A Framework for
Flood Risk Management
An Introduction
Dr John Porter
A good place to start if we want to prepare a
strategic framework for managing flood risk is
to define flood risk.
What is flood risk?
There is no one definition of flood risk, but one that
proves very useful for a strategic framework is
RISK = HAZARD x EXPOSURE x VULNERABILITY
RISK = HAZARD x EXPOSURE x VULNERABILITY
RISK = HAZARD x EXPOSURE x VULNERABILITY
Hazard is a potential for harm, loss or damage.
Hazard exists wherever land
is liable
flooding.for harm, loss or
Hazard
is atopotential
Hazard increases with probability and
depth of inundation, and
damage.
with velocity of flow.
Hazard exists wherever land is liable to
flooding.
Hazard increases with probability and depth
of inundation, and with velocity of flow.
VISTULA RIVER, POLAND
RISK = HAZARD x EXPOSURE x VULNERABILITY
Exposure
Even where a hazard exists,
there is no risk unless there are
assets that can be damaged,
or there is danger because
people live in, work in, or
simply transit through the
location of flood hazard.
Exposure to flood hazard creates
the potential for personal
danger or property damage to
occur during floods.
BRISBANE, AUSTRALIA
RISK = HAZARD x EXPOSURE x VULNERABILITY
The consequences of flooding and therefore the risk also
depends on how vulnerable people and their assets are to danger
and damage.
Vulnerability can be reduced if people and authorities:
take appropriate precautions in advance of flooding,
know what to do to limit danger and damage during floods, and
receive adequate warning and appropriate assistance during and
after floods.
FUZHOU, CHINA
Defining flood risk as
RISK = HAZARD x EXPOSURE x VULNERABILITY
is very useful because the measures we use in flood
management can be regarded as modifying
(reducing) one of these 3 key elements of risk.
MODIFYING HAZARD
Flood control dams
Detention basins
Levees or dikes
Flood diversion channels
River channel
improvements
Upper watershed
management
STRUCTURAL
MODIFYING EXPOSURE
Zoning of land use
Property acquisition
Planning development
controls
Building codes
Flood-proofing buildings
Building on platforms or
stilts
MODIFYING VULNERABILITY
Flood monitoring and warning
Flood forecasting
Emergency response plans
Community awareness
Community preparedness
Post-flood recovery &
reconstruction
Flood insurance
NON-STRUCTURAL
RISK = HAZARD x EXPOSURE x VULNERABILITY
NOTE ABOUT Exposure to Flood Hazard
This involves land management in addition to water
management.
In normal circumstances there is a clear division
between water and land. Water is contained within
rivers, lakes and other water bodies.
During floods, the water regime expands to
temporarily inundate land which most of the time
can be used for productive purposes.
Therefore, unlike other aspects of water resources
management, flood risk management must embrace
both land use management and water
management.
RISK = HAZARD x EXPOSURE x VULNERABILITY
NOTE ABOUT Vulnerability
Many have identified that communities are more vulnerable
to flood risk if there is greater poverty, in
communities with low standards of education,
and in societies with poor governance.
INDUS RIVER, PAKISTAN
RISK = HAZARD x EXPOSURE x VULNERABILITY
Vulnerability or susceptibility
This is true. Programs aimed at reducing poverty and
improving education and political governance will reduce
vulnerability and flood risk. However, we can introduce a
new category for these issues and regard them as issues of
Susceptibility rather than Vulnerability. They are different
because they deal with the ills of society as a whole, are
less specific to flood risk as they affect many other aspects
of community life too. And in that sense, although they are
relevant to management of flood risk, they are not proper
undertakings for flood risk management alone.
Comprehensive flood risk management must
therefore consider treatment of all three elements
of flood risk:
HAZARD
EXPOSURE
VULNERABILITY
Consideration of flood risk as the product of
Hazard x Exposure x Vulnerability
only deals with what we do to manage flood risk.
A strategic framework for flood risk management
must also consider how we organize and how we
plan for management of flood risk.
It should also consider the impacts of what we do
on the environment and the community.
Therefore, other important dimensions of a strategic
management framework are:
INSTITITIONAL FOUNDATION
PLANNING METHODOLOGY or STRUCTURE
EXOGENOUS IMPACTS (social & environmental)
LEGISLATION
POLICY
ORGANIZATIONAL
STRUCTURE
INSTITUTIONAL
CAPACITY
FUNDING
EDUCATION &
PROFESSIONAL
TRAINING
INSTITUTIONAL FOUNDATION
INSTITUTIONAL FOUNDATION
Typically, responsibilities
relevant to flood
management are
fragmented between
multiple government
agencies.
WROCLAW, POLAND
Effective partnership
between agencies
directed toward
coordinated management
of flood risk is one of
the greatest institutional
challenges.
PLANNING METHODOLOGY
A well structured method is recommended to capture the
strengths of integrated flood manage-ment through:
rigorous technical analysis,
comprehensive assessment of planning options,
appraisals based on the triple bottom line of
sustainable development (economic viability, social equity
and environmental acceptability),
benefit-cost analysis and
stakeholder participation.
