Hydrogeological Relationships of the Golubinka Karst Spring in Ljubač Bay, Dalmatia, Croatia

Abstract

The Golubinka spring is a typical karst spring situated in northernDalmatia, Croatia. The catchment area is mostly composed of limestonesof the Cretaceous and Palaeogene, with some dolomitic parts.Hydrogeological barriers are composed of flysch or Quaternarysediments, and most of them are “hanging” barriers, so that the karstwater can flow underneath. Many spelaeological features in the vicinityof the spring point to a typical karst conduit flowing under ground.This has been proven by tracer tests, because a connection exists tothe periphery of the catchment with an apparent velocity of 8.1 cm/s.The whole area is situated in the Mediterranean climatic belt, so theprecipitation distribution is quite unfavourable – summers are long,hot and dry. This is why the summer seasons usually end with seawater intrusion into the aquifer with a significant increase in chlorideion concentration. Since the spring is capped for water supply, there isa bulk monitoring system established. The data obtained were processed by means of multivariate analysis, and three main types of quality deterioration were recognized. The first is connected with pollutionfrom agriculture and inhabited areas without sewage, the secondrepresents occasional sea water intrusions, while the third relates toheavy rainfall events accompanied by turbidity and pollution. Togetherwith the other conclusions, these results should have a practicalpurpose primarily in the matter of water protection.