International Symposium on Mitigative Measures against Snow ...

<strong>International</strong> <strong>Symposium</strong> on Mitigative Measures against Snow Avalanches
Egilsstaðir, Iceland, March 11–14, 2008
Sustainable safety based on active risk management by a
controlled use of temporary measures
Alexander Ploner 1 *, Thomas Sönser 1 , Peter Sönser 1 and Werner Mauersberg 2
1 i.n.n. Ingenieurgesellschaft für Naturraum-Management mbH & CoKG,
Grabenweg 3a, A–6020 Innsbruck, AUSTRIA
2 Institute of Geography, University of Innsbruck, Innrain 52, A-6020 Innsbruck, AUSTRIA
*Corresponding author, e-mail: a.ploner (at) inn.co.at
ABSTRACT
The small village of Samnaun (Grisons, Switzerland) is the only settlement in the Alps where
the protection of permanent residential areas and major traffic routes threatened by potential
avalanches is predominantly based on temporary measures. In this context, remote avalanche
control systems, e.g. the so-called Wyssen Avalanche Towers play a key role by enabling a
supervised artificial release of avalanches by controlled explosive shots. Since 2001, 44 avalanche
towers have been installed in both the area above the settlement and the ski resort of
Samnaun, thus providing the data for a detailed analysis of such a new concept of avalanche
risk-management, which might be seen as a kind of paradigm change.
In a first step, pros and cons of a protection system which is strongly related to temporary
measures will be discussed. Key aspects, like the number of shots, the relation of snow fall
events, snow depth and shots, run-out dimensions will be demonstrated showing that this active
concept is the basis for a better control of the overall avalanche situation than traditional
ideas which are mostly based on a more passive attitude. Besides these technical and natural
scientific views, a major intension is laid on highlighting the legal situation in Switzerland in
general and in the province of Grisons defining the framing conditions for establishing such a
new protection system which is far beyond what has been applied so far in any country in the
Alps.
In a second step, potentials and limitation regarding the transferability of the strategy which
has successfully be applied in Samnaun to Austria will be discussed. As the laws and regulations
in Austria are different to the situation in Switzerland, the discussion of potentials and
limitation due to the legislation is a vital pre-requisite before starting to plan for applying this
new way of coping with avalanche related risks in Austria. As in the small village of Neustift
(Stubai, Tyrol), the environmental situation is somehow comparable to Samnaun, this settlement
is used as a test area.
Besides the legal and technical side, economical aspects will be discussed. A comparison of
overall costs related to the more classical mode of a prevention of the endangering processes
to the temporary measures is presented. This paper also highlights the sustainable character of
the new technology. In a final step, transferability to other mountain areas, e.g. Iceland, are
considered.
Ploner, Sönser, Sönser and Mauersberg 107