Case Studies from the Dinaric Karst of Slovenia

the Planinsko polje, the underground LjubljanicaRiver flows through Logarček, the Najdenajama cave, and the Vetrovna jama cave. Thesecaves provide a habitat for the Proteus anguinussalamander (the “human fish”) and othersubterranean water animals.Logaško polje (Logatec polje)The Logaško polje developed on the contactof dolomite and limestone between 470-480 m a.s.l. A number of small streams flowonto in it, the largest being the Logaščica,which collects run-off from an area of 19 km 2 .The mean flow is 0.3 m 3 /s. Short lasting floodsoccur at the swallow-holes Jačka on theLogaško polje when the flow exceeds 30 m 3 /s.The bottom of the polje is covered by a thinsediment cover of sinking streams that flowfrom Triassic dolomites and marls and Palaeozoicrocks. Sediments deposited on levelledsurface reveal the catchment area of the depositingstreams. At the present the washingof sediments into the ponors is main processfrom which subsidence connected with pipingof sediments appears, and there is also someerosion of the river banks.Planinsko polje (Planina polje)Planina polje is an overflow polje, of rectangularshape, 6 km long, 2 km wide, with twonarrow pocket valleys on SW part, 50 m deep,with a 16 km 2 flat surface at height of 450 m.Its wider surrounding area is built by Upper Triassicdolomite, Jurassic and Cretaceous limestone.The development of the closed karstdepression is result of accelerated corrosion,controlled by geological structures.It presents the most important water confluencein the river basin of Ljubljanica. A tectonicallycrushed and almost impermeableFig. 41: Digital elevation model of Planinsko polje (Planina polje) with the most important springs, ponors and cave passages(DEM source: DMV 12.5 m, Geodetska uprava Republike Slovenije; figure made by: A. Mihevc).53