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Floods August 2005 in Switzerland
Bern 2005
Armin PetrascheckFederal office for water and geology
Causes of the floods was heavy rainfall in central Switzerland
The rainfall caused extreme discharges in rivers of the densely populated regions
Damage Areas 2005
Vulnerability: Danger for lifeFlood Statistics of Switzerland
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1972
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Year
Cas
ualit
ies
Out of 64 causalities 23 inside the house 41 outside26 wrong behavior13 in the car9 camping
Aug. 2005 6 victimsAverage. 2 Victims/year
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Years
Dam
age
of e
vent
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1000
2000
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9000
Sum
of d
amag
es
Damage Cor. Inflation Sum Sum with inflation
Swiss Flood Damage StatisticAug. 20052500 Mio. CHF
Sept. 1868 (TI, GR, UR, VS)
Juni 1910 (Deutschschweiz)
Aug. 1987 (UR, TI, VS)
Sept. 1993 (Oberwallis)
Sept. 1993 (Tessin)
Aug 1997 (Sachseln)
Mai 1999 (Deutschschweiz
Okt. 2000 (Wallis)
Okt. 2000 (Tessin)
0 20 40 60 80 100 Schäden der öffentlichen Hand private Schäden
800480580
80200650
1200
2500August 2005
Comparison of damages
Private
Public
Type of ImpactStatic Flooding
Damage parameter: water depth
Large areas affected
Type of ImpactStatic Flooding
High damage potential because of numerous cases but low risk for live
Type of ImpactStatic Flooding
Related damages:Furniture, machineryWalls, especially if oil is involved
Type of ImpactStatic Flooding
Defence by emergency barriers
Type of ImpactDynamic FloodingDamage parameter:Velocity and depth
High danger for live
Type of ImpactDynamic Flooding
Wood, sand and stones are transported by the water
Type of ImpactDynamic Flooding
Damages are increased by the dynamic forces. The impact of floating debris or stones or the erosion of fundaments may damage the structure
Type of ImpactDynamic Flooding
Defence byLocating on high ground,Permanent barriers orPrepared solid mobile elements
During large flood events the river can start to meander.
22. August 2005
Type of ImpactRiver bank erosion
Type of ImpactRiver bank erosion
High damage: Leads to destruction
Defence: River training measuresDeep foundations
Type of ImpactSlides and mudflow
Damage parameter:Depth of slideVolume of movement
Type of ImpactSlides and mudflow
DamageIn many cases complete destruction of the house
Type of ImpactSlides and mudflow
DefenceFor deep slides stabilization measures for the slide must be applied
For mudflows a reinforced wall on the backside can give good protection. Sometimes even temporary walls can keep the mud away from the building.
Type of ImpactDebris Flow
Large mass movements with high velocitiesDamage parameter Hight of deposition
Type of ImpactDebris Flow
Damage
High dynamic impact can cause complete destruction
Keep space for the torrent
No reconstruction of destroyedbuildings
Type of ImpactDebris Flow
Defence
Strong retaining walls
Swiss strategy1. Knowledge of hazard
Hazard maps show degree and extend
Bsp. Steinibach NW
Swiss strategy
2. Space for the river
Space enables increase of discharge capacity and ecological improvement
HQ
embankmentriverbed-breadth
embankment margin. stripe
maintenance / bufferstripe
riverside
3m 1:2 3m1:2
Swiss strategy
3. Reducing damages
3.1 Maintenance of rivers and protection structures to keep present safety level
3.2 Spatial planning measures to avoid an increase of damage potential
• keep free high endangered areas (red)• adapted construction and local protection (permanent or mobile) in medium and low endangered areas (blue and yellow areas• restricted land use in areas necessary for retention and emergency measures
River space
Free space forextreme floods
Protection
Swiss strategy
3.3 Protection measures
Increase safety where required,Include all types of measures in your planning and consider extreme events
Emergencyplanning
Improving dikes
Swiss strategy
3.3 Protection measures
consider extreme events
Swiss strategy
4. Emergency Planning
Be prepared for the unexpected
5. InsuranceTo enable reconstruction if the damage occurs
FLOODS
If you do notfind the strongman, who stops the flood, …... You have to livewith floods