Development and Karstification of the Karst Aquifer as Discovered Between Klanec and Črni Kal

Abstract

Between Klanec and Črni Kal, on a 6.5 km route of the motorway, 67 caves opened during earthworks, road cutting and tunnel digs. The majority consisted of old caves, i.e. caves which once had water passing through. Two thirds of these caves were filled with alluvium. Research carried out in these caves augmented knowledge about the development of this part of the Karst region. A cave system extending more than 500 m, which we tried to preserve in full, opened in the Kastelec tunnel near the Brezno na Škrklovici Shaft. Underneath the road, the passages of this system are connected with concrete tubes which are accessible via a gully at the side of the road. Most of the motorway route runs over alveolinid-nummulitid limestone which is relatively resistant against karstification, accounting for the fact that in most cases only its surface and the parts close to the surface are distinctly karstified. Due to the construction of the tunnel and extensive roadcuts, the impact of the activities affecting the Karst Edge and its hinterland was significant, in several places leading to the unearthing of today’s epikarst and a part of the vadose zone, both of which are also intersected with old caves. Besides the palaeokarst, these caves provide the oldest traces of karst development in this area. The caves which were discovered during construction gave us new insights about the cavernosity of the Karst and its development.