concept of flood risk (1)

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


Hazard is a potential for harm, loss or damage. Hazard exists wherever land is liable to flooding.Hazard increases with probability and depth of inundation, and with velocity of flow.


Hazard is a potential for harm, loss or damage.

Hazard exists wherever land is liable to flooding.

Hazard increases with probability and depth of inundation, and with velocity of flow.

VISTULA RIVER, POLAND


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


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


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

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

STRUCTURAL NON-STRUCTURAL

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.


NOTE ABOUT Exposure to Flood Hazard

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

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)

INSTITUTIONAL FOUNDATION

LEGISLATION

POLICY

ORGANIZATIONAL STRUCTURE

INSTITUTIONAL CAPACITY

FUNDING

EDUCATION & PROFESSIONAL

TRAINING


Typically, responsibilities relevant to flood management are fragmented between multiple government agencies. E f f e c t i v e p a r t n e r s h i p

b e t w e e n a g e n c i e s

d i r e c t e d t o w a r d

c o o r d i n a t e d m a n a g e m e n t

o f f l o o d r i s k i s o n e o f

t h e g r e a t e s t i n s t i t u t i o n a l

c h a l l e n g e s .

WROCLAW, POLAND

PLANNING METHODOLOGY

A well structured method is recommended to capture the

strengths of integrated flood management 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.

CO

NSU

LTATIO

N P

RO

CESS

PRELIMINARY PHASE

Identify & Quantify Flood Risk estimate hydrological risk hydraulic model analysis

map existing flood hazard & land use

TECHNICAL ANALYSIS

Identify Alternative Flood Management Options combinations of structural & non-structural measures evaluate future risk consider how to manage residual risk

Appraisal of Impacts economic analysis tangible & intangible social benefits / disbenefits environment – adverse impacts & opportunities

robustness, resilience to future uncertainty

APPRAISAL PHASE

Recommend Preferred Option refine analysis; examine assumptions

document plan

FLOOD MANAGEMENT PLAN

APPROVAL

IMPLEMENTATION

Define Management Objectives collect data

Understand Planning Context population characteristics property & infrastructure institutional arrangements

planning instruments

PLANNING

METHODOLOGY

PLANNING

METHODOLOGY

PLANNING component of the framework

Structured Planning Methodo Definition of management objectives – start with desired

outcomes, not a proposed solution

o Understanding of the planning context – consider pre-existing 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

SUB-BASIN MASTER PLANS

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

PROJECT PLANNING

to mitigate specific flooding problems, either at single or joint local government scale

EXOGENOUS

IMPACTS

SAFEGUARDS & SUSTAINABILITY

Social impacts may be positive or negative, and attention must be directed during planning and design to avoid or mitigate adverse impacts, and enhance beneficial outcomes. In 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

IMPACTS

Safeguