Case Studies from the Dinaric Karst of Slovenia

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the surface occurs in the south-west, wherethe surface drops from about 160 m a.s.l. tothe sea level on the distance of 300 m only.There are numerous caves, some of them areover 100 m deep, but they do not reach theunderground karst water level or the main flowof the underground Reka river that appearsin springs at sea level only about 7 km to thenorth-west.Divaški krasDivaški kras (Divača Karst) is the karstsurface above Škocjanske jame; it is sometimescalled also the Škocjanski kras. The Divaškikras is situated in the south-eastern edge ofthe Kras between ponors of the river Rekaand Divača village. It is composed chiefly ofCretaceous and Palaeogene limestones. Thesurface is levelled at altitudes between 420 and450 m a.s.l., inclined slightly north-westwardsand dissected by karst denudation. There areoutstanding karst features covering an areaof 32 km 2 , including ponors of the Reka riverand two smaller streams, 15 large collapsedolines, 64 caves, among them Škocjanskejame, Kačna jama, Divaška jama and Trhlovca,plus hundreds of dolines. The Reka river sinksin Škocjanske jame and flows into Kačnajama. Explored passages of Divaška jamaand Trhlovca are situated some 200 m abovethe underground water course and containa lot of fluvial sediments. A number of fossilcaves completely filled with sediments wereuncovered during the highway constructionin the area. A comparison of the proportionof area of smooth relief and the area coveredwith dolines and collapse dolines shows thatlevelling is a dominant geomorphologic processFig. 40: Digital elevation model of Kras plateau (DEM source: DMV 12.5 m, Geodetska uprava Republike Slovenije; figuremade by: A. Mihevc).51
in this part of the Kras (Mihevc 2001). Theproportional area of dolines is low, despite thegreat vertical gradient in karst. In comparisonwith doline surfaces, the speleologicalelements (collapse dolines, unroofed caves andcave entrances) are an important part of therelief. Even more important is the proportionof speleological elements in karstic relief ifwe compare volumes of ordinary dolines andcollapse dolines. Even though the areas ofthe dolines are only twice those of collapsedolines, the volumes of collapse dolines arefive times larger than those of collapse dolines.Ljubljanica River SystemThe karst area along underground Ljubljanicariver is important from a historicalpoint of view because karst hydrology studiesbegun here in the 16 th century and numerouskarst features were first described hereand are the reference features for the similarfeatures elsewhere. Important features of theLjubljanica karst are: poljes (Cerkniško polje,Planinsko polje); high karst plateaus (Hrušicaplateau), dolines, collapse dolines, cave systems(Postojnska jama – Planinska jama cavesystem, Križna jama, Rakov Škocjan) and karsthydrology (sinking rivers, ponors, springs,floods; Fig. 41).Ljubljanica River collects the water fromsouthwest part of the Dinaric karst in Sloveniaand belongs as right Sava affluent to Danubepart of Black Sea water basin. The real watershedis placed somewhere in the underground,and the waters from karst plateauare flowing to all sides. The Ljubljanica waterbasin is about 1,100-1,200 km 2 . The mean annualprecipitation in the basin is 1,300-3,000mm, during 100 to 150 rainy days. The one-daymaximal amount to 100 mm, in extreme caseseven 300 mm.Most of the river basin is formed on Mesozoicrocks, mostly limestone. On these rocksthe precipitation infiltrates directly into thekarst and there are no surface rivers. Triassicdolomite is important, allowing some surfaceflow, forming bottoms of some karst poljes orforming hydrologic barriers.The highest parts of the basin are highkarst plateaus Hrušica, Javorniki and Snežnikand Racna gora. On the poljes among them,surface rivers appear only, but they have differentnames: Trbuhovica, Obrh, Stržen, Rak,Pivka, Unica and finally after the springs at Vrhnikathe name Ljubljanica. The highest lying isthe karst polje near Prezid (770 m), followedby Babno polje (750 m), Loško polje (580 m),Cerkniško polje (550 m), Rakov Škocjan andUnško polje (520 m), Planinsko polje (450m),Logaško polje (470 m) and finally LjubljanskoBarje (300 m), where the Ljubljanica springsare at 300 m a.s.l. There are several largesprings are dispersed along the edge of theLjubljana Moor, which is connected with thegradual tectonic subsidence of the area. Meanannual discharge of the Ljubljanica River at thesprings is 38.6 m 3 .There are about 1,540 caves, accessiblefragments of underground drainage systemknown in the catchment area of the Ljubljanica.Almost fifty kilometres of cave passages areknown to exist along significant undergroundwatercourses. The average length of the caveis 48 m and the depth 18 m. However, thelargest caves are the ponor or spring caves;in them we can follow the 71 km of passagesof the main rivers, tributaries of Ljubljanica.Larger caves found in this area include the Karlovice,Zelške jame, Tkalca jama, and Planinacaves. In Planina Cave these waters are joinedby the Pivka River from Postojna Cave. From52
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 and 28: absent. Downstreamparts of the cany
Page 29 and 30: GeomorphologyAndrej MihevcIn folk l
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: KrasThe Kras is a distinct plateau,
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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