austrian service for torrent and avalanche control · avalanche control watershed management rock...

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AUSTRIAN SERVICE FOR TORRENT ANDAVALANCHE CONTROL

Thomas Fink

Federal Ministry – Republic of Austria, Sustainability and Tourism

Directorate III/5 – Torrent and Avalanche Control and Protection Forest Policy

18th June 2019

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CHARACTERISTICS / BOUNDARY CONDITIONS

• Austria: 2/3 alpine; only 37 % available for permanent settlement (especially

valleys and low land regions)

• pot. high precipitation (altitude)

Präsentationstitel 2Typical alpine valley

Amount of the preciptitation mm/a

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Natural risks in Austria

• about 400.000 objects are endangered from natural risks

• Death risk of some natural risks in Austria:

− Avalanches: 2,10 x 10-4 (~ 30 deaths/y) (espescially while skiing in unprotected areas)

− Lightning strike: 2,00 x 10-6

− Flood: 5,00 x 10-7

• Economic deficits in case of weather extremes in the last

20 years ~ 9.5 Mrd EUR (detected of Munich re-insurance

company)

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ALPINE NATURAL HAZARDS IN AUSTRIA - FACTS AND FIGURES

• Austria in general is exposed to heavy precipitation, floods, debris flow,

thunderstorms, hail and storm; snow avalanches in winter season

• 100.000 km of rivers and creeks and about 9.000 lakes are known

• 70% of total area is part of torrent and snow avalanche catchment areas

• 12.000 torrent catchments and 7.000 well-known snow avalanche paths are

documented

• Landslides and rock-fall potential in steep slopes depending on the geologic

situation

• Austrian Service for Torrent and Avalanche Control (WLV) was founded in 1884 as

a department of the k & k (imperial) Ministry of Agriculture (today Ministry of

Agriculture, Forestry, Environment and Water Management in Vienna)

• Torrents and avalanches are federal tasks according to Art. 10 of the Austrian

constitution4

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Disaster Cycle

• The goal of all measures is the reduction of risks and an increase of the security

against natural hazards

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The need of protection in alpine regions is constantly increasing.

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torrent control avalanche control rock fall control landslide control

We differ four „types of disasters“

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Planning prevention measures

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Using modern construction programs and presentation systems

Using hydrological detail analysis

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Structural Measures

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Structural measures –torrents

In torrential catchment areas

dams are built to stabilise the

beds of torrents against depth

erosion and to retain

sediments and woody debris.

Furthermore, dams to “dose”

flood discharge and sediment

transport as well as to “break”

the force of landslides are

used.

In densely settled areas it may

sometimes be necessary to

develop the discharge section

(regulation) or stabilise banks9

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Structural measures –avalanches

Snowpack-stabilising

structures are built using

steel, wood or steel nets

(wires).

In the runout zone of

avalanches deflecting dams

and catchment basins force

flowing avalanches to

deposit outside the

threatened residential area.

To protect highways and ski

areas also temporarily

effective techniques for the

artificial (targeted)

triggering of avalanches are

applied.10

http://www.google.at/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi1j5_kk7XTAhUCSBQKHYkNBaAQjRwIBw&url=http://www.tt.com/panorama/gesellschaft/12432074-91/lawinen-als-st%C3%A4ndige-begleiter.csp&psig=AFQjCNGhtVDFOA5gKQGeJzkOd7Sw7WrKKQ&ust=1492850538808308

http://www.google.at/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj5nsuUlLXTAhUHrRQKHa8yACgQjRwIBw&url=http://www.kitzbuehel.eu/Neue_Lawinensprenganlage_am_Steinbergkogel&psig=AFQjCNGlDK2JfGHeIwi6iruHbn_a_5sjLg&ust=1492850639413954

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Structural measures - erosion

The protection against rockfall is provided

by means of steel nets which catch stones

in the process of falling. Catching dams

are built to ensure the safe deposit of

rockfalls.

Slides occur frequently in connection with

the escaping of water from a slope;

therefore the drainage of the sliding

block is one of the most efficient

techniques of slide stabilisation.

Furthermore, technical protection

structures like anchors, arrays of posts or

barriers are used to give slopes the

necessary stability.

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Structural measures –forests

Forests are the best possible kind of

vegetation to reduce runoff- and erosion

processes, for rock-fall protection and

protection against avalanches.

20% of the Austrian forests are so called

„protection forests“, that means: forests,

which protects against several risks. Austria

has approximately 0,1 ha protection forest per

habitant.

Frequent problems in protection forest

management are overaged forests, missing

regeneration (because of too high poulations

of hoofed game as deer and chamois), poor

assesibality, unfavorable tree combination and

poor vitality in case of the high sea level12

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Structural measures –forests

• For the management of protection

forests some specific forest

techniques, like the transverse

felling of trees and cutting high,

were developed (increasing the

roughness of the surface).

