The Rhine is fed by both rain water and melting ice from glaciers. It originates in Switzerland and runs through Germany and the Netherlands before exiting to the North Sea.
In total, the Rhine is 1320 kilometres long. The output is on average 69 billion cubic metres, - as much as a 1.7 metre high pool of water covering the whole of the Netherlands. Parts of the Rhine have been canalised in order to improve the navigatability of the river.
Moreover, it ensures the water supply of the north of the Netherlands and in particular the Ijssel Lake. One of the characteristics of a rain river, is that the variation between the highest and lowest output is larger than that of a glacier river.
When it rains heavilly, the output is high and when it does not rain the output is greatly reduced. The average glacier river however maintains a much more gradual drainage due to the continuous melting process.
The average output of the river Maas is ‘only’ 8 billion cubic metres, which is the same as a 20 cm layer of water covering the Netherlands. In comparison: the annual precipitation in the Netherlands is 75 cm.
Only the mouth of the river Scheldt lies within the Dutch border. The river is quintessential for the port of Antwerp, in Belgium.
When designing the Delta plan after the flood of 1953, the primary reason not the dam the Westerschelde was due to the accessibility of the port of Antwerp.
Other smaller rivers that originate abroad but flow through the Netherlands are of no significance when compared with the rivers Rhine, Maas and Scheldt.
Dutch lakes were often created through the sea forcing holes in the dunes or through old rivers not getting any fresh water supplies.
The Ijssel Lake on the other hand was created when the Zuyder Sea was dammed, and the Lake of Veere was created when part of the Oosterschelde was dammed.
Humans have clearly left their marks on the Dutch landscape. Other areas are nowadays called ‘pools’ when they have flooded after being dug off, due to the presence of peat. A large number of lakes and pools have been reclaimed during the last centuries.