ICPR – International Commission for the Protection of the Rhine

Water cycle

Sooner or later all precipitation in the Rhine area, all raindrops, hailstones and snowflakes reach the Rhine and eventually the North Sea. In the North Sea, part of the water evaporates to form clouds and re-precipitates. This concludes the water cycle.

The speed at which the water concludes the cycle depends on how long it is being retained on its way to the North Sea. Part of the rain or melting water infiltrates the soil and flows towards the sea underground as groundwater. Plants too withhold great amounts of water, as do glaciers in the form of ice and lakes.

Thus, the runoff of the Rhine and its gauge vary according to the seasons – all depending on precipitation, water uptake and the melting of glaciers and snow. This means that low water levels and floods are part of the natural water cycle of the Rhine.