22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

THE EPIPHREATIC FLOW IN MATURE KARST AQUIFERS: THEORY, MODELS AND OBSERVATIONS

26 Sep 2019, 15:00
15m
Conference room 2.1 ()

Conference room 2.1

Oral Topic 7 - Karst Hydrogeology Parallel

Speaker

Dr Franci Gabrovšek (ZRC SAZU Karst Research Institute)

Description

In many karst aquifers, the epiphreatic flow presents a major contribution to spring’s medium to high flow discharge. The flow follows a system of conduits and channels distributed in the transitional phreatic/vadose zone and shows very complex spatial and dynamic patterns. The flow regime frequently changes in all directions from pressurised to open channel and no flow conditions. Fast and high water level fluctuations are often encountered, particularly in tectonically active and structurally complex settings, such as in young orogens. There, solution conduits evolve in continuously changing boundary and structural conditions and are therefore far from equilibrium with the span of recharge. We present a set of simple hydraulic models to discuss possible flow situations in the epiphreatic zone. Concepts and consequences such as overflow phenomena, back-flooding, flow reversals etc. are presented. These concepts are demonstrated with a set of examples from several karst systems of Slovenian Dinaric karst. There, several long-term monitoring networks have been established in most caves with access to the epiphreatic flow. Caves often provide the only (yet demanding) access to the epiphreatic level, where installed autonomous loggers record physical and chemical parameters of groundwater. The analyses of these records in view of the basic hydraulic principles and known local geometry of the conduits system gives new insights into the dynamics and spatial distribution of flow within the aquifer. Finally, we also give an experience-based set of instructions on how and where to install instruments in caves to get the optimal data on the epiphreatic flow.

Primary authors

Dr Franci Gabrovšek (ZRC SAZU Karst Research Institute) Dr Matej Blatnik (ZRC SAZU Karst Research Institute) Dr Cyril Mayaud (Karst Research Institute Postojna)

Presentation Materials

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