Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia

Blatnik, Matej; Mayaud, Cyril; Gabrovšek, Franci

doi:10.3986/ac.v48i2.7263

Cited by 9 publications

(7 citation statements)

References 15 publications

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“…S5 (B-B'). Postojna national meteorological stations (old and new) are located in a suburban flat terrain 1.2 km and 2 km SSW from the main entrance (not shown) Gallino (1924) to Planina Cave where it discharges onto Planinsko Polje, a part of the catchment area of the Ljubljanica springs (Blatnik et al 2019;Šebela 2019). The cave has two different levels, a lower (epi)phreatic and an upper dry level that is visited by about 800,000 tourists per year.…”

Section: Introductionmentioning

confidence: 99%

CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

Kukuljan

Gabrovšek

Covington

et al. 2021

Theor Appl Climatol

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Understanding the dynamics and distribution of CO2 in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO2. We show (1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and (2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO2. Namely, in the terminal chamber of the passage, the pCO2 is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rates and pCO2, which enter via small conduits and fractures embedded in a CO2-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO2 inflows, high and persistent gradients in pCO2 are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m are observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.

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Section: Introductionmentioning

confidence: 99%

CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

Kukuljan

Gabrovšek

Covington

et al. 2021

Theor Appl Climatol

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“…1). It is an active stream cave fed by the allogenic Pivka River (511 m a.s.l., Q avg ≈ 5 m 3 /s) and is hydrologically connected to Planina Cave where it discharges onto Planinsko Polje, a part of the catchment area of the Ljubljanica springs (Blatnik et al 2019;Šebela 2019). The cave has two different levels, a lower (epi)phreatic and an upper dry level that is visited by about 800,000 tourists per year.…”

Section: Study Sitementioning

confidence: 99%

CO2 Dynamics and Heterogeneity in a Cave Atmosphere: Role of Ventilation Patterns and Airflow Pathways

Kukuljan

Gabrovšek

Covington

et al. 2021

Preprint

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Understanding the dynamics and distribution of CO2 in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO2. We show 1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and 2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO2. Namely, in the terminal chamber of the passage, the pCO2 is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rate and pCO2, which enter via small conduits and fractures embedded in a CO2-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO2 inflows, high and persistent gradients in pCO2 are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m is observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.

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“…The Idrija Fault Zone forces the groundwater to surface, which led to the formation of a series of Dinaric Poljes, with springs and ponor zones at the rims and over-crossing superficial streams Blatnik et al 2017;Blatnik et al 2019).…”

Section: Unica Catchmentmentioning

confidence: 99%

Understanding the temporal variation of flow direction in a complex karst system (Planinska Jama, Slovenia)

Kaufman

Mayaud

Kogovšek

et al. 2020

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Karst aquifers are abundant, but vulnerable water resources. Therefore, a deeper understanding of possible mechanisms that determine the properties of karst springs is crucial. In this work, we present an example of Unica Spring and Malni Spring, the two main outlets of a large karst system in the Notranjska karst region, Slovenia. Although the two springs share same catchment area, the flow distribution between them shows an interesting behaviour: At low-flow conditions, Malni Spring is the main outlet, while Unica spring receives almost no water. During high water events, discharge of Malni Spring stays limited and Unica Spring becomes the main outlet. We relate these observations to the local geometry of the channels and breakdowns in the remote part of the Planinska Jama (Planina Cave), called Mysterious Lake. There, waters from Rakov Škocjan and Javorniki aquifer merge and further diverge to both springs. At low water conditions, the outflow towards the Unica Spring is restricted by the breakdown, so that most of the inflow is directed towards the Malni Spring. With increasing recharge, the level in Mysterious Lake rises until the water starts to flow over the breakdown along a system of large channels (Rak Branch of Planinska Jama) to the Unica Spring. The breakdown level keeps the hydraulic head and the flow towards Malni Spring limited. To verify this scenario, a hydraulic conduit model was made based on the known and predicted channels, and inflows calculated from the historical data of discharge measurements at related springs and ponors. An inversion procedure was used to obtain a satisfactory fit to the observed discharge data and to constrain the selected model parameters. The model accurately reproduced the observed discharge behaviour under low- andhigh-flow conditions.

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Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia

Cited by 9 publications

References 15 publications

CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

CO2 Dynamics and Heterogeneity in a Cave Atmosphere: Role of Ventilation Patterns and Airflow Pathways

Understanding the temporal variation of flow direction in a complex karst system (Planinska Jama, Slovenia)

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