Investigation of the hydrogeology of the pore aquifer in the Bodenbauer-St.Ilgen area using geophysical methods

Patrick Fachathaler

Research output: ThesisMaster's Thesis

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Abstract

The pore aquifer in the Bodenbauer-St.Ilgen area on the southern side of the Hochschwab Massif is of great significance for the water supply of the city of Graz and its neighboring municipalities. Hydrogeological investigations on the southern Hochschwab side in the 1970s and 1980s raised public interest in the potential of the water seeping into the subsoil in this area for the first time. The establishment of the Wasserverband Hochschwab Süd, nowadays known as the Zentral-Wasserversorgung Hochschwab Süd (ZWHS), laid the foundation for the development and utilization of this catchment area. Today, around 6.2 million m³/a, which correspond to around 195 l/s, are consumed by the surrounding communities. These hydrogeological investigations were carried out more than 40 years ago, which has increased the demand for further examination. The aim of this study was to identify the groundwater-bearing layers (Aquifer) in the Bodenbauer-St.Ilgen area, as well as the level of the groundwater table and the depth of the pre-Quaternary bedrock. Initially, two profiles were measured using geoelectrical resistivity tomography (ERT) during this thesis, which were later supplemented by two vertical electrical sounding (VES) profiles. The former profiles, designed to detect the water-bearing horizons in the Bodenbauer area, were positioned close to the seismic survey shot in the 1970s in order to ensure the best possible comparability. The results of the ERT verify the historical data along the first profile (hs01), as both a layered subsurface structure and an aquifer were detected. An answer to the previously unresolved question of a possible aquifer was found for profile hs02, which runs perpendicular to hs01, as the high resistivities indicate the presence of dry sediments and therefore not water-bearing layers. The depth soundings, positioned along the ERT profiles, were intended to determine the depth of the pre-Quaternary bedrock, but did not lead to the desired result, partly due to topographical constraints. The depth of the basin bedrock could not be determined either by the ERT or the VES for profile hs01. In the case of hs02, however, the possibility remains that the pre-Quaternary basement can be encountered at a depth of 100 m, due to the steeply dipping flanks. The results of these measurement campaigns generally agree well with those of the former investigations and can also answer previously unresolved questions, such as the presence and the distribution of groundwater-bearing layers.
Translated title of the contributionUntersuchung der hydrogeologischen Verhältnisse des Porenspeichers im Raum Bodenbauer-St.Ilgen mittels geophysikalischer Erkundungsmethoden
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Misch, David, Supervisor (internal)
Award date28 Jun 2024
DOIs
Publication statusPublished - 2024

Bibliographical note

no embargo

Keywords

  • Hochschwab
  • Bodenbauer
  • St.Ilgen
  • ZWHS
  • Hydrogeology
  • ERT
  • VES
  • Pore aquifer
  • pre-Quaternary basement

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