The IJssel has not always run through the IJssel valley in the past. Around the beginning of the era another river, the Berkel, flowed in the southern part of the IJssel valley. This flowed in the opposite direction, namely to the south. The Oude IJssel joined it at Doesburg and together they flowed into the Rhine at Arnhem . In the northern part of the IJssel valley, a number of streams flowed in a northerly direction, starting with the current Schipbeek (near Deventer). The watershed between the two systems was at the level of what is now called the Voorster Clay, near the place Voorst. The IJssel valley itself is a remnant of the old ice ages and a former bed of the primal Rhine.
The IJssel eventually, presumably at the beginning of the 4th century, was created as a breakthrough between the two brook systems because the Berkel estuary, between Arnhem and Doesburg and later between Arnhem and Zutphen, started to contain more and more water at high water levels in the Rhine . To defend their northern border (‘limes’) the Romans pushed at the junction of the Waaland the Neder-Rijn more water to the Neder-Rijn, causing the flood of water to break through the watershed and the river dunes and make its way north. It then took several centuries before a clear channel was formed that was also navigable. The course of the IJssel has subsequently shifted regularly, also due to the interference of humans through canalisation, dykes and paving with groynes and stone banks. The last canalisation dates from 1959, but very recently a bypass to the Drontermeer was dug south of Kampen. Currently Rijkswaterstaat and the water on new secondary channels to dig the water at very high water to drain faster into the IJsselmeer.
Kampen, a city along the Ijssel