Date post: | 03-Jul-2015 |
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Assessment of Risks on transportation Networks resulting from
slope Instability and Climate change in the Alps
Main objectives
A. Document current DF/shallow landslide activity in the Alps
B. Consequences on transportation network
C. Definition of RCM future climate scenarios
D. DF response considering future climate conditions and lande use planning
E. Help to practical users users
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3 key regions
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1- French Alps
(Haute-Durance, Savoie)
2- Eastern Italian Alps (Tagliamento and Adige rivers)
3- Swiss Alps (Zermatt valley)
Grenoble
Briançon
Geneve
Italy
3- Swiss Alps (Zermatt valley)
Method: point A (Current DF/landslides activity)
Current DF databases (historical archives –tree ring)
Current climate conditions
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- Observed climate data
- Reanalyses climate data
- 27 RCMs downscaled scenarios
France Italy Switzerland
650 DF from 1970 50 DF from 1990s 250 DF+ from 1850
Methods: point A (DF/landslides activity related to
current climate conditions)
In the 3 regions
– Probabilistic and Deterministic models of occurrence at local scale (Shallow landslide model) considering climatic components
– Probabilistic model of occurrence at meso scale (logit simple or hierarchic model) considering climatic and geomorphologic components
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Main results: landslides local scale
Landslide suseptibily considering different precipitation scenarios
defined from meteo stations
Main results : Landslides local scale
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Ubaye Valley - Southern French Alps
7 shallow forested landslides sampled in the Riou Bourdoux catchment
759 pine trees - 3096 cores sampled
1298 growth disturbances dated
Main results: landslides local scale
Landslide reactivation related to temperature anomalies
during spring
Evolution suggests a shift from snowmelt-induced landslides
(controlled by winter precipitation) to reactivations controlled
by spring temperatures
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N = 61
Local scale with current meteorological conditions (I/D of precipitation analysis)
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Precipitation during each event
Main results point A: occurrence of Debris flows-current meteo
Not a good option
UNIPAD Contribution 10
Main results point A: occurrence of Debris flows-current climate
Meso scale climate variables only
- Pseudo homogeneization of RTM data to reduce mistakes in the database
- Analyze from 1970
No data or year without debris flows ?
Main results point A: occurrence of Debris flows-current climate
Meso scale climate variables only
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Df occurrence
Precipitation (Number
of rainy days)
Temperature
(maximum summer
temperature)
UNIPAD Contribution 12
Main results point A: occurrence of Debris flows- current climate
Debris flow probability=
1 / (1 + EXP((30,23+1*Tx+0,67*Nrd)))
Meteo factors Value Wald Chi-Square Pr > Chi² % correct 0 % correct 1 % correct
Tx 1,064 5,089 0,024 72,47% 72,31% 72%%
Nrd 0,671 3,066 0,008
Main results point A: DF and landslides activity Local scale
DF and shallow landslides triggered by extreme precipitations
Meso scale
DF and shallow landslides triggered by Temperature + precipitation
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Main results point A: Meso scale : climate + geomorphic parameters
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Regional component
(climate variables at annual scale)
Individual component
(catchments characteristics)
Binary probability
for a catchment i for a year t
Statistical modeling: bayesian hierarchical probabilistic model based on logistic regression
logit (pit) = a0 + αi + βt
Main results point A meso scale
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Individual component
• Elevation
• Area
• Slope
• Lithology
• Land cover
• Permafrost
Regional component
• Number of rainy
days
• Daily max
temperature
• P>10mm/d
• P>20mm/d
• …..
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Geomorphological
component (R² 0.78) Climatic component
(R² 0.72)
Total explained variance: 0.84
% of total variance 0.29
1- Permafrost 80%
2- Surface area 13%
3- Forest (land cover) 7%
% of total variance 0.55
1- max T in summer 67%
2- Nb of rainy days 33%
Main results point A (meso scale): Role of climatic and geomorphic variables in DF triggerring
Point D: Consequences on transportation network
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A. Consequences on
transportation network
The 4th of june 2012 a DF event destroyed the road close to Lautaret pass
Method: point D (Impacts of DF/landslides activity on road network)
DF impact databases in the three regions
A comparative analysis in normal and disturbed situation of the network (Accessibility : distance and time)
Susceptibility of the network considering future DF probabilities
Crisis management analysis (In France only)
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Impacts on transportation: Swiss Alps
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Loss of accessibility in Zermatt valley
125 DF events since the19th century
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(>7events/year) = 1/(1+exp (-(-
21,91+0,14*Nrd+0,9Tx)))
Impacts on transportation French Alps
Identification of impacted roads
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(>7events/year) = 1/(1+exp (-(-
21,91+0,14*Nrd+0,9Tx)))
Main results point D
Loss of accessibility with national and international impacts
The 4th of June 2012 a DF event
destroyed the road close to Lautaret
pass
IT1 : Normal situation
IT2 : Via Gap
IT3 : Via St Jean de
Maurienne
Grenoble-Briançon options.
