Anchor ice

Ground ice is forming on the base of running water ice. It grows from the river bed from into the water and sometimes bizarre forms underwater sculptures.

Formation

Grundeis only occurs with persistent severe frost periods and certain waters. It forms when the ground freezes deep in permanent frost and then in the river bed temperatures below 0 ° C can be achieved. While at first standing water cools the surface and forms there the first ice, a stable mixture of water takes place at flowing and the ice forms first on where the water is at its calmest, ie at the base and on the banks. However, in 2012 Steinachtal ( LK Kulmbach ) could be observed that the Grundeisbildung ultimately only a small connection to the stream bed needed, only to emerge " bulbous " in the flow- rich waters ( millrace ).

A further prerequisite for the formation of ground ice that no connection between the waters and the groundwater that is, that seeps only a little water or groundwater flows through the sole in the waters, because ground water penetrates from deeper soil and rock layers, thus is warmer than 0 ° C, thus preventing the freezing of the river bed.

Hazards

Ice has a lower density than liquid water. The ground ice has so buoyant. With increasing volume it can break loose and rise from the ground. Then it forms, mostly mud and gravel carrying with them, drift ice. The increased amount of ice suddenly turn can lead to ice jams.

Since Grundeis reduces the depth of the river, this may in shipping cause problems, as may the fairway is too shallow. In addition, due to the reduced river cross section even at normal water levels, the water overflow their banks and cause extensive flooding. This occurred, for example, decades ago Hachinger Bach.

Documents

• Ice
• Glaciation
• Erosion