WATER EXPLORATION IN COASTAL KARST BY THE METHOD OF DOUBLE GRADIENT MAPPING

• Main Authors: Krešimir Jelić, Franjo Šumanovac, Mladen Lukačević
• Format: Article
• Language: English
• Published: Faculty of Mining, Geology and Petroleum Engineering 1991-12-01
• Series: Rudarsko-geološko-naftni Zbornik
• Subjects: Water exploration; Coastal karst; Gradient mapping
• Online Access: http://hrcak.srce.hr/index.php?show=clanak&id_clanak_jezik=38954&lang=en
• ISSN: 0353-4529; 1849-0409

Water exploration at several localities of the Adriatic karst sea-shore band was carried out by the dual gradient mapping of apparent electrical resistivity. By this method controlling the resistivity relation with depth by constant electric stream fields of different depth actions, the anomalies were obtained with apparent resistivity which can be related to deep karst fault zones, used as communication of water from coast background with off-shore springs and submarine springs. The advantage of this method in comparison with the usual geoelectric exploration methods of water in karst is, that electric fields are kept constant by lateral control of the apparent resistivity at some depth interval, which decreases the impact of surface inhomogenuities and electrically visible infrastructural constructions in urban environment on the correct interpretation of measured anomalies. The sea water as a big mass with low resistivity represents a disadvantage for geoelectrical exploration on the sea shore, which masks the explored anomalies at depth. Although, this anomalies can be recognised by this method. The report discusses the case of a successful exploration on the coastal area upwards of Opatija, where efforts have been made for many years to trap water flowing out of many off-shore and submarine springs (the paper is published in Croatian).