Download - The use of evacuation and loss of life models to improve flood incident management in the UK
The use of evacuation and loss of life models to improve
flood incident management in the UK
Darren Lumbroso, Manuela Di Mauro and Andy Tagg
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Flood incident management in the UK
Flood warning and emergency
response
Flood detection
Flood forecasting and interpretation
Flood warning dissemination
The role of loss of life and evacuation modelling to support and improve flood incident management
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Issue with emergency planning for floods in UK
• Lack of communication to general public
• Identification of evacuation routes and safe havens
• Vulnerable groups (e.g. the elderly) and areas (e.g. caravan sites) are often not identified
• Limited risk assessments for dam breaches and flood defence failures in terms of loss of life and evacuation
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Supporting incident managementLoss of life and evacuation modelling
Time to evacuate
Loss of life, and how its affected by:Road closuresWarning disseminationUse of safe havensAwareness
Quantified reporting, number of:Fatalities and injuriesVehicles swept awayBuildings destroyed
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Levels of modelling - Micro
Detailed representationof evacuationroutes
Behaviour of each individualis modelled
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Levels of modelling - Meso
Simplified evacuationroutes
Mortality rates estimatedfor groups of people or zones
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Levels of modelling - Macro
Evacuation timebased on averagedistanceto safety
One mortality rate applied to the wholearea
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Typical scale of application?
Regional/Broad scale study/Lower risk
Small area/Detailed study/High risk
Micro
Meso
Macro
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Micro scale - BC Hydro Life Safety Model (LSM)
• Allows dynamic interaction between receptors (i.e. people, vehicles and buildings) and the flood wave
• Estimates loss of life from:- Drowning- Exhaustion- Building collapse- Cars being swept away
• Allows the effects of interventions (e.g. road closures, number and location of safe havens) on the evacuation time and risk to people to be assessed
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Life Safety and Evacuation Model
2D flood Modelling
Virtual world- People
- Properties- Vehicles
(Time and space distributed)
Life safety simulator- Loss of life/Injuries
- Routing of people and vehicles(i.e. physical equations and logic)
Results and visualisation-Loss of life
- Injuries- Building collapse- Evacuation time
Overview of the LSM modelling process
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BC Hydro LSM – Creation of a virtual world
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Readily available data in the UK
• Population data from census
• Number of vehicles from census
• Topographic data
• Flood depths and velocities from two dimensional hydraulic model
• Property data from a geo-reference National Property Data set
• Road network data
• Historical data (e.g. 1953 flood)
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Thames Estuary - Pilot sites
Thames Barrier
Canvey Islandpilot site
0 5 10 15 20 km
NKent
Essex
Administrative boundary
Thames Estuary
0 5 10 15 20 km
Greater London
NKent
Essex
Thames Estuary
Thames Barrier
Canvey Island
Thamesmead
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Thamesmead - Background
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Thamesmead
River Thames
Boundary of Thamesmead embayment
River Thames
Boundary of Thamesmead embayment
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Thamesmead – Modelled scenarios
• A range of important inundation scenarios modelled
• Varied number of safe havens
• Varied number of road closures
• Difference in warning rates and number of warning centres
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Thamesmead – Modelled scenarios
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Evaluation of different scenarios - Safe havens
Percentage of people that reach a safe haven analysed for different time steps and for different numbers and locations of safe havens
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8
Time (hours)
Pe
rce
nta
ge
of
pe
op
le r
each
ing
saf
ety
(%
)
4 safe havens
6 safe havens
8 safe havens
10 safe havens10 safe havens
4 safe havens
6 safe havens
8 safe havens
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Effect of road closures
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Effect of road closures on evacuation and loss of life
Una
ware
Aw
are
Aw
are
&E
vacuat
ing
Saf
e
Top
pled
Dec
ease
d
No Road Closed1 Road Closed2 Roads Closed3 Roads Closed
1
10
100
1000
10000
100000
Peo
ple
[L
og
]Consequence on People in Roads ClosingEffect of road closures on people
Increase in fatalitiesfrom 6 to 12
Increase in peopleknocked overfrom 15 to 200
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Canvey Island
River Thames
Boundary of Thamesmead embayment
River Thames
Boundary of Canvey Island
River Thames
Boundary of Thamesmead embayment
River Thames
Boundary of Canvey Island
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Canvey Island – Flood map
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Canvey Island - Background
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Maintenance of flood defences
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Results for the modelled scenarios
• Approximately 37,000 people at risk on Canvey Island
• Approximately 15,500 buildings
• For design event between 350 and 400 fatalities (approximately 1% of the exposed population)
• Up to 2,000 buildings destroyed
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Canvey Island – properties
19532001
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Canvey Island 1953 flood
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Results of 1953 modelling
• Results agree well with historical data
• Modelling indicates 55 to 155 fatalities
• Number of buildings destroyed similar to that available from anecdotal evidence
• Around 55 fatalities as the result of drowning and 0 to 100 as the result of exhaustion
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Use of the Life Safety Model • Risk assessments for dams
• To inform emergency management plans• To assess loss of life and injuries in a transparent manner from a variety of causes:
- Drowning- Exhaustion- Building collapse- Cars being swept away
• To provide another measure of risk to assist in decisions related to the construction and maintenance of new and existing flood defence assets
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Conclusions
• Provides a more scientifically robust method for estimating loss of life than other methods previously used in the UK
• Could be used to improve emergency plans for heavily defended areas (e.g. London, some coastal areas) and dam risk assessments in the UK
• In future could be adapted to incorporate risks from other hazards e.g. toxic spills, nuclear accidents
• The LSM provides an evacuation modelling and loss of life tool that is sufficiently mature to support emergency planning and incident management
Any questions?