Pilot project karst hydrogeology Hartelsgraben 2006-2008

Knowledge of the (mostly underground) drainage of a karst area is the key to understanding the formation and development of caves in this region. While in many important karst areas of the Northern Limestone Alps a quite plausible model of drainage can be created today on the basis of very extensive and elaborate investigations (with mostly water management background), this is not yet possible for the Gesäuse. Since the waters of the Gesäuseberge are not used nationally, but only regionally and locally, such comprehensive investigations have so far not been carried out for cost reasons. In addition, the geological-morphological findings already show a special feature of karst watering: The powerful dolomite base practically acts like a sponge, so it has a tremendous retention capacity and releases the water not in some large karst springs, but in a myriad of small springs. Only in the event of extreme precipitation events or snow melting are fairly high-lying spring outlets active at the dolomite/lime line and above, which then drain temporarily and above ground in the dolomite area and lead to the known erosive terrain forms in the dolomite karst. In the area of the Hartelsgraben, however, the dolomite is already so deep that the entire trench only cuts through the Dachstein limestone (Figure 3) and the Hartelsgraben has a special hydrological position at least for a part of the southern Gesäuseberge.