natural hazards - flood response planning
TRANSCRIPT
Emergency planning andmanagement of the
flood hazard
Emergency planning andmanagement of the
flood hazard
Prof. David AlexanderGlobal Risk Forum Davos
Structure of lesson:-
• general observations on emergency planning
• emergency planning for floods
• perception of flood hazards
• management of flood emergencies
• conclusions
Planning to manageflood emergencies:
general observations
QU
AN
TIT
Y
TIME
needs
local self-help
imported assistance
unmet needsReduce unmet needsReduce unmet needs
Increase local self-sufficiencyIncrease local self-sufficiency
Rationalise imported assistanceand make it more timely
Rationalise imported assistanceand make it more timely
The challenges of emergency planning
Emergency planning:single hazard or all hazards?
Modern emergency planning is genericin that it should tackle all probable
hazards that threaten the area of itsjurisdiction, with specific chapters
on managing individual risks
Planning to tackle all known risksis more efficient than planning
for single hazards.
Some relevant concepts ofemergency planning:-
• microzonation of hazards and risks
• economic and urban development only with risk reduction measures
• evaluation of consequences of impacts and secondary hazards.
Importance of risk andhazard microzonation
microzonation is costly,often difficult to get approved,
but essential toaccurate risk planning
The emergency plan should be...
• generic: adaptable to many risks
• a process, not merely an end in itself
• flexible and constantly updated
• based on ample research on scenarios of hazard, risk, etc.
• composed of a synthesis, general lineaments and detailed appendixes.
GeneralisedGeneralised DetailedDetailed
Synthesis:abbreviated
plan
Synthesis:abbreviated
plan
Details:data,
annexes,appendices
Details:data,
annexes,appendices
Plan:structure
Plan:structure
"Architecture" of an emergency plan
HAZARD
VULNERABILITY
IMPACT RISK
RESPONSE
MITIGATION
HYPOTHETICAL
SCENARIOS
Every elementof the emergency can be modelled
with scenario methodology
consequencesat time 2
consequencesat time 2
evolutionevolution
consequencesat time 1
consequencesat time 1
formal evaluation of theoutcome of the scenarioformal evaluation of theoutcome of the scenario
evaluation ofthe progress
of the scenario
evaluation ofthe progress
of the scenario
develop- ment of the scenario
develop- ment of the scenarioconsequences
at time nconsequences
at time n
evolutionevolution
initialconditions
initialconditions
historicalanalysis
historicalanalysis
hypotheticalingredients
hypotheticalingredients
referenceevent
referenceevent
timezerotimezero
Scenariomethodology
Scenariomethodology
Emergency Planning
SMALL SMALL
LARGE
Physicalimpact
Physicalimpact
Humanconsequences
Humanconsequences
chain of consequences
chain of consequences
LARGE
• from the paper planning syndrome to the digital equivalent
• a possible dependence on methods and equipment that might not function.
• the most publicised product wins!
• dissemination of low-quality information
• there is no guarantee that the digital product will be used more rationally than the traditional paper equivalent
Some syndromes to avoid:-
The solution...
• estimate costs and benefits of project
• plan a sustainable system that has robustness and redundancy
• develop its "user-friendliness"
• use well-tested procedures.
Planning should berelevant to all ormost phases of the'disaster cycle',not only theemergencyresponse phase
Elementsof planningfor floodemergencies
LEGALAUTHORITIESnational, state,
regional, provincialand municipalgovernments,
privatelandowners
PHYSICALSYSTEM
floodplains,watersheds,
wetlands,coasts, etc.
LAND USEforms of
investment anddevelopment in
floodplains
Protective actionsstructural projects
laws and codeslegal decisions
insurance schemesalarm systems
civil protection services
Socioeconomicdata
Hazards and environmental perception Hazards
and risks
Environmentalimpacts
A MODEL OFRESPONSES TOFLOOD RISKS
The range of possible flood mitigationmeasures - structural solutions:-
Risk abatement, for example• management of snow cover• management of urban hydrology• consolidation of river banks and beds
Flood protection for example, levées and walls, drainage channels, river diversion schemes.
Effect of urbanisationon flood propensity
Dis
ch
arg
e,
Q
Time, t
input of water tourban drainage basin
(rapid rise,shortened warning)
input of waterto rural drainage basin
urban transformation of discharge rates
Flash flooding:Flash flooding:
• quantity (mm) and duration (hrs) of the rainfall event
• intensity (mm/hr) of rainfall
• infiltration rate and capacity for local land surfaces (mm/hr)
• in flash floods rainfall rate exceeds infiltration capacity, giving rise to rapid increases in discharge.
Particular risks are associated with
urban areas located on alluvial fans
The range of possible flood mitigation measures:-
Semi-structural measures, for example• impermeablisation of buildings,• flood storage areas (water meadows)
Non-structural measuresRisk adjustment, for example• flood forecasting• monitoring and warning• evacuation of threatened populations.
Semi-structural measures: temporarybarriers and floodproofing of buildings
The rangeof measures
against flooding
The rangeof measures
against flooding
The rangeof measures
against flooding
The rangeof measures
against flooding
Non-structural measures
Adjustment to the risk, for example• meteorological, hydrological prediction• monitoring and warning• evacuation of threatened populations
Non-structural measures
Adjustment to the risk, for example• meteorological, hydrological prediction• monitoring and warning• evacuation of threatened populations
Administrative definition of the floodplain
Floodplain
Floodway
Height of 100 yr floodHeight of 20 yr flood
Periphery offloodable area
1% probability 5% probability
Mean lowwater level
DEFINITION OF THE FLOODPLAIN IN TERMS OF URBAN PLANNING
"Regulatory floodplain"
River channel
UrbanisationNecessarystructural
modifications
Urbanisation
Floodway
Essential protection level
100-year flood level
Margins offloodable area
Margins offloodable area
Example of anaspect ofemergencyplanning thatis frequentlyneglected:the need for aveterinary plan.
