Case Studies from the Dinaric Karst of Slovenia

HydrologyMitja PrelovšekThe present day hydrological characteristicsof the Dinaric karst are the result of itscomplex geologic structures and a long andintensive geomorphic evolution. In addition toits varied geology and geomorphology, the hydrologyof the Dinaric karst is one of its mostdistinctive and recognizable elements. The Dinarickarst is an area where hydro-geomorphicphenomena were studied for the first time inthe world in details and where some hydrogeologicalideas were born. It is a place of riversthat sink and reappear several times, a placeof abundant ponors and springs connected byhydrologically active caves, a place where thetypically impressive features of contact karstoccur, and a place where the complex hydrologicalsystems between poljes were modifiedFig. 17: Glavaš is over 115 m deep spring of river Cetina (photo: A. Mihevc).and used for production of hydroelectricity afterthe 2 nd World War.The Dinaric karst is a region that extendsover Dinarsko gorovje (the Dinaric mountains)and comprises both permeable (karstic) andnon-permeable rocks. Due to this mixed geology,two major types of drainage have developed:non-karstic surface drainage and theprevailing subsurface drainage typically associatedwith karst. Even pure and fractured limestonecan support superficial flow if regionalfactors (e.g., hydrological barriers, hydraulicgradients that are too low) do not favor undergroundflow (i.e., as occurs at karst poljes). Nevertheless,fully developed underground drainageis characteristic for areas with very purelimestones (those with less than 1 % of impuritiesare abundant inDinaric karst), withsprings at relativelylow elevation andwithout importantfault zones. At suchplaces, subverticaldrainage whichturns subhorizontalat water leveland drains towardsprings nearby. Verygood examples ofsuch drainage areat the mountainsVelebit, Biokovoand also at somelowland plateaus(e.g. plateau Kras).Aside fromsuperficial drainageon impervious25