Current utilization and hydrochemical characteristics of geothermal aquifers in the Bjelovar sub-depression

Main Article Content

Tamara Marković
Željka Sladović
Dragutin Domitrović
Igor Karlović
Ozren Larva


The Bjelovar sub-depression is situated in the north-western part of Croatia, on the southwestern margin of the Pannonian Basin System where favourable geothermal conditions exist. Thermal waters are used for recreation, balneotherapy, space heating, directly as sanitary water and electricity production. Geophysical, geological and borehole data were used to determine the types of geothermal reservoirs. In addition, several campaigns were conducted to sample geothermal waters from the Daruvar spa, Velika-1 and Krečaves locations for isotope (δ18Ο and δ2H) and physico- chemical (EC, T, pH, DO, Na+, K+, Mg2+, NH4+, Ca2+, SO42-, Cl-, Br-, F-, SiO2 and H2S) analyses to determine their hydrochemical characteristics. Two major types of geothermal reservoirs were determined: (i) ‘basement – BM’ reservoir, (ii) ‘basin fill – BF’ reservoir. The BM reservoir consists of Palaeozoic and Mesozoic sediments composed of: (i) fractured/karstified carbonate sediments and/or (ii) fractured/fissured crystalline/metamorphic rocks. The BF reservoirs are ‘Lower Pannonian’ and ‘Upper Pannonian’ sediments composed of coarse and fine-grained sand, sandstones and marls. The BM geothermal aquifers are the most important ones in the study area. The stable isotope δ2H and δ18O indicate that the monitored thermal waters have a meteoric origin, but without recent replenishment. Monitored waters belong to mixed hydrochemical types, from Na-ClHCO3 to Na-HCO3 types in the deep basin thermal waters and a CaMg-HCO3 type in the thermal waters from shallower parts. The study area has great geothermal potential. The estimated total available thermal power from Križevci, Velika-1 and the Daruvar spa is 70.5 MWt, but only 28 % of this thermal power is used. Since the predominant activity in the study area is agriculture, the geothermal resources available could lead to modern agricultural development and consequently contribute to increasing the standard of living of the local population. However, additional geophysical, geological, hydrogeological and hydrochemical investigations at a number of new potential locations are required to estimate the total available geothermal resources.


Download data is not yet available.

Article Details

Original Scientific Papers


ALJINOVIĆ, B. & BLAŠKOVIĆ, I. (1984): Comparison of sediment basis and the Mohorovičić discontinuity in the coastal area of Yugoslavia.− Nafta, Zagreb, 35, 65–71.

ARNORSSON, S. (2000): Isotopic and chemical techniques in geothermal exploration, development and use: sampling methods, data handling, interpretation.– Vienna: IAEA, 351 p.

BAĆ, J. & HERAK, M. (1962): Prijedlog za određivanje užih i širih zaštitnih zona termomineralnih izvora u Hrvatskoj [Proposal for determination of narrower and wider protection zones of thermomineral springs in Croatia – in Croatian].– Unpubl. Technical report, Archive of the Croatian Geological Survey.

BANCALARI, D. (1868): Das mineralbad Krapina Toeplitz in Croatien. Krapina spa and its warm springs and baths.– Vienna (in German), 85 p.

BOROVIĆ, S., POLA, M., BAČANI, A. & URUMOVIĆ, K. (2019): Constraining the recharge area of a hydrothermal system in fractured carbonates by numerical modelling.−Geothermics, 82, 128–149. doi: 10.1016/j.geothermics.2019.05.017

BOŠNJAK, R., ČUBRIĆ. S., GOLUB, M., GRABOVSKI, K., JELIĆ, K., KOLIN, I., KOŠĆAK, S., KULENOVIĆ, I., MIOČEV, D., PRAVICA, Z., RAJKOVIĆ, D., SALOPEK, B., SEČEN, J. & STANČIĆ, L. (1998): GEOEN – Program korištenja geotermalne energije [Programme of geothermal energy utilization – in Croatian].– Energy Institute Hrvoje Požar, Zagreb, 123 p.

