The relationship of the geological framework to the Quaternary aquifer system in the Sava River valley (Croatia)

Abstract

Data from approximately 500 boreholes and an additional 40 wells for which there is a plausible range of data, facilitate description of the geometry of the Quaternary aquifer and its characteristics respectively, and pretension of the elements of the conceptual hydrogeological model in the Sava River valley. The aquifer heterogeneity is caused by tectonic activity and the depositional environments of the sediments within the valley. In the wider Zagreb area, gravel is the dominant component of the aquifer. Downstream from Zagreb, the aquifer is composed mainly of sand with sporadic intercalations of gravel. An admixture of silt and clay is not uncommon within the sand. The exceptions are alluvial fans that were formed by the right tributaries of the Sava River; gravel with sand is dominant in their lithological composition. The best hydrogeological properties of the aquifer system were registered in the vicinity of the Sava River, so all large pumping sites are located close to the river. The Quaternary aquifer is the main source of the water supply in the Sava River valley.