Ponor
A ponor (which, from South Slavonic ) - also known as Schluckloch , sinkhole (English), Schwalgloch (in Westphalian), Schwinde , Bachschwinde , katavothra ( modern Greek καταβόθρα ) or gully - is an opening in the surface of the terrain at which a flowing or stagnant water drains and continues underground. The ponor is a typical karst phenomenon that occurs in many regions of the world , and therefore occurs frequently in regions whose subsoil consists of limestone . Inlet holes in the sinkholes typical of karst areas are known as ponor dolines .
Depending on the ratio between the cross-sectional area of the opening or the volume of the adjoining subterranean cave system (flow capacity) on the one hand and the inflow of the corresponding body of water on the other hand, a distinction is made in the German-speaking area shrinkage and curling .
Dwindling
A shrinkage (also called river shrinkage , stream shrinkage or water shrinkage ) describes the case in which the inflow is small enough to be able to pass the opening and the adjoining cave system without the water being dammed up on the surface and at least partially normal there can drain. This is expressed in the fact that a brook simply disappears in such an opening, in the truest sense of the word .
Risle river shrinkage near La Ferrière-sur-Risle ( Département Eure )
Stream shrinkage of indulgence in the Givet mass limestone of the Brilon plateau
Stream shrinkage in the Stubai Alps . The opening to the cave system is covered here by debris
Đulin ponor, Croatia
Sway
A snake , on the other hand, describes the case in which the inflow is greater than the flow capacity of the opening or the adjoining cave system. As a result, most of the water flows normally on the surface and the corresponding cave entrance is below the surface of the water. However, the inflow amount can seasonal or climate-related drop so far that of a rolling a Schwinde is. Increases the inflow amount again over the flow capacity, is from the sinkhole again rolling .
Other forms
Other forms of decreasing surface drainage are the areal infiltration of precipitation in all karst areas or in these the infiltration routes through gravel surfaces in a cave, a stream or a river. Examples of this are the sinking of the Danube , the seepage of the Lone , the Wutach , the Alme , the Sauer , the Pegnitz , of three tributaries of the Wehra on the Upper Rhine , the Ill , the Schwarza , the seepage of the Eichener See and the seepage of the Lesse in the cave from Han-sur-Lesse in Belgium.
Water can also be discharged through ponors beyond a watershed , as in the case of the sinking of the Danube near Immendingen (the outlet water , the Radolfzeller Aach flows into Lake Constance , the Danube water reaches the Rhine in this way ). In order to determine flow paths and flow rates, marking tests with marking substances can be undertaken.
See also
literature
- Lexicon of Geosciences. Volume 4 (North to Sib). Spektrum Akademischer Verlag, Heidelberg & Berlin 2001, ISBN 3-8274-0423-1 .
- Hans Murawski, Wilhelm Meyer: Geological dictionary. 10th edition, 278 pages, Ferdinand Enke Verlag, Stuttgart 1998 ISBN 3-432-84100-0 .
