TY - JOUR

T1 - Gravimetry and hydrologic data to constrain the hydrodynamics of a karstic area

T2 - The Škocjan Caves study case

AU - Pivetta, Tommaso

AU - Braitenberg, Carla

AU - Gabrovšek, Franci

AU - Gabriel, Gerald

AU - Meurers, Bruno

N1 - Funding Information: For this project Tommaso Pivetta benefited from a fellowship cofounded by Regione Friuli Venezia Giulia (Italy) and the European Social Fund (regional code: F17101346001). The authors acknowledge the project L7-8268 (Karst research for sustainable use of Škocjan Caves as World heritage) that was financially supported by the Slovenian Research Agency. Detlef Vogel and Jan Bergmann-Barrocas are greatly acknowledged for the installation and maintenance of the station acquisition system. The reviews of Gerhard Jentzsch and one anonymous reviewer greatly helped to improve the manuscript.

PY - 2024/2

Y1 - 2024/2

N2 - In this paper we employ a combination of gravity and hydrologic data to constrain a hydraulic model of the Škocjan Caves, an allogenic dominated karstic system in Slovenia. The gravity time-series recorded by a spring-based gravimeter, are carefully analyzed to remove tidal and non-tidal effects and unveil the local hydrologic contribution, which is influenced by the temporary accumulation of water in the cave system during the flood events of the Reka river. We make use of a combined analysis of three large flood events with peak river discharge of about 200, 230 and 300 m3/s, that caused significant water level and gravity variations sensed by the pressure transducer and by the gravimeter. By the integration of hydraulic modelling we study the different coupled gravimetric-hydrologic responses to these flood events: we show that, depending on the peak discharge and duration of the event, different flow conditions are present in the cave system. In addition to the information provided by the pressure transducer, the gravimeter is sensitive to the flow dynamics in a different sector of the cave due to the choice of its location; this configuration helps to better constrain the hydraulic model. Moreover, we find that the autogenic recharge by percolating water can significantly affect the gravity time-series and must be considered in related models. By inclusion of both the hydraulic model outcomes and of the modelling of the autogenic recharge, we are able to better explain the gravity transients during the two smaller magnitude events. In particular, during such events the autogenic contribution produces a transient gravity signal, which is about 4 times larger than the allogenic one, while during the largest flood the allogenic contribution drastically overcomes the autogenic effect by a factor 20. By discussing this case, we prove the potential of terrestrial gravity observation to depict the hydro-dynamics of these complex karstic systems as well as the potential of gravimetry to remotely monitor these storage units.

AB - In this paper we employ a combination of gravity and hydrologic data to constrain a hydraulic model of the Škocjan Caves, an allogenic dominated karstic system in Slovenia. The gravity time-series recorded by a spring-based gravimeter, are carefully analyzed to remove tidal and non-tidal effects and unveil the local hydrologic contribution, which is influenced by the temporary accumulation of water in the cave system during the flood events of the Reka river. We make use of a combined analysis of three large flood events with peak river discharge of about 200, 230 and 300 m3/s, that caused significant water level and gravity variations sensed by the pressure transducer and by the gravimeter. By the integration of hydraulic modelling we study the different coupled gravimetric-hydrologic responses to these flood events: we show that, depending on the peak discharge and duration of the event, different flow conditions are present in the cave system. In addition to the information provided by the pressure transducer, the gravimeter is sensitive to the flow dynamics in a different sector of the cave due to the choice of its location; this configuration helps to better constrain the hydraulic model. Moreover, we find that the autogenic recharge by percolating water can significantly affect the gravity time-series and must be considered in related models. By inclusion of both the hydraulic model outcomes and of the modelling of the autogenic recharge, we are able to better explain the gravity transients during the two smaller magnitude events. In particular, during such events the autogenic contribution produces a transient gravity signal, which is about 4 times larger than the allogenic one, while during the largest flood the allogenic contribution drastically overcomes the autogenic effect by a factor 20. By discussing this case, we prove the potential of terrestrial gravity observation to depict the hydro-dynamics of these complex karstic systems as well as the potential of gravimetry to remotely monitor these storage units.

KW - Hydraulic modelling

KW - Hydrogeodesy

KW - Karst aquifer

KW - Terrestrial gravimetry

UR - http://www.scopus.com/inward/record.url?scp=85180550867&partnerID=8YFLogxK

U2 - 10.1016/j.jhydrol.2023.130453

DO - 10.1016/j.jhydrol.2023.130453

M3 - Article

AN - SCOPUS:85180550867

VL - 629

JO - Journal of hydrology

JF - Journal of hydrology

SN - 0022-1694

M1 - 130453

ER -