HYDROGEOLOGICAL AND HYDROCHEMICAL FEATURES OF KALNIK MASSIF

Kalničko gorje consists of Cretaceous – Holocene sediments, which can be in hydrogeological sense classified in three hydrogeological units: (1) northern area from central massive of Kalnik, consists of Cretaceous and low Miocene impermeable and low permeable sediments which are hydrogeological barrier and low permeable Cretaceous eruptive sediments ; (2) Kalnik massive consists of Paleogen and Baden permeable carbonate – clastic sediments, which are aquifer; (3) southern Kalnik area consists of Neogene low permeable sediments and Quaternary medium permeable unconsolidated deposits. In the hydrogelogical units are several aquifers types: (i) Paleogen carbonate aquifer consists of limestone – dolomite breccia and this is the most important aquifer in the Kalnik area; (ii) Baden carbonate aquifer consists of lithothamnium, lithothamnium limestone, sandstone and breccia-conglomerate and it has high permeability, especially through the karst morphological features; (iii) Quaternary alluvial aquifers – the most important is in the valley of the Kamešnica river and it’s permeability varies from poor to good depending on granulometric properties; (iv) Cretaceous eruptive aquifer from which in the Apatovac area is abstraction of mineral water. The aquifers of the Kalnik area are very vulnerable considering the hydrogeological properties of the area. Nevertheless, physical, physicalchemical, and chemical properties of groundwater in the Kalnik area are showing that waters are of very good quality. The reasons of good quality of waters are that the area is poorly populated and there is no potential pollutant. The area is very valuable and important natural resource for water supply of whole region. In the future it is necessary to provide good protection and sustainable water management to obtain today’s good quality and quantity of groundwater (the paper is published in Croatian)