Explanatory notes to the digital geological map of the Rax ... - KATER

KATER II Geology of the Rax-Schneeberg-region
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Introduction
The inhabitants (about 1.65 million people) of the Austrian capital city Vienna become
supplied with high quality drinking water from karstic springs. Up to 200.000 cbm per day are
flowing via each of the two pipelines 150 resp. 180 kilometers from the Northern Calcareous
Alps towards Vienna. The protected area around the springs comprises about 32.000 hectars
of karstified mountain ranges, a sensible ecosystem with complex interactions between
rocks, water, soil, vegetation, climate and human landuse.
Water supply agencies permanently have to balance between saving water quality and
quantity, economic requirements and monitoring of environmental pollution. To maintain at
least a minimum water supply in case of local pollution it is necessary to have a better
understandig of the catchment areas of individual springs and of the potential subterranean
water paths.
About 1990 the government of Vienna has initiated a multidisciplinary “Karst Research
Project”. Within this frame the Austrian Geological Survey has started a detailed geological
mapping of the catchment area of the Second Vienna Water Supply System. The final report
2002 offers a modern geological map of about 520 sq.km area of the Hochschwab mountain
range in form of a digital database.
In the meantime the Karst Research Project of the Government of Vienna has initiated a
transnational and interdisciplinary project on European level, due to its fundamental
significance for municipal water supply systems. The aim of KATER (KArst waTER research
program in the frame of EU Interreg II c) was to form the basic tools for a decision finding
system in the field of regional policy, water supply and environment protection – basics like
definition of metadata, cartographic standards and GIS (Geographic Information Systems) -
tools.
The following project KATER II (in the frame of EU Interreg III b CADSES) has the aim of
developing a GIS-based decision system to estimate or quantify the influences of land use
activities on drinking water ressources in karstified areas.
As a part of this project the geology of the catchment areas of the First Vienna Water Supply
System has to be investigated in a similar way as in the former Hochschwab project. Data
integration of available modern maps and additional geological mapping with a focus on the
Schneeberg area was done by the Austrian Geological Survey, starting in december 2003.
The final report presents the results in form of a geological map 1:25.000, four geological
cross sections and explanatory notes. The geological map is also available as a digital
database (ArcGis9/GeoDatabase).
Within the karst water system the geological setting is responsible for the collection, filtering,
storage and distribution of karst water on its way down from the surface through the
permeable rock to the spring. The petrography of rocks and the geometry of their structural
features has influence on the water paths and the position of springs and the chemistry of
rocks may also affect water quality.
The large karstified areas of the Northern Calcareous Alps are composed mainly of thick
sequences of shallow water carbonates of seemingly monotonous lithology. Only a very
general overall fiew could be obtained from older geological maps. No detailed knowledge
existed about structures like internal thrusts or fault systems and about the geometry of
internal lithological aquitards/aquicludes.
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