|Near Palfau. At the end of the Wasserlochklamm.
|Karst spring Intermittent Spring
Average Yield: 2,000 l/s.
Maximum Yield: 6,000 l/s.
Minimum Yield: 1,250 l/s.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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|cave diver Robert Seebacher reaches depth of 42 m.
|Bat-Diver-Team of Robert Kriz reaches supposed lowest point of the siphon at 71 m.
The Palfauer Wasserloch is not only a karst spring with an enormous yield, it is also the strangest spring of Austria. Located in the middle of a cliff face it is reached through a steep gorge after an ascent of 350 m along numerous rapids and waterfalls. The cave behind the spring is water filled but big enough for diving. During various diving attempts by the cave diver group Bat-Diver-Team of Robert Kriz reached a dept of 71 m. They suppose it is the lowest point of a sink and the cave will go up afterwards. The hope is always to reach an air filled part of the cave. However, it is the deepest cave sink in Austria and also the largest water filled cave in Austria.
The strange part of the cave is that the yield goes up and down without obvious reason. Unlike normal karst springs it is normally not connected to heavy rains or snow melt. The obvious explanation is that the cave has no side branches and is filled by cave river. A sink behind the current sink is filled with water, and when it is filled it overflows. The outflow produces low pressure which sucks the water out of the chamber on the other side.
This principle is used to empty a tank with a rubber tube. If the tube is full of water, one end in the tank and one end outside, the water will flow through the tube by gravity until the level inside reaches the level of the outer end of the tube.