engleski

An Assessment of Hydrogeological Parameters on the Karstic Island of Dugi Otok, Croatia

Extensive explorations have been performed on the northern part of the island of Dugi Otok in the Adriatic Sea (Croatia) with the purpose of extraction of fresh and/or brackish water. The island is predominantly composed of karstified carbonate rocks of the Cretaceous age. The explorations included geological and hydrogeological mapping of the area, geophysical surveys (by means of the geoelectric tomography method, electrical resistivity sounding and surface seismic refraction), exploratory core drilling, hydrochemical in situ and laboratory explorations, and the pumping test with the calculation of rock mass parameters. Based on the obtained results it was concluded that it is possible to exploit the groundwater with a pumping quantity of 5 l/s without intrusion of salt water into the fresh-water lens. Choosing a pumping regime based on the parameters of the aquifer (rock mass hydraulic conductivity order of magnitude 10-4 – 10-6 m/s), and knowing the parameters of the well as well as the tidal efficiency, should reduce to the minimum the possibility of intrusion. Because of the systematic quality of the performed explorations and the obtained results, the island of Dugi Otok can serve as typical example for such kinds of exploration works on other karstic islands. Hydrogeological composition behaves partly according to Ghyben-Herzberg`s law, but because of the nature of the karstic hydrogeological system such a statement needs to be accepted approximately because of the highly complicated relationships.

island; karst hydrology; pumping tests; geophysical surveys; salt-water intrusion; hydraulic conductivity

DOI 10.1016/j.hydrol.2007.06.008