CARTWRIGHT, I., WEAVER, T., TWEED, S., AHEARNE, D., COOPER, M., CZAPNIK, K. & TRANTER, J. (2002): Stable isotope geochemistry of cold CO2-bearing mineral spring waters, Daylesford, Victoria, Australia: sources of gas and water and links with waning volcanism.− Chem. Geol. 185, 71–91. doi: 10.1016/S0009-2541(01)00397-7

CARTWRIGHT, I., WEAVER, T.R., SIMMONS, C.T., FIFIELD, L.K., LAWRENCE, C.R., CHISARI, R. & VARLEY, S. (2010): Physical hydrogeology and environmental isotopes to constrain the age, origins and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia.− J. Hydrol., 380, 203–221. doi: 10.1016/j.jhydrol.2009.11.001

CROSCO (2009): Izvještaj o bušenju bušotine Dar-1 [Drilling report of the borehole Dar-1 – in Croatian].– Unpublished, Fund of professional documentation of Crosco, Zagreb.

CVETKOVIĆ, M., MATOŠ, B., RUKAVINA, D., KOLENKOVIĆ MOČILAC, I., SAFTIĆ, B., BAKETARIĆ, T., BAKETARIĆ, M., VUIĆ, I., STOPAR, A., JARIĆ, A. & PAŠKOV, T. (2019): Geoenergy potential of the Croatian part of Pannonian Basin: insights from the reconstruction of the pre-Neogene basement unconformity.− J. Maps, 15/2, 651–661. doi: 10.1080/17445647.2019.1645052

DARLINGe (2017-2019): Danube Region Leading Geothermal Energy project,

DOMENICO, P.A. & SCHWARTZ, F.W. (1990): Physical and Chemical Hydrogeology.– John Willey and Sons, New York, 824 p.

GORJANOVIĆ-KRAMBERGER, D. (1896): Geology and hydrogeology of the area of Stubičke Toplice. Zagreb.

GRUDELJ, A. (1890): Zaštitne zone termalnih izvora i kupelji Vraždinskih Toplica u Varaždinskoj županiji na putu prema Novom Marofu [Protection zones of the bathing area of the thermal springs in Varaždinske Toplice in the Varaždin County towards Novi Marof – in Croatian]. Zagreb, 25p.

HORVÁTH, F. (1993): Towards a mechanical model for the formation of the Pannonian Basin.– Tectonophysics, 225, 333–358. doi: 10.1016/0040-1951(93)90126-5

HUNJAK, T., LUTZ, H.O. & ROLLER-LUTZ, Z. (2013): Stable isotope composition of the meteoric precipitation in Croatia.– Isot. Environ. Health Stud., 49/3, 336–45. doi: 10.1080/10256016.2013.816697

INA (1966): Geološki i DTS izvještaj bušotine Ze-1 [Geological and DTS reports of well Ze-1 – in Croatian].– Unpublished, Fund of professional documentation of INA, Zagreb provided by Ministry of Economy and Energy, 25 p.

INA (1990): Geološki i DTS izvještaj bušotina VC-1 i VC-1A [Geological and DTS reports of wells VC-1 and VC-1A – in Croatian].– Unpublished, Fund of professional documentation of INA, Zagreb provided by Ministry of Economy and Energy 50 p.

JANKOWSKI, J., ACWORTH, R.I & SHEKARFOROUSH, S. (1998): Reverse ion exchange in deeply weathered porphyritic dacite fractured aquifer system, Yass, New South Wales, Australia.– In: AREHART, G.B. & HULSTON, J.R. (eds.): Proceedings of the 9th International Symposium on Water-Rock Interaction, Taupo, New Zealand, 30 March - 3 April, 1998. Rotterdam, A.A. Balkema, 243–246.

LARVA, O., MRAZ, V. & MARKOVIĆ, T. (2008): Daruvarske toplice - Elaborat utvrđivanja eksploatacijske izdašnosti Ivanovog vrela i objekta Š-3 [Daruvarske Spa - Study for determining the exploitation yields of Ivanovo vrelo and Š-3 – in Croatian].– Unpubl. Technical report, Archive of the Croatian Geological Survey, 10 p.

LARVA, O., MRAZ, V. & MARKOVIĆ, T. (2009): Hidrogeološki nadzor tijekom bušenja, ugradnje, čišćenja i pokusnog crpljenja istražno – eksploatacijke bušotine Dar-1 u Daruvaru [Hydrogeological monitoring during drilling, installation, cleaning and experimental pumping of the exploration-exploitation well Dar-1 in Daruvar – in Croatian].– Unpubl. Technical report, Archive of the Croatian Geological Survey, 12 p.

