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Franci Gabrov š ek , Matej Blatnik, Cyril Mayaud

The epiphreatic flow in mature karst aquifers: theory, models and observations. Franci Gabrov š ek , Matej Blatnik, Cyril Mayaud Karst Research Institute , Postojna, Slovenia. The epiphreatic zone. Observations in EZ: Relation : hydrographs <-> geometry. p, T, s. p, T, s.

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Franci Gabrov š ek , Matej Blatnik, Cyril Mayaud

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  1. The epiphreatic flow in mature karst aquifers: theory, models and observations Franci Gabrovšek, Matej Blatnik, Cyril Mayaud Karst Research Institute, Postojna, Slovenia

  2. The epiphreatic zone • Observations in EZ: • Relation: hydrographs <-> geometry p, T, s p, T, s p, T, s

  3. Characteristicsofthe epiphreatic zone • Speleogenetically most vivid part oftheaquifer. • Large conduitnetworks, major flowpaths. • In youngorogens: • Changingboundaryconditionsandstructure • Highhetereogeneity x-treme changes in geometry • Verticaldevelopment • Speleogenetic disequilibrium = channelscannotaccomodatefloods* *Gabrovšek F, Häuselmann P, Audra P (2014) ‘Looping caves’ versus ‘water table caves’: The role of base-level changes and recharge variations in cave development. Geomorphology 204 (0):683-691.

  4. Freesurfaceandpressurisedflow in conduits Saint-Vennanteqs. for open channel non-stationaryflow. Manning (orsimilar) eqs. for uniform stationaryflow: Rozos E, Koutsoyiannis,D (2006) JOURNAL OF HYDROLOGY n… roughnesscoefficient A… flowcross-section R… hydraulicradius … geometrical parameter …exponent > 1 foropen channelflow = 0.5 forpressurisedflow

  5. Detectionof o verflowchannels Transitionsbetweenflowregimes are recordedbyinflections in hydrographs!

  6. ModellingwiththeSWMM (Storm Water Management Model ) • EPA SWMM • SaintVenant‘s equations (1D, conservation of massandmomentum). • Network of conduits (links) connected at nodes. • Acccountsforpressurisedand open surfaceflow. • Versatility, open source, connectivity. ! Conduitflowonly!

  7. Overflows: a modellinginsight 1) A singleoverflow D2>D1 D1>D2

  8. Overflows: a modellinginsight 2) A doubleoverflow • Overflow (OF) is „seen“ at theObservationPoint (OP): • OF is down-flowfromthe OP, • OF is not back-flooded, • overflowshortcutsconsiderableheaddifference

  9. Case 1: Ljubljanica Catchment Focus on W1, W2, W3 ! • Blatnik et al., (2019) Groundwaterdynamicsbetween Planinsko Polje andspringsofthe Ljubljanica River, Slovenia. ActaCarsologica • (In Print.)

  10. Case 1: Ljubljanica Catchment

  11. Case 2: Kras/Carso • Highrechargevariability: Qmed =8,95 m3/s, Qmin = 0,16 m3/s, Qmax =387 m3/s • Highwaterlevelfluctuations( > 100 m) • Severalcavesreachingepiphreaticlevel. Gabrovšek F, Peric B, Kaufmann G (2018) Hydraulics of epiphreatic flow of a karst aquifer. Journal of Hydrology 560:56-74.

  12. Škocjan Caves- KačnaCave ?

  13. Škocjan Caves- KačnaCave Note thefast rise at P2 (KačnaCave), when Q is above 15 m3/s.

  14. Škocjan Caves- KačnaCave Qmax= 15 m3/s

  15. Škocjan Caves- KačnaCave: SWMM model

  16. Conclusions • Manyothersituationshavebeenobservedandinterpretedthisway: • Identificationandestimationof epiphreatic storage • Gabrovšek et al., (2018) Hydraulics of epiphreatic flow of a karst aquifer. • Journal of Hydrology 560:56-74 ; • Blatnik et al., (2019) Groundwaterdynamicsbetween Planinsko Polje and • springsofthe Ljubljanica River, Slovenia. ActaCarsologica,InPrint. • Mechanismsof polje flooding • Mayaud et al (2019).,.Understandingflooding in poljes : a modellingperspective. JournalofHydrology, vol. 575. • Identificationofflowbarriers • Blatnik et al., (2019) Groundwaterdynamicsbetween Planinsko Polje and • springsofthe Ljubljanica River, Slovenia. ActaCarsologica,InPrint. • Identificationandevaluationofcriticalconstrictions • (KaufmannG, Gabrovsek F, Turk J (2016) Modellingcaveflowhydraulics in Postojnska jama, • Slovenia. ActaCarsologica 45 (1):57-70. ) • Flowdistriburionbetween major springs • Hopeyouhaveheardprevious talk by B. Kogovšek. • Optimalpositioningofloggers

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