engleski

Hydrogeological conditions of the Sava alluvial aquifer recharge and protection (broad Zagreb area, Croatia)

Within the broad Zagreb area, a Quaternary alluvial gravel-sandy aquifer filling the Sava river lowland forms the most significant hydrogeological unit. This aquifer accumulates a considerable amount of groundwater recharged by precipitation infiltration and percolation from the Sava river. The river recharge is much greater due to the pumping of large quantities of groundwater from several Zagreb pumping sites. The precipitation is infiltrated through covering silty-clayey deposits (aquitard) the thickness of which is smaller approaching the Sava, disappearing entirely in some places. The aquifer is exceptionally vulnerable to pollution from the land surface due to its hydrogeological properties, the small thickness of the covering aquitard, its lithological composition and the high urban and industrial agglomeration in this area. The paper describes the occurrence of this aquitard, its lithological composition and hydrogeological properties - the latter having the main role in vertical water transport and water quality protection. The text is supplemented with: a lithological cross section of Quaternary deposits filling the western part of the Sava tectonic depression, the isopach map of aquitard and a map showing aquifer vulnerability from surface pollution.

hydogeological conditions; alluvial aquifer; covering aquitard; aquifer recharge; water quality protection

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