The north-western sector of the Friuli Venezia Giulia Region, on the border between Italy and Austria, is characterized by the presence of an extensive mountain massif where outcrop the intensely karstified Devonian limestones. The high average rainfall, together with the high permeability of carbonates, has favored the development of an extensive aquifer, the main source of which is represented by the Fontanon di Timau. Due to its high flow rate, between 250 and 5000 l/s, the spring is exploited both for the supply of drinking water and hydroelectric energy. Given the importance of the source, a research project has started, partially funded by the Geological Service of the Friuli Venezia Giulia Region, aiming at the hydrogeological characterization of the survey area in order to identify the its recharge area and evaluate its vulnerability. The present paper proposes a hydrogeochemical characterization of precipitation, surface waters and springs in the area located between Mt. Coglians and the Alta Valle del But, and between Eiskar glacier, the valley of the Valentina and the Anger valley for the Italian and Austrian sectors, respectively. The study was carried out over a period of about 5 years, during which a hydrogeological survey was carried out in order to identify all the sources present in the area and to design a geochemical monitoring network of the waters. Thanks to special rain gauges, monthly precipitations were collected for the isotopic composition analysis in order to determine the isotopic gradient of the area (Plocken, Mt. Croce Carnico, and Rivo). Surface and spring water samples were collected for the study of stable (O and H), unstable (3H) isotopes, radionuclides (Rn), major and trace elements. The trends related to the temperature and electrical conductivity of the water in correspondence of different sampling points were also defined. At the same time, tracing tests were also performed using uranine and tinopal, which made it possible to verify the hydrogeological connection between the western sector of the karst area and the Fontanon di Timau and to define the hydrodynamics of the underground system. Isotopes and trace element results highlighted that Fontanon di Timau spring is significantly fed by the massif of Mt. Coglians-Creta di Collinetta as well as by the waters that infiltrate the area of Pal Piccolo-Creta di Timau and partially also from the waters that infiltrate beyond the watershed in Austrian territory. All the other springs identified in the area, on the other hand, have much lower flow rates and drain waters from neighboring basins limited to the Italian side only.
Geochemical characterization of the Timau Karst aquifer
Karlicek D.
;Zini L.;Terribili L.;Calligaris Chiara;Finocchiaro F.;Pavoni E.;
2021-01-01
Abstract
The north-western sector of the Friuli Venezia Giulia Region, on the border between Italy and Austria, is characterized by the presence of an extensive mountain massif where outcrop the intensely karstified Devonian limestones. The high average rainfall, together with the high permeability of carbonates, has favored the development of an extensive aquifer, the main source of which is represented by the Fontanon di Timau. Due to its high flow rate, between 250 and 5000 l/s, the spring is exploited both for the supply of drinking water and hydroelectric energy. Given the importance of the source, a research project has started, partially funded by the Geological Service of the Friuli Venezia Giulia Region, aiming at the hydrogeological characterization of the survey area in order to identify the its recharge area and evaluate its vulnerability. The present paper proposes a hydrogeochemical characterization of precipitation, surface waters and springs in the area located between Mt. Coglians and the Alta Valle del But, and between Eiskar glacier, the valley of the Valentina and the Anger valley for the Italian and Austrian sectors, respectively. The study was carried out over a period of about 5 years, during which a hydrogeological survey was carried out in order to identify all the sources present in the area and to design a geochemical monitoring network of the waters. Thanks to special rain gauges, monthly precipitations were collected for the isotopic composition analysis in order to determine the isotopic gradient of the area (Plocken, Mt. Croce Carnico, and Rivo). Surface and spring water samples were collected for the study of stable (O and H), unstable (3H) isotopes, radionuclides (Rn), major and trace elements. The trends related to the temperature and electrical conductivity of the water in correspondence of different sampling points were also defined. At the same time, tracing tests were also performed using uranine and tinopal, which made it possible to verify the hydrogeological connection between the western sector of the karst area and the Fontanon di Timau and to define the hydrodynamics of the underground system. Isotopes and trace element results highlighted that Fontanon di Timau spring is significantly fed by the massif of Mt. Coglians-Creta di Collinetta as well as by the waters that infiltrate the area of Pal Piccolo-Creta di Timau and partially also from the waters that infiltrate beyond the watershed in Austrian territory. All the other springs identified in the area, on the other hand, have much lower flow rates and drain waters from neighboring basins limited to the Italian side only.Pubblicazioni consigliate
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