IJssel

The river IJssel, sometimes called Gelderse IJssel to avoid confusion with the Hollandse IJssel, is the branch of the Rhine in the Dutch provinces of Gelderland and Overijssel. The Romans knew the river as Isala. The IJssel flows from Westervoort, east of the city of Arnhem, until it discharges into the IJsselmeer . The River IJssel is one of the three major distributary branches into which the Rhine divides shortly after crossing the German-Dutch border.The name includes the digraph ij, which behaves like a single letter in Dutch orthography - this explains why both letters appear capitalized .HistoryThe name IJssel, is thought to derive from a Proto-Indo-European root *eis- "to move quickly" . In the Middle Ages, the Zuiderzee had not yet formed, and in its place there was an inland lake known as Vlies, and the IJssel flowed through the surrounding lakelands. However, since the formation of the Zuiderzee and obstruction from the Afsluitdijk, the IJssel no longer flows into its estuary, the Vlie, now restricted in meaning and referring only to the strait separating the islands of Vlieland and Terschelling. It is hypothesised that the now-poldered tidal inlets near Medemblik and the IJ once were branches of river IJssel.