Karst spring
A karst spring is a spring that is part of a karst system. This includes underground drainage a larger area, which means that karst springs often have a very large bed. Because of their often cone-or boiler-type form such water outlet points are also referred to as the source pot, which is reflected in names such waters Aachtopf ( origin of Radolfzell Aach ) or blue pot ( source of the blue to blue Beuren ). Other karst springs rise cliffs, such as the Source de l' Orbe or Rinquelle.
Karst springs are usually the end of a cave system where a cave river reaches the earth's surface. Thus, it is often possible at the karst spring to enter this cave system and explore.
As the swelling pot or Ain water outlet points are referred to in North Africa, which pass through the effect of an artesian basin to days and are in the arid areas of particular importance. You can directly promote outflowing water or escape under evaporitic salt crusts. Well-known example can be found in the oases of the Tunisian landscape Djerid and the entire environment of the Chott el Jerid and depression Chott el Gharsa. There are water -bearing strata, usually sand or sandstone that occur as aquifers in function.
Hydrological features
The most important feature of karst springs follows from the fact that in areas with superficial carbonate rock this is transformed by the carbonic acid content of rainwater into soluble calcium bicarbonate over time. This gives rise to caves and underground streams, so that the water comes out after a few days to a source. Unlike groundwater is no cleaning and it comes to a very different packing: storms, snow melt and seasonal variations in rainfall at the source noticeable. A special position is occupied by the Aachquelle, because their water comes not from rain but from seepage in the Danube about 12 km away.
Many karst springs dry up in low-rainfall periods, then one speaks of intermittent sources. Still others are most of the year, dry and pour only after heavy rainfall. Sources that pour only in wet years are often called hunger well, what does it matter that the vernacular sees a connection between the spill source and a poor yield in a rainy year. It is, however, rather a culturally conditioned superstition. Scientific studies on various Hungerbrunnen could not demonstrate such a connection. An example is the hunger Fountain at Heldenfingen in barley tablets.
The quality of karst spring water is unsuitable for drinking water supply due to lack of cleaning and high hardness. In addition, uneven feeding even low bed faces a uniform consumption, in summer an increased demand. For these reasons, karst springs are now hardly used for drinking water supply.
Karst spring of Kamenscica in Gorski Kotar in Croatia
Creux- Genat in Switzerland
Vrelo Bune in Bosnia and Herzegovina
Witches fountain of Tuhala (Estonian Tuhala nõiakaev ) Tuhala, Estonia
Examples
Some selected examples of karst springs:
- Blue pot ( Germany )
- Foce del Timavo (Italy )
- Izvor Omble (Croatia )
- Pießling origin ( Austria )
- Source du Doubs (France)
- Seven sources ( Switzerland )
- Syri i Kalter (Albania)
- Vrelo Bune (Bosnia and Herzegovina)