engleski

Electrical imaging of faults in karst water explorations

Geophysical methods play a major role in hydrogeological explorations due to the fact that they enable, through the combination with other data, the obtaining of a reliable forecasting model and the detection of new drinking water resources. However, in order to exploit water and protect the sources (wells) in an appropriate manner, it is necessary to precisely define structural and lithological relations, i.e. define an accurate model of the underground. This is particularly difficult in complex geological models, which definitely include the karst terrain characterized by carbonate sediments, limestones and dolomites (Šumanovac and Weisser, 2001), whose primary features include marked surface nonhomogeneities and sudden lateral changes at small intervals. Surface nonhomogeneities are caused by the generation of high level noise, which results in the decreased quality of measured data, and thus a reduced accuracy of interpretation. The water in karst terrains is found mostly in fault and fracture zones, which are characterized by secondary porosity. A detailed mapping of these zones is therefore the primary task of geophysical explorations. The karst area covers the largest part of Croatia, and is related to the Dinarides in the southwestern and southern parts of Croatia. The general extension of the Dinarides is northwest-southeast, where the majority of tourist industry is concentrated, with high demands for drinking water in dry summer months. Although the youngest geophysical method, electrical tomography has already secured the top position in more shallow engineering geological explorations. Considering the good results already achieved in recent years in relatively deeper hydrogeological explorations in karst terrains, it has become the dominant geophysical method in these explorations, with other methods used as supplements, or for specific purposes. Therefore, based on numerous hydrogeological explorations in karst terrains, the detection and mapping of fault zones can be best performed by applying the electrical tomography method, whose great potentials are presented on characteristic cases of karst terrains and karst springs.

Electrical imaging; water exploration; karst; fault

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