Given that floods, acceleratederosion and landslides can occurtogether and result in a complexof problems for road access and
the stability of buildings....
...plans should be made on thebasis of hazard and risk scenarios
which include the entire rangeof predictable effects:• flooding levels, and• erosion potential.
NATIONALEMERGENCY PLAN
REGIONAL ANDCOUNTY ORPROVINCIALEMERGENCY
PLANS
MUNICIPALEMERGENCY
PLAN
MUTUALASSISTANCE
PACTS
AIRPORT ANDTRANSPORTEMERGENCY
PLANS
HOSPITALAND HEALTH
SYSTEMEMERGENCY
PLAN
INDUSTRIALAND
COMMERCIALEMERGENCY
PLANS
CULTURALHERITAGE
EMERGENCYPLAN
Floods, landslides, storms- all hazards...
informationflows
informationflows
volunteersvolunteers press office ofC.P. service
press office ofC.P. service
Civil protection services
Civil protection services
Emergency
managers
Generalpublic
Specialgroups
At riskgroups
Mass media
Journalists
Pool of accredit
ed journalis
ts
publicitycampaignspublicity
campaigns
interviews &information
interviews &information
fieldexercises
fieldexercises
Floods do not respect political boundaries
There is a particular needfor mutual aid agreements
Flood perception
Hazard, risk and disasterpercetion is a factor that:-
• limits the potential of emergency planning and management
• offers opportunities to create plans tailored to the needs of users
Good emergency planning and managementtakes perception factors
seriously into consideration.
1,200 questionnaires were administered to victims of the 1999 Red River floods (USA/Canada):
• 95% of residents knew of the existence of flood insurance
• 20% had purchased the insurance.
An example...
The main reasons for buyingflood insurance were:-
• 46% lived near a river at risk of flooding
• 53% believed that government hand-outs would not be sufficient
• 89% was worried about the likelihood of flooding.
• after having seen flood maps, 51% thought they did not need insurance
• 75% did not think that floods would damage their properties
• 80% underestimated the risk and did not believe floods would happen.
The main reasons for not buyingflood insurance were:-
The lessons of this example:-the motives for not taking advantage ofthe protection offered (flood insurance)were complex, but until disaster struck there was aconsistent tendency to understimate the risk.
The lessons of this example:-the motives for not taking advantage ofthe protection offered (flood insurance)were complex, but until disaster struck there was aconsistent tendency to understimate the risk.
Warninginformation
Other newsof imminent
disaster
THE SOCIAL PROCESS OF EVACUATION
Confirm,verify,decide
REMAIN IMPACT
EVACUATE Choice ofdestinationSocial context
of theresponse tothe warning
Social contextand technology
to warnings
Dis
sem
inati
on
of
info
rmati
on
Acti
vate
th
e d
ecis
ion
Another example:Perceiving the risk means
verifying its existence
When there is a flood:emergency management
On the first day of a typicalemergency, 90% of assistance
to victims will be supplied locally
Therefore, if local resources areinsufficient, so will be the relief operations
supply
demand
timeDisaster
supply
demand
time
urb
an
SA
R shortage
Disaster
shortage reduced byefficient
mobilisation
Summary of medical emergency response
Sprained limbs
LacerationsBruises and similar lesionsOther physical injuries
Sin perforationsAnimal bites
Electric shockUnclassified
Burns
Number of cases
Classification of non-fatal injuriesin the 1993 Missouri River flood (USA)
EMERGENCY REQUIREMENTSGENERATED BY FLOOD DISASTERS
IMPACT
MASSEVACUATION
PUBLICHEALTH
MONITORINGAND CONTROL
OF DISEASES
INJURIESAND MEDICAL
ASSISTANCE
FOODDISTRIBUTION
DAYS AFTER IMPACT
MEDICAL ASSISTANCE TO VICTIMS
WATER SUPPLY TO PRIORITY GROUPS
PUBLIC HEALTHMEASURES
EPIDEMIOLOGY
Out
erco
rdon
Inner cordon
MASS CASUALTYINCIDENT
MASS CASUALTYINCIDENT
Helicopterambulance
Secondarystaging
area
Minorinjuries
treatment
Massmediapost
Incidentcommand
post
Mortuaryarea
Control postAmbulanceloading area
Triagearea
Ad
van
ce
med
ical p
ost
Primarystaging area
Medical postfor personnel
Rescueloop
Managing the emergency with incident command system
Practical considerations:In flood emergenciesthe private car is:-
Practical considerations:In flood emergenciesthe private car is:-
• a source of mobility and therefore a possible means of evacuation• a source of danger and possible entrapment• a source of road congestion.
Drivers tend tounderestimatethe risksof travelling by carin flood situations.
Practical considerations:In urban areas, rubber boats
can become holed byunderwater obstructions:aluminium boats are more
appropriate in flood situations.
Conclusions:-
Emergency planning must be:
• multi-hazard
• flexible
• based on accurate zonation
• based on scenarios which anticipate predicable developments
• constantly updated.
Conclusions:-
Management of flood emergencies:
• public perception of risks needs to be constantly monitored
• local resources must be used in the most efficient and timely manner
• mobility and traffic circulation are particularly problematic.
Floods tend to be repetitive events,in many cases with quite short
recurrence intervals (return periods).
This does not prohibit the occurrenceof an event of very high magnitude
and low frequency....