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Normal way
Road destroyed by the DF event
2 solutions
+ 1h30; 36€
+ 1h10; 66€
NCAR/ASP Thompson Lecture Series
Institutionnal vulnerability : crisis management.
Reconstitution of decision-making and organizational process :
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Impacts on transportation: Italy
Identification of impacted roads with local stakeholders (Tyrol region)
Probability of dysfonction in the future
Point C: Definition of RCMs future scenarios
All simulations are based on the A1B emission scenario
24 RCMs until 2050 and 17 RCMs until 2100 from the EU-FP6 project ENSEMBLES.
Error correction.
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Main results point C: error corrections
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Raw (orange) and corrected (blue) precipitation distributions
at station St. Valent (Tirol). Left: Light and moderate
precipitation; Right: Heavy precipitation.
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after Météo-France, 2011
Near future (2020-2050)) Far future (2070-2100) Annual precipitation sum changes
Annual maximum temperature changes
+2°C +4°C
slightly more slightly less
Main results point C
Future climate change
Main results point C: Triggering climate parameters in the future
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Climate change signal of precipitation types . The number of stations with increasing (arrow up),
decreasing (arrow down), and no change (horizontal arrow (-1 % to +1 %)) for precipitation
frequency of different thresholds is shown. Different colors represent the numbers of stations.
Main objectives
A. Document current DF/shallow landslide activity in the Alps
B. Consequences on transportation network
C. Definition of RCM future climate scenarios
D. DF response considering future climate conditions and lande use planning
E. Help to practical users
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Point D local scale: Results
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Current period Future period
Model of DF triggering based on Rcms data
24 RCMs until 2050
17 RCMs until 2100
A1B scenario Model of DF triggering forced by future climate scenarios
2100
2050
Point D meso scale: Results
Model of DF triggering calibrated on Safran data
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Current period
Future period
Interchanging Safran with RCMs downscaled data
Model of DF triggering based on Rcms data
24 RCMs until 2050
17 RCMs until 2100
A1B scenario
Model of DF triggering forced by future climate scenarios
Step 1 Step 2
Step 3
Point E: Help to practical users
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1. Volume and run out estimates from MassMov2D
(physical model) for case studies
2. Crisis amanagment analysis
3. Fonctional disturbance analysis regional and
international scale
In France
In Italy
In Switzerland
1. Volume and run out estimates from MassMov2D (physical
model) for case studies
2. Probability of future dysfonction based on climate scenarios
for cases studies
1. Fonctional disturbance analysis regional and international scale
2. Technical investigations
From a case study example: The rif Blanc df event on 4th of June 2012 Volume and run out estimates from a deterministic model
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Volume estimated from peak flow calculation :
(from the video of the 2nd DF at 10am)
1. Number of pictures per second on
the video (30p/sec).
2. Section of the flow
(L x h x WP).
3. Choose a representative block
(B). transported distance/ time
between :
Position 1 at the time T
Position 2 at the time T+1
4. Qp = WS (m²) x velocity (m/s)
5. Rickenmann volume estimation :
Qp = 0.1V0.83
V = 10 760
Debris flow volume (2nd)
= 11 000m3
Help to local stakeholders
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Sensitivity tests of local protections to DF on the Highway France-Italy
<15 year return period <30 year return period
Sensitivity to climate change of the debris flows which are able to reach the road system along the considered road
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Help to local stakeholders in italy
Summer
Fall
Conclusions
Current relationships between DF/landslides and climate depends on the considered region
Slope processes strongly impact transportation network
Perception of DF Risk depends on the region
Mitigation is not perfect ! (No by pass, underestimation of protected constructions)
Good relationhsip with public stakeholders more difficult with private component
Climate would have a stronger influence than geomorphic component on DF activity
Future climate change will impact slope processes but how? More data are needed to clarify change in Frequency/ magnitude
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