Case Studies from the Dinaric Karst of Slovenia

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Kupa/Kolpa, Morača). The continental mountainousDinaric karst was for many hydrologicalphenomena (polje flooding, complexunderground water flow between poljes, bigponors, springs and estavellas, hydro technicalworks) the first area to be studied or extensivelyused. In recent years, big karst springs arerecognized also due to their surprisingly deepsumps (Fig. 17 on page 25) of Una (-205 m), Divjejezero (-160 m), Sinac (-155 m), Kupa/Kolpa(-154 m; Knab, 2008). Nowadays, at least14 sumps are deeper than -100 m. An evenmore exceptional case is Crvenojezero (Red lake; Fig. 21)with depth -281 m (Knab 2008)and without clear genesis.The low northeastern andhigh southeastern inland karstlies northeast of continentalmountainous karst. The northeasternpart is characterized bylow elevation hills and plains,where both surface and subsurfacedrainage occur. A greatportion of the relief is occupiedby a karst-leveled surface(e.g., Bela Krajina, the leveledsurface between the riversKupa/Kolpa and Una), in whichcanyons are deepened (SloveneKrka, Kupa/Kolpa, Dobra,Mrežnica, Una). The elevationof the rivers is similar and theelevation of subsurface waterbetween them is slightly higher;this prevents from undergroundcirculation betweenrivers. Regarding these characteristics,the low northeasterninland karst is similar to Sjevernodalmatinskazaravan andRavni kotari along the Adriaticcoast. In the northeastern direction,the elevation of inlandkarst decreases until it sinksbeneath young sediments ofthe Panonian basin. Toward the southeast, thesoutheastern inland karst becomes more andmore hilly and karst valleys become deeperdue to a higher portion of Triassic dolomiteand higher elevation. Rivers (e.g., the Tara andPliva) flow in canyons over 1,000 m deep betweendissected karst plateaus with combinedsurface and underground drainage flow. Bigkarst springs are absent, but several of themcan initiate larger rivers (e.g., the Neretva, Vrbas,Miljacka, Željeznica, Usora; Papeš & Srdić1969).Fig. 21: Crveno jezero (Red lake; photo: A. Mihevc).29
GeomorphologyAndrej MihevcIn folk language, “karst” meant “barrenstony land.” This term often occurred in localtoponyms and could denote an entire landscape.Today, the word “karst” means a landscapewith specific relief, water, and undergroundfeatures that formed in long geologicalperiods on water-soluble rock, mostly limestoneand dolomite (Gams 1973; Kranjc 1998).Relief on impermeable non-karst rock isprimarily sculpted by water that runs on thesurface in river networks. Rivers sculpt fluvialvalleys that dissect the surface into valleys,slopes, and ridges. The valleys are deepenedby the mechanical erosion of rivers, which isgreater where the inclination is steeper andthere is more water. The slopes above valleysare shaped by sheet erosion or denudation.As a rule, closed depressions do not form inthis relief, but if they do, they are immediatelyfilled by water or sediment.On karst, however, relief is formed by waterthat chemically dissolves the limestoneand carries the solution away. Gravel thereforedoes not form on the surface and very littleinsoluble debris remains on the limestone.Gravel and insoluble debris could fill nascentdepressions in the relief, cover the bedrock,and be the basis for the formation of soil. Sincethis is not the case, the karst surface is rockyand hollowed.Pure water can dissolve only a little limestoneor its main component, the mineral calcite.Solubility increases when CO 2from theair or soil is dissolved in the water resultingin weak carbonic acid. Dissolving or corrosionis further accelerated by acids produced byplants or the decomposition of organic matterin the soil.The dissolution of karst rock is strongest onthe surface or a few meters below the surface,but water remains aggressive for a long timeand can form caves underground. Sheet erosionand the lowering of the surface results inkarst denudation. Various methods have determinedthat denudation has amounted tobetween twenty and fifty meters in a millionyears in Slovenia’s karst regions (Gams 1974).This also means that surface denudation hasalready reached individual caves and removedtheir ceilings to create roofless caves (Mihevc2007)Rivers flow onto karst areas and form undergroundstreams. Because they carry largeamounts of water and sediment from impermeableneighbouring areas, they are capableof dissolving a considerable amount of limestone,but their effect is limited only to the vicinityof the watercourse (Gams 1962; Mihevc2001).Karst rock featuresSome dolomites and most of the limestoneare mechanically very resistant types ofrock, but they are all subjected to dissolution.Precipitations start to dissolve them as soonas they get into contact with the karst rocks.Intensity of the corrosion depends on propertiesof the rock, aggressively of the water andthe way in which water flows on the surface ofthe rock. Small corrosion features that form onthe rock make its surface uneven and rough orform different shapes.Karen is common term used for dissolutionfeatures on exposed soluble rock surfaces.(Gines 2009). Two basic processes controltheir formation, the dissolution by thin water30
Page 2 and 3: Andrej Mihevc, Mitja Prelovšek, Na
Page 4 and 5: ContentsGeographical Position and G
Page 7 and 8: Fig. 2: Coastal part of Dinaric kar
Page 9 and 10: ogy started. In 1531 a lawyer from
Page 11 and 12: include numerous data and general o
Page 13 and 14: GeologyNadja Zupan HajnaThe Dinaric
Page 15 and 16: ceous. The final disintegration of
Page 17 and 18: Fig. 11: Locations of Jelar Breccia
Page 19 and 20: ClimateMitja PrelovšekThe Dinaric
Page 21 and 22: 311 mm/a; Zaninović 2008) and incr
Page 23 and 24: 24Fig. 16: Spatial distribution of
Page 25 and 26: ocks (such as Eocene flysch, Lower
Page 27: absent. Downstreamparts of the cany
Page 31 and 32: long. They are smoother especially
Page 33 and 34: is now depositing. Best known are t
Page 35 and 36: Structural poljes are dominated by
Page 37 and 38: Fig. 28: Typical dolines of Dinaric
Page 39 and 40: the disintegrated collapsed rock at
Page 41 and 42: on Northern Velebit, where three ca
Page 43 and 44: Land UseNadja Zupan Hajna, Andrej M
Page 45 and 46: for ‘bare limestone desert’ -th
Page 47 and 48: Fig. 38: Grančarevo dam in the upp
Page 49 and 50: KrasThe Kras is a distinct plateau,
Page 51 and 52: in this part of the Kras (Mihevc 20
Page 53 and 54: dolomite barrier along the Idrija w
Page 55 and 56: of Dolenjska (Gams, 1974; Kranjc, 1
Page 57 and 58: Fig. 44: Blind valleys of Matarsko
Page 59 and 60: ly several dozen meters deep. Shaft
Page 61 and 62: smaller than the higher ones. The r
Page 63 and 64: tion in the Divaški kras (Mihevc 1
Page 65 and 66: Use of Karst and its ProtectionThe
Page 67 and 68: Gams, I., Vrišer, I. (Eds.), 1998:
Page 69 and 70: lems.- Dela 38, Raziskovalni center

Case Studies from the Dinaric Karst of Slovenia

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