MAGYAR, I., RADIVOJEVIĆ, D., SZTANÓ, O., SYNAK, R., UJSZÁSZI, K. & PÓCSIK, M. (2013): Progradation of the paleo-Danube shelf margin across the Pannonian Basin during the Late Miocene and Early Pliocene.– Glob. Planet. Change, 103, 168–173. Doi: 10.1016/j.gloplacha.2012.06.007

MALJKOVIĆ, D. & GUDMUNDSSON J.R. (eds.) (2017): Geothermal Energy Utilisation Potential in Croatia by SANJA ŽIVKOVIĆ (EIHP), RUDOLF VAN HEMERT (EIHP), DRAŽEN TUMARA (EIHP), KARMEN STUPIN (EIHP), J. RÚNAR MAGNÚSSON (EFLA Consulting Engineers, Iceland), HEIMIR HJARTARSON (EFLA Consulting Engineers, Iceland), JILL ROBINSON HAIZLIP (Geologica Geothermal Group), MANON M. STÖVER, (Geologica Geothermal Group), EIHP, Zagreb, 57 p.

MALVIĆ, T. & VELIĆ, J. (2010): Relations between effective thickness, gas production and porosity in heterogeneous reservoirs: an example from the Molve Field, Croatian Pannonian Basin.– Pet. Geosci., 16, 41–51. doi: 10.1144/1354- 079309-722

MANDEL, S. & SHIFTAN, Z.L. (1980): Groundwater Resources: Investigation and Development.– Academic Press, New York, 269 p.

MARKOVIĆ, T. & LARVA, O. (2012): Hydrochemistry of thermal water in Daruvar area.– In: STEVANOVIĆ, Z. (ed.): Proceedings of 14th Serbian symposium of Hydrogeology with international participation, University of Belgrade, Mining and Geology Faculty, Belgrade, 187–191.

MARKOVIĆ, T., BOROVIĆ, S. & LARVA, O. (2015): Geochemical characteristics of thermal waters of Hrvatsko zagorje.− Geol. Croat., 68/1, 67–77. doi: 10.4154/GC.2015.05

MCLEAN, W. & JANKOWSKI, J. (2000): Groundwater quality and sustainability in an alluvial aquifer, Australia.– In: SILILO, A. (ed.): XXX IAH congress on groundwater: past achievements and future challenges. A.A. Balkema, Rotterdam.

MRAZ, V. (1983): Izvještaj o hidrogeološkim istražnim radovima na području Daruvarskih toplica II. faza [Report on hydrogeological exploration works in the area of Daruvar Spa II phase – in Croatian].– Unpubl. Technical report, Archive of the Croatian Geological Survey, 13 p.

NÁDOR, A., SEBESS-ZILAHI, L., ROTÁR-SZALKAI, Á., GULYÁS, Á. & MARKOVIĆ, T. (2020): New methods of geothermal potential assessment in the Pannonian basin.− Neth. J. Geosci., 98, e10. doi: 10.1017/njg.2019.7

OFFICIAL GAZETTE 153/09, 63/11, 130/11, 56/13, 14/14.– Water Act.

OFFICIAL GAZETTE 52/18, 52/19.– Exploration and Exploitation of Hydrocarbons Act.

OFFICIAL GAZETTE 56/13, 14/14.– Mining Act.

PAVELIĆ, D. (2001): Tectonostratigraphic model for the North Croatian and North Bosnian sector of the Miocene Pannonian Basin System.− Basin Res., 13, 359–376. doi: 10.1046/j.0950-091x.2001.00155.x

PRELOGOVIĆ, E., SAFTIĆ, B., KUK, V., VELIĆ, J., DRAGAŠ, M. & LUČIĆ, D. (1998): Tectonic activity in the Croatian part of the Pannonian basin.− Tectonophysics, 297, 283–293. doi: 10.1016/S0040-1951(98)00173-5

RAK, A. (1876): Krapinske toplice [Krapina spa – in Croatian].– Vienna 45 p.

RMAN, N. (2016): Hydrogeochemical and isotopic tracers for identification of seasonal and long-term over-exploitation of the Pleistocene thermal waters.− Environ. Monit. Assess., 188(4), 242. doi: 10.1007/s10661-016-5250-2

RMAN, N., GÁL, N., MARCIN, D., WEILBOLD, J., SCHUBERT, G., LAPANJE, A., RAJVER, D., BENKOVÁ, K. & NÁDOR, A. (2016a): Potentials of transboundary thermal water resources in the western part of the Pannonian basin.− Geothermics, 55, 88–98. doi: 10.1016/j.geothermics.2015.01.013

