Ponor

A Ponor (from the South Slavic ) - also known as swallow hole, sinkhole ( English), Schwalgloch ( the Westphalian ), sinkhole, stream Schwinde or katavothra ( Modern Greek: καταβόθρα ) known - is an opening in the ground surface, at a flowing or standing water flows and continues to flow underground. The Ponor is a typical, occurring in many regions of the world karst phenomenon, and therefore frequently occurs in regions where the subsoil consists of limestone.

Depending on the ratio between the size of the opening and the volume of the subsequent underground cave system (flow capacity) and the inflow amount of the corresponding body of water, a distinction is made in the German language area shrinkage and roll.

Schwinde ( one also says River sinkhole, stream or water sinkhole sinkhole ) here refers to those cases in which the amount of inflow is less than the flow capacity of the cave system. This manifests itself in the fact that a stream, simply disappears in a corresponding opening in the truest sense of the word.

Roll on the other hand refers to those cases in which the inflow is greater than the flow capacity of the cave system. This is the opening through which the water flows into the underground cavity, below the water surface. However, if the amount of water seasonal or climate-induced decreases to the extent that the amount of inflow, the flow capacity of the cave system below, that the waters be completely swallowed, ie, a roll if appropriate, could turn into a sinkhole. Increases the amount of inflow back to the extent that it exceeds the flow capacity, a roll out of the sinkhole again.

Other forms of acceptance of above-ground drainage are the area percolation of rainfall in all karst areas or in these infiltration routes through gravel surfaces in a cave, a stream or river. Examples are the Donauversickerung, the seepage of Lone, the Wutach, the Alme, the sour, the Pegnitz, three tributaries of Wehra on the Upper Rhine, the Ill, the Schwarza, the infiltration of Eichener lake and seepage of the Lesse in the cave of Han-sur -Lesse in Belgium.

By sink holes, water can also be discharged beyond a watershed. To determine flow paths and flow rates, labeling experiments may be undertaken with tracers.