The Hydrogeology of Karst

Hydrogeological map of Serbia

Well permeable rocks:
    1 - Alluvium,
    2 - Limestones;
Partially permeable rocks:
    3 - Upper Neogene lake sediments;
Poorly permeable rocks:
    4 - Lower Neogene sediments;
Mostly impermeable rocks:
    5 - Serpentinites, igneous and metamorphic rocks,
    6 - Karst springs,
    7 - Direction of groundwater movement.

Conclusion

    In their geological composition and their geomorphological and hydrogeological characteristics, karst terrains in general differ greatly from other types of aquifers. Karst as an aquifer demands special study of geological and other factors significant for development of the karst process itself. For example, it is known that conditions of development of the given process depend in considerable measure on the chemical composition (percentage of CaCO3), textural characteristics (manner of manifestation), and structural relations of limestones and older and younger impermeable rocks and fault structures within the limestone mass. The karst process is mainly predisposed to fault structures, along which larger channels and caverns for the most part develop.
    The sculpting of underground karst landforms (including caves and pits) unquestionably is dictated by the position of fault structures, inclination of the impermeable floor, and the spatial relationship of limestones and impermeable barriers. These geological elements - especially well-expressed tectonic structures (anticlines and monoclines) with an impermeable core or impermeable floor - and nearby barriers dictate the allocation of underground waters and their evacuation. For all of these reasons, the goal of discussing hydrogeological conditions of karst on the territory of Serbia is to gain a better understanding of the genesis of caves as especially interesting phenomena of this specific geological formation.
    It is noticeable that the density of caves on the territory of Serbia is not proportional to area of the karst mass itself. The very unequal density of caves is primarily a consequence of differences in the lithological column, tectonic relations, and hydrogeological conditions of different karst regions. For example, the slight depth to the impermeable floor and its favorable inclination, significant tectonic alterations to rocks, and favorable position of the barrier and drainage bases have led to an exceptional abundance of caves in limestone masses of the northern half of Eastern Serbia. An example that nicely illustrates this is the Kucaj-Beljanica Massif, which by all means can be counted as one of the most interesting hydrogeological and speleological regions of the karst of Serbia (Stevanovic Z., 1991).