• Land use management measures:

Technical support measures for

immediate effects of protection.In

their shelter – silvicultural measures

for a long-term realisation of a

stabile protection forest. Long

project periods (15 – 30 years), long

regeneration periods.

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Land use management measures - examples

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Example afforestation “Schmittenbach” (Zell am See, Salzburg), uplifting of the timer-line

1887

2007

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FOREST DEVELOPMENT PLAN – www.waldentwicklungsplan.at

OSWI: BASIS = WEP S3 UND (S2)

Maßstab: 1:50.000Revision: ca. alle 10 Jahre

WEP App

http://www.waldentwicklungsplan.at/

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Example Integrated Project “Protection forestHallstatt“ (Hallstatt, Oberösterreich)

combination of avalanche-and rockfall measures withsilvicultural measures

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Example FWP “Hochtannberg“ (Schröcken, VBG)

combination of avalanche andsilvicultural measures(reafforestation and forestrestoration)

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Land use management measures – cost effect

Für einen Zeitraum von 10 Jahren ist zur gesamten Schutzwaldsanierung in Österreich die Schutzwaldmilliarde erforderlich !(Schätzungen aus den Landes-Schutzwaldkonzepten)

Der derzeitige Deckungsbeitrag aus öffentlichen Mitteln liegt bei rund 17 %

Costs of the protection against avalanches per ha

about € ~ 600.000

10-timesof the total costs for

restoring protection forests

or 100-times of the costs to receive the positive

effects of protection forests

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Investments in Austrian’s natural hazard prevention

54%

14%

11%

17%

4%

Expenses for Categories of Measures

Torrent Control

Avalanche Control

WatershedManagement

Rock fall, LandslideControl

Planning

Every year in

Austria approx.

€ 200 Mio. of

federal subsidies

are invested for

preventive

measures

including also

maintenance.

Torrent and

avalanche control

~ € 80 Mio, Water

Management and

Flood Protection ~

€ 120 Mio

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Alpine Hazards and Climate Change – heavy preciptiation

Alpine Naturgefahren und Klimawandel 20

1st August 2018Pettneu am Arlberg

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• Event Schnannerbach / Pettneu a. A. / TIROL

• 1st Aug. 2018 110.000 m³ solids

• catchment area: 6,58 km²

• av. slope: 18° (~ 33 %)

• max. elevation: 2.887 m.a.s.l.

• min. elevation: 1217 m.a.s.l.

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1992: slot barrier

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1992: slot barrier2014: adaption of slots

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SedimentsDesign event (HQ150): 40.000 m³

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SedimentsDesign event (HQ150): 40.000 m³1st August 2018: 110.000 m³

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SedimentsDesign event (HQ150): 40.000 m³1st August 2018: 110.000 m³80.000 m³ behind slot barrier

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SedimentsDesign event (HQ150): 40.000 m³1st August 2018: 110.000 m³80.000 m³ behind slot barrier10.000 m³ in channel

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SedimentsDesign event (HQ150): 40.000 m³1st August 2018: 110.000 m³80.000 m³ behind slot barrier10.000 m³ in channel

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SedimentsDesign event (HQ150): 40.000 m³1st August 2018: 110.000 m³80.000 m³ behind slot barrier10.000 m³ in channel20.000 m³ in preflooder

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1st August 2018: 110.000 m³Only few damages, no casualtiesthanks to a functional protection structure

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ThoughtsWhat happens if second event hits the Schnannerbach within days?

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Alpine Hazards and Climate Change – thawing permafrost

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ObersulzbachThawing permafrost SattelkarCombe: 2.130 – 2.730 m ü.A.Debris cone: 1.610 – 1.920 m ü.A.

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ObersulzbachThawing permafrost SattelkarCombe: 2.130 – 2.730 m ü.A.Debris cone: 1.610 – 1.920 m ü.A.

Scenario 1: annual bedload input35.000 – 70.000 m³

Scenario 2: sudden discharge: up to 600.000 m³

Estimated transport capacity ofObersulzbach during flood event: 100.000 m³ ?

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Ofenkar Mitterkar Steinkar

Sattelkar

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Alpine Hazards and Climate Change – protection forest


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• HIER weitermachen mit Schutzwald Sturmkatastrophe


Kals/Osttirol: windfall 29./30.10.2018

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Alpine Hazards and Climate Change – forest fire


EchernwandGem. Ebensee: 21.08.2018

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Alpine Naturgefahren – facing challenges


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Obertauern 1952-1954

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Obertauern 2017

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Alpine Naturgefahren – facing challengesecological aspectsÖkologische Aspekte


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THANKS FOR YOUR

ATTENTION.

Thomas Fink

Federal Ministry – Republic of Austria, Sustainability and Tourism

Directorate III/5 – Torrent and Avalanche Control and Protection Forest Policy

18th June 2019

austrian service for torrent and avalanche control · avalanche control watershed management rock...

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