Define Management Objectives
collect data
PRELIMINARY PHASE
Understand Planning Context
CONSULTATION PROCESS
population characteristics
property & infrastructure
institutional arrangements
planning instruments
Identify & Quantify Flood Risk
estimate hydrological risk
hydraulic model analysis
map existing flood hazard & land use
Identify Alternative Flood Management Options
combinations of structural & non-structural measures
evaluate future risk
consider how to manage residual risk
APPRAISAL PHASE
Appraisal of Impacts
economic analysis
tangible & intangible social benefits / disbenefits
environment adverse impacts & opportunities
robustness, resilience to future uncertainty
Recommend Preferred Option
refine analysis; examine assumptions
document plan
PLANNING
METHODOLOGY
TECHNICAL ANALYSIS
APPROVAL
IMPLEMENTATION
FLOOD
MANAGEMENT PLAN
PLANNING
METHODOLOGY
PLANNING component of the framework
Structured Planning Method
o Definition of management objectives start with desired
outcomes, not a proposed solution
o Understanding of the planning context consider preexisting plans & local factors
o Identification & quantification of flood risk: technical analyses
o Identification & consideration of alternative ways to manage the
flood risk different options comprising packages of FM
measures
o Appraisal of impacts economic, social & environmental benefits
& costs
o Recommendation of a preferred option refinement of solutions;
closer examination of assumptions; documentation
o Stakeholder participation opportunity for consultation at each
step of the process
PLANNING METHODOLOGY
RIVER BASIN MASTER PLANS
PROJECT PLANNING
SUB-BASIN
MASTER PLANS
to mitigate specific
flooding problems,
either at single or joint
local government scale
e.g. - tributaries
- river reaches
(over several local
govt jurisdictions)
- lake / wetland
complexes
URBAN DRAINAGE
MASTER PLANS
for internal drainage
of cities to mitigate
urban flooding
RURAL DRAINAGE
MASTER PLANS
to mitigate
waterlogging of
agricultural land
SAFEGUARDS & SUSTAINABILITY
Social impacts may be positive
or negative, and attention must
EXOGENOUS be directed during planning and
design to avoid or mitigate
adverse impacts, and enhance
beneficial outcomes. In
IMPACTS
particular, impacts on those
displaced or resettled, on
indigenous groups, on the
disabled, aged or infirm, or on
gender groups need to be
examined and assessed.
Environmental impacts may include
unintentional but foreseeable
impacts on the physical
environment, or on the biosphere.
EXOGENOUS Safeguards:
IMPACTS
Environmental protection safeguards
Location and storage of hazardous materials
Involuntary resettlement social safeguards
Indigenous peoples social safeguards
Assessments of the social implications for
gender (womens issues)
Assessments of social implications for disabled,
infirm or disadvantaged persons
Locations of strategic community services
PLANNING
River basin master plans
Project proposal planning & appraisal
: risk assessment
: appraisal of alternative options
FLOOD HAZARD
Flood Control Works
Structural planning & design
Asset maintenance:
monitoring condition
rehabilitation /upgrading
funding
Operations:
decision support systems
communications systems
data acquisition networks
integration with WR management
env.management
Catchment Management
Soil conservation
Upland land use management
Planning for emergency response
Planning for post-flood recovery
Urban drainage master plans
Rural drainage master plans
EXPOSURE
Land Use Management
flood hazard zoning
land use planning controls
property acquisitions
resettlement
VULNERABILITY
Flood forecasting
hydrological models
hydraulic models & DTMs
flood hazard maps
data acquisition networks
Flood warning & emergency response
communications systems
preparedness exercises
decision support systems
Post-flood recovery
support services: health, counseling
material support: food, shelter
infrastructure repairs
financial assistance & incentives
compensation / flood insurance
Land Use Management
building regulations
INSTITUTIONAL FOUNDATION
Partnerships: across levels of government
Restructuring: enhancing coordination
between different levels of government
Legislation: clarifying mandates
Training / awareness / capacity building
ENVIRONMENTAL
SAFEGUARDS
GENDER
ISSUES
COMMUNITY CONSULTATION
SOCIAL
SAFEGUARDS
INDIGENOUS
PEOPLES
SAFEGUARDS
There is the strategic framework for flood risk management.
Key requirements to make it effective are
LEGISLATION THAT CLEARLY DELEGATES ROLES AND
RESPONSIBILITIES
A KEY COORDINATION ROLE MANDATED FOR ONE LEAD
AGENCY IN FLOOD RISK MANAGEMENT (or DISASTER
RISK MANAGEMENT) WITH STRONG POWERS TO
OBLIGE PARTICIPATION BY ALL STAKEHOLDERS IN
JOINT PLANNING
BROADER STAKEHOLDER PARTICIPATION THROUGH
COMMUNITY CONSULTATION DURING THE PLANNING
PROCESS
A sound institutional foundation is of crucial importance.
THANK YOU
THE END
MANILA, PHILIPPINES
