Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia)
The aquifers of alpine karst and high karst plateaus are abundant water resources. They are difficult to characterise due to their complex, partly glaciokarstic, evolution in active tectonic environments, and an unsaturated zone up to two kilometres thick. We present and discuss the results of a tra...
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| Format: | Article |
| Language: | English |
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Slovenian Academy of Sciences and Arts
2023-12-01
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| Series: | Acta Carsologica |
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| Online Access: | https://ojs.zrc-sazu.si/carsologica/article/view/13348 |
| _version_ | 1797391696600760320 |
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| author | Franci Gabrovšek Matej Blatnik Nataša Ravbar Jana Čarga Miha Staut Metka Petrič |
| author_facet | Franci Gabrovšek Matej Blatnik Nataša Ravbar Jana Čarga Miha Staut Metka Petrič |
| author_sort | Franci Gabrovšek |
| collection | DOAJ |
| description | The aquifers of alpine karst and high karst plateaus are abundant water resources. They are difficult to characterise due to their complex, partly glaciokarstic, evolution in active tectonic environments, and an unsaturated zone up to two kilometres thick. We present and discuss the results of a tracing test in the alpine karst of the Julian Alps (Slovenia), more precisely in the Migovec System, the longest cave system in Slovenia (length = 43 km, depth = 972 m). The cave extends below a mountain ridge that separates the Soča and Sava Valleys, thus forming a topographic divide between the Adriatic and Black Sea basins, which gives the test greater regional significance. In early September 2019, three kilograms of uranine were injected into a perched lake in a remote part of the system, approximately 900 metres below the plateau and 100 metres above the low water table. All known springs in the valleys on either side of the mountain were monitored by manual or instrumental sampling and a field fluorometer. Due to the unexpectedly dry season, no tracer was detected at any site for two months until a heavy rainfall event in early November. Subsequently, about 60-65 % of the tracer mass appeared within 60 hours in the Tolminka River. No tracer was detected at other sites, either because
it was not present or because it was highly diluted. The study suggests that the lake containing the tracer is bypassed by the vadose flow and that the tracer was only mobilised during large events when the lake became part of the epihreatic flow. The linear peak flow velocity from the injection site to the Tolminka Spring was only about 1.7 m/h. However, assuming that the tracer was only mobilised by the large rain event, the velocity would be 70 m/h. The study highlights the challenges and pitfalls of water tracing in alpine karst systems and suggests ways to avoid them. |
| first_indexed | 2024-03-08T23:36:30Z |
| format | Article |
| id | doaj.art-1ba370376bda4909b2b7d3e3a46b3e8c |
| institution | Directory Open Access Journal |
| issn | 0583-6050 1580-2612 |
| language | English |
| last_indexed | 2024-03-08T23:36:30Z |
| publishDate | 2023-12-01 |
| publisher | Slovenian Academy of Sciences and Arts |
| record_format | Article |
| series | Acta Carsologica |
| spelling | doaj.art-1ba370376bda4909b2b7d3e3a46b3e8c2023-12-14T06:12:56ZengSlovenian Academy of Sciences and ArtsActa Carsologica0583-60501580-26122023-12-01522-310.3986/ac.v52i2-3.1334819327Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia)Franci Gabrovšek0https://orcid.org/0000-0001-8397-6487Matej Blatnik1Nataša Ravbar2Jana Čarga3Miha Staut4Metka Petrič5Research Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, SloveniaResearch Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, SloveniaResearch Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, SloveniaJamarska sekcija PD TolminJamarski klub Železničar, LjubljanaResearch Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, SloveniaThe aquifers of alpine karst and high karst plateaus are abundant water resources. They are difficult to characterise due to their complex, partly glaciokarstic, evolution in active tectonic environments, and an unsaturated zone up to two kilometres thick. We present and discuss the results of a tracing test in the alpine karst of the Julian Alps (Slovenia), more precisely in the Migovec System, the longest cave system in Slovenia (length = 43 km, depth = 972 m). The cave extends below a mountain ridge that separates the Soča and Sava Valleys, thus forming a topographic divide between the Adriatic and Black Sea basins, which gives the test greater regional significance. In early September 2019, three kilograms of uranine were injected into a perched lake in a remote part of the system, approximately 900 metres below the plateau and 100 metres above the low water table. All known springs in the valleys on either side of the mountain were monitored by manual or instrumental sampling and a field fluorometer. Due to the unexpectedly dry season, no tracer was detected at any site for two months until a heavy rainfall event in early November. Subsequently, about 60-65 % of the tracer mass appeared within 60 hours in the Tolminka River. No tracer was detected at other sites, either because it was not present or because it was highly diluted. The study suggests that the lake containing the tracer is bypassed by the vadose flow and that the tracer was only mobilised during large events when the lake became part of the epihreatic flow. The linear peak flow velocity from the injection site to the Tolminka Spring was only about 1.7 m/h. However, assuming that the tracer was only mobilised by the large rain event, the velocity would be 70 m/h. The study highlights the challenges and pitfalls of water tracing in alpine karst systems and suggests ways to avoid them.https://ojs.zrc-sazu.si/carsologica/article/view/13348karst aquiferunsaturated zonetracer testadriatic-black sea watershedjulian alps |
| spellingShingle | Franci Gabrovšek Matej Blatnik Nataša Ravbar Jana Čarga Miha Staut Metka Petrič Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) Acta Carsologica karst aquifer unsaturated zone tracer test adriatic-black sea watershed julian alps |
| title | Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) |
| title_full | Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) |
| title_fullStr | Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) |
| title_full_unstemmed | Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) |
| title_short | Unraveling the functioning of the vadose zone in alpine karst aquifers: New insights from a tracer test in the Migovec cave system (Julian alps, NW Slovenia) |
| title_sort | unraveling the functioning of the vadose zone in alpine karst aquifers new insights from a tracer test in the migovec cave system julian alps nw slovenia |
| topic | karst aquifer unsaturated zone tracer test adriatic-black sea watershed julian alps |
| url | https://ojs.zrc-sazu.si/carsologica/article/view/13348 |
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