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Akarst spring orkarstic spring is aspring (exsurgence, outflow ofgroundwater) that is part of akarst hydrological system.[2]
Because of their often conical or inverted bowl shape, karst springs are also known in German-speaking lands as aTopf ("pot") which is reflected in names such asAachtopf (the source of theRadolfzeller Aach) orBlautopf (the source of theBlau river inBlaubeuren).
Karst springs often have a very highyield ordischarge rate, because they are often fed by underground drainage from a largecatchment basin. Because the springs are usually the terminus of a cave drainage system at the place where a river cave reaches the Earth's surface, it is often possible to enter the caves from karst springs for exploration.
Large karst springs are located in many parts of the world; the largest ones are believed to be inPapua New Guinea, with others located inMediterranean countries such asBosnia and Herzegovina,Croatia,Turkey,Slovenia, andItaly.[3]
Anestavelle orinversac is a ground orifice which, depending on weather conditions and season, can serve either as a sink or as a source of fresh water. It is a type ofsinkhole.[4]
AVauclusian spring is a spring that originates from a shaft or a cave system, with the water surging upwards under relatively high pressure. It is named after theFontaine de Vaucluse in southern France.[4]
Submarine karst springs, also known asvruljas, occur worldwide, and are most numerous in shallow waters of theMediterranean Sea.[4] They can be considered to be karst springs which have become submerged byrising sea levels.
Forintermittent orrhythmic springs see below. They are part of another type of classification, which differentiates betweenperennial (with continuous flow),rhythmic, andtemporary springs.[clarification needed]
A main feature of karst springs is that water is rapidly transported by caverns, so that there is minimal filtering of the water and little separation of different sediments. Groundwater emerges at the spring within a few days from precipitation. Storms, snowmelt, and general seasonal changes in rainfall have a very noticeable and rapid effect on karst springs.[5]
Many karst springs dry up during the driest part of the year, and are thus known asintermittent springs.[dubious –discuss] Still others are dry most of the year round and only flow after heavy rain. Sources that only flow during wet years are often known in German asHungerbrunnen ("hunger springs"), since folklore claimed a connection between the flow rate of a spring and poor crop yield in a wet year. This appears to be more of a culturally-relatedsuperstition, as scientific studies on variousHungerbrunnen have not confirmed such a relationship. An example is theHungerbrunnen in the parish of Heuchlingen nearGerstetten.[6]
The properties of karst springs make them unsuitable for the supply ofdrinking water. Their uneven flow rate does not support a steady rate of consumption, especially in summer when there is lower discharge but higher demand. In addition, poor filtering and highhardness mean that the water quality is poor.[7]
The FrenchRealist painterGustave Courbet (1819–1877) painted a number of karst springs among many landscapes he depicted in theJura region of eastern France.[8]
