a natural stone arch across the river in the vicinity of the farm Bru (Bridge), but man made bridges existed from the earliest epochs of history.
The first concrete bridge was built in 1931 and a new one on road # 1 in 1995. Cable carriers have existed at least from the 18th century and the last one has not been used since 1972, but still exists. Quite a few fatal accidents occurred in connection with the cable carriers. Altogether five bridges simplify communications in the Glacial Valley (Jokuldalur) now-days.
The river is going to be reduced in volume, both water and deposits, when the generators of the new Karahnjukar hydroelectric power station start revolving. The deposits will remain behind the gigantic dam in the river’s canyons and the mainstay of the water will be diverted to river Lagarfljot. Farmers in the delta area fear great changes, even considerable rise in groundwater levels, which might flood some properties and force them to leave their farms, which have been their families livelyhood during the centuries.