RMAN, N., LAPANJE, A., PRESTOR, J. & SULLIVAN, M.J.O. (2016b): Mitigating depletion of a porous geothermal aquifer in the Pannonian sedimentary basin.− Environ. Earth Sci., 75, 723. doi: 10.1007/s12665-016-5634-1

ROTÁR-SZALKAI, Á., MAROS, GY., BERECZKI, L., MARKOS, L., BABINSZKI, E., ZILAHI-SEBESS, L., GULYÁS, Á., KUN, É., SZŐCS, T., KERÉKGYÁRTÓ, T., NÁDOR, A., RAJVER, D., LAPANJE, A., ŠRAM, D., MARKOVIĆ, T., VRANJEŠ, A., FARNOAGA, R., SAMARDŽIĆ, N., HRVATOVIĆ, H., SKOPLJAK, F. & JOLOVIĆ, B. (2018): Identification, ranking and characterization of potential geothermal reservoirs.− Report of the DARLINGe project, 82 p. Available at

ROTÁR-SZALKAI, Á., NÁDOR, A., SZŐCS, T., MAROS, G., GOETZL, G. & ZEKIRI, F. (2017): Outline and joint characterization of transboundary geothermal reservoirs at the western part of the Pannonian basin.− Geothermics, 70, 1–16. doi: 10.1016/j.geothermics.2017.05.005

ROYDEN, L. (1988): Late Cenozoic Tectonics of the Pannonian Basin System.– In: ROYDEN, L. H. & HORVÁTH, F. (eds.): The Pannonian Basin (Memoir 45), American Association of Petroleum Geologists, 27–48.

SAFTIĆ, B., VELIĆ, J., SZTANO, O., JUHASZ, G. & IVKOVIĆ, Ž. (2003): Tertiary subsurface facies, source rocks and hydrocarbon reservoirs in the SW part of the Pannonian Basin (northern Croatia and south-western Hungary).− Geol. Croat., 56/1, 101–122. doi: 10.4154/232

SEBE, K., KOVAČIĆ, M., MAGYAR, I., KRIZMANIĆ, K., ŠPELIĆ, M., BIGUNAC, D., SÜTŐ-SZENTAI, M., KOVÁCS, Á., SZUROMI-KORECZ, A., BAKRAČ, K., HAJEK-TADESSE, V., TROSKOT-ČORBIĆ, T. & SZTANÓ, O. (2020): Correlation of upper Miocene-Pliocene Lake Pannon deposits across the Drava Basin, Croatia and Hungary.− Geol. Croat., 73/3, 177–195. doi: 10.4154/gc.2020.12

SZŐCS, T., RMAN, N., SÜVEGES, M., PALCSU, L., TÓTH, G. & LAPANJE, A. (2013): The application of isotope and chemical analyses in managing transboundary groundwater resources.− Appl. Geochemistry, 32, 95–107. doi: 10.1016/j.apgeochem.2012.10.006

ŠARIN, A. (1990): Tehnički izvještaj o pokusnom crpljenju termomineralne bušotine Kža-1 u Križevcima [Technical report on the pumping test at the well Kža-1 in Križevci – in Croatian].– Technical report, Archive of the Croatian Geological Survey.

ŠIMUNIĆ, A. (ed) (2008): Geotermalne i mineralne vode RH [Geothermal and mineral waters of the Republic of Croatia – in Croatian].– Croatian Geological Survey, Zagreb, 343 p.

ŠUMANOVAC, F., HEGEDŰS, E., OREŠKOVIĆ, J., KOLAR, S., KOVÁCS, A.C., DUDJAK, D. & KOVÁCS, I.J. (2016): Passive seismic experiment and receiver functions analysis to determine crustal structure at the contact of the northern Dinarides and southwestern Pannonian Basin.− Geophys. J. Int., 205, 3, 1420–1436. doi: 10.1093/gji/ggw101

ŠUMANOVAC, F., OREŠKOVIĆ, J., GRAD, M. & ALP 2002 Working Group (2009): Crustal structure at the contact of the Dinarides and Pannonian basin based on 2-D seismic and gravity interpretation of the Alp07 profile in the ALP 2002 experiment.− Geophys. J. Int., 179, 615–633. doi: 10.1111/j.1365-246X.2009.04288.x

ZANINOVIĆ, K., GAJIĆ-ČAPKA, M. & PERČEC TADIĆ, M. (2008): Klimatski atlas Hrvatske. Climate atlas of Croatia: 1961.–1990, 1971–2000.− Državni hidrometeorološki zavod. Zagreb, Croatia, 200 p.