IJssel

IJssel in Deventer

Location of the IJssel

The IJssel [ ɛi̯səl ] ( German also written IJssel or Issel called; IJ is in Dutch ligature ) is a branching off from the Rhine big river in the Netherlands. To distinguish them from the Hollandse IJssel it is called sometimes Geldersche ( Geldern or Geldernsche ) IJssel. Once it was only the lower reaches of the Issel ( Old IJssel ), whose source lies in the southwestern Munster country.

Diversion and History

South-east of Arnhem, nearly 13 river miles below the German Rhine section to the already there from the main stream ( Boven Rijn, Waal ) bifurcates diverted Pannerdensche channel in the left (west ) flowing at least 90 meters wide Nederrijn and at least 70 meters wide IJssel, which immediately turns sharply to the east.

The IJssel river takes after 19 kilometers at Doesburg as the first major tributary of the right (east) on coming Issel, their former upper reaches, which is referred to in the Netherlands as Oude IJssel. All other major tributaries also flow from the right as in the Zutphen Berkel and at Deventer Schipbeek. Links accompanies the river the saaleeiszeitliche Moränenhügelland the Veluwe with up to 90 meter high forested slopes. It is followed by track, the border between the provinces of Gelderland and Overijssel. Shortly before Zwolle, the IJssel turns to the northwest and then flows near Kampen in the Ketelmeer, a bay of the largest freshwater lake in the Netherlands, the IJsselmeer. In Zwolle branches to the right of the Zwolle - IJsselkanaal from the Zwarte Water. Also in the Ketelmeer opens the springing in the Munsterland Vecht, who carries on its behalf by the confluence of the Zwarte Water. The actual mouth of the IJsselwassers in the open sea is carried out by the outlet locks of Den Oever ( Stevinsluizen ) and Kornwerderzand ( Lorentz Luizen ).

Genesis

The Issel is separated only by insular ridge of the Rhine valley. In several places, the watershed is located on the oldest line of the Rhine dikes. Old river sediments show that before the construction of the Rhine dikes between Rees, Isselburg and Anholt and also in Zevenaar Rhine flood again and again to Issel ( Old IJssel ) transgressed.

According to popular opinion, the top section of the river has developed until after Doesburg from the fossa Drusiana, the lake of the Roman fleet the way to the former, Flevum mentioned (now IJsselmeer ) and then shortened in the German Bight. Intensive research into the history of the Rhine delta in the geoscience faculty of the University of Utrecht, cast doubt on this view because, although elsewhere in the Netherlands remains of Roman canals were found, but not at the IJssel between Westervoort and Doesburg (and not in the space also considered drawn Hollandse Vecht ).

The sediment research regarding past IJsselverläufe is still in progress. Among other things, the possibility is considered that the Oude IJssel is once flowed into the Rhine. The river bed between Westervoort and Doesburg would then at least partly of natural origin, even if at first flows through in the opposite direction - a not unusual in the Rhine -Meuse delta events.

Water engineering development

During the 17th century, the Waal developed increasingly the dominant estuary with eventually more than 90 % of the water flow of the Rhine, so that on the Lower Rhine and IJssel summer shipping could come to a standstill. To counteract this, first and above all for reasons of defense against France, 1701-1707 Pannerdensche the canal was built, with the accompanied an initially uncontrolled increase of runoff in the Lower Rhine and IJssel. In an agreement between the Kingdom of Prussia ( with a Cleves exclave on the canal Pannerden 's ) and the Dutch Republic of the Seven United Provinces of 1771 to secure a runoff proportional representation was finally agreed after the Nederrijn 2/9 and the IJssel 1/9 of the amount of water the should pay the Rhine; which are on average about 250 m³ / s One of the seven provinces was named after the river IJssel: Overijssel was until 1528 a part of the diocese of Utrecht, from which it over de IJssel - lay beyond the Issel. .

With the completion of the final dike Zuiderzee Works in 1932 as part of the IJssel resulted not directly into the sea; their catchment area was part of a larger inland river system around the IJsselmeer, which reaches over the Afsluitdike the North Sea. Its main river is the river IJssel, which, reinforced by tributaries, near Kampen at the transition into the IJsselmeer the year led ( to about 1971) well 280 cubic meters of water per second.

The construction of the Delta Works, the weir at Driel 1971 completed on the Lower Rhine, the amount of water the IJssel now so regulated as a function of the water flow of the Rhine, they s ( around 40 %) results in an average of about 100 m³ / more water than previously. If the Rhine / s leads below 1400 cubic meters, the Lower Rhine remains only a minimum flow of 25 m³ / s, otherwise comes the flow of Pannerden 's channel of the river IJssel benefit. At higher flow rates to the average water flow of the Rhine (2300 m³ / s ) of the feed stream to the IJssel is kept stable at 285 m³ / s, and the Lower Rhine receives the rest In the lock is fully open, and the Outflow is uncontrolled, with about drain 57% over the Lower Rhine and 43 % over the IJssel.

Hydrological aspects

The IJssel differs from the other arms of the Rhine delta in that (even with future natural or man- run changes ) it can have no contact with the other mouth arms after the branch, since it is separated from them by the high Veluwe. Your branch has therefore been the character of a bifurcation. Nevertheless, it is counted to the Rhine river basin. The river basin shown in most sources is often lost on the Rhine (often blurry ) watersheds and also applies for administrative reasons, the catchment areas of neighboring coastal waters with a.

The water supply of the river IJssel is since 1971 at its beginning about 350 m³ / s, when it enters the IJsselmeer 450 m³ / s where the sluices at Den Oever accounts for about 380 m³ / s and at the mouth of the open sea about 250 m³ / s and on the Kornwerderzand at around 200 m³ / s