Case Studies from the Dinaric Karst of Slovenia

absent. Downstreamparts of the canyonsare submerged dueto the tufa dams andthe rise in sea level atthe beginning of Holocene.In Istria, thecanyons of the riversMirna and Raša areshallower but alsopartly submergedat the downstreamends.The most characteristichydro-geomorphicphenomenaof the continentalmountainous karstare high plateaus andkarst poljes. The main Fig. 20: Spring of river Buna (photo: M. Prelovšek).ridge of continentalmountainous karst lies above 612 m a.s.l. Thewidth continental mountainous karst rangesbetween 30 to 110 km (Šarin 1984). The transitionfrom the southwestern coastal Adriatickarst can be double this width in places. Insome parts of Adriatic coast, Dinarsko gorovjerise from the coast very steeply without leveledBesides Ljubljanica springs (Q min= 4.3 m 3 /s,Q avg= 39 m 3 /s, Q max= 132 m 3 /s; Gospodarič &Habič 1976), the most efficacious springs inDinaric karst are located in this area (Fig. 16on page 24: Buna spring (Q min= 3.0 m 3 /s,Q avg= 23.7 m 3 /s, Q max= 123 m 3 /s; Fig. 20), Bunicaspring (Q min= 0.7 m 3 /s, Q avg= 20.3 m 3 /s,transition (Učka, Velebit, Biokovo, Orjen, Q max= 207 m 3 /s) and Trebišnjica springLovčen). In such areas, water is drained verticallythrough vadose zones up to 1,350 mdeep and often discharges in vruljas along theAdriatic coast. Behind Istra and Sjevernodalmatinskazaravan, the rise is more gradual. Ineastern Herzegovina, the rise in elevation goesthrough several karst overflow poljes, wherethe lowest are in southwest and the highestin northeast. Water appears and disappearshere several times, from the highest Gatačkopolje and Nevesinjsko polje (Nevesinje polje))through Cerničko (Cernica polje), Fatničko(Fatnica polje), Dabarsko (Dabar polje), Ljubijsko(Ljubinje polje) and Ljubomirsko polje(Ljubomir polje) to Popovo polje and finally tothe spring Ombla at Adriatic coast and springsalong the river Neretva (Milanović 2006).(Q min= 2 m 3 /s, Q avg= 80 m 3 /s, Q max> 800 m 3 /s;Milanović 2006; Ford & Williams 2007 afterMilanović 2000). Similar topography and hydrologicalsystems have developed in westBosnia and Herzegovina. Underground waterflow between karst poljes can be directed eitherperpendicular to the main ridge of Dinarskogorovje (this means also perpendicular tothe smaller ridges and karst poljes –e.g., westernand eastern Herzegovina, the higher partof Slovene Dolenjska) or parallel to it (part ofLjubljanica basin, NE of Velebit). Some tectonicwindows of older (Paleozoic) impervious,or less permeable, rocks enhance superficialrunoff that drains into ponors (e.g., NE of Velebit,central Bosnia), but in very rare cases riverscan flow across Dinarsko gorovje (Neretva,28