Can a river disappear without a trace?

On the trail of the Danube
(Backblip)

It is not a spectacular blip, but it is an unique place.
Here, the river Danube dissapears on almost 155 days every year without a trace. If you are interested in this worldwide unique phenomenon, please have a look at the extra. I added an info panel in the extra :-D
Unfortunately there was still some water in the riverbed, when we visited this place. But it was almost dry.
We also visited the place, where all the water appears again, 12 km away, the well of the river Aach. It is europas biggest well- and it is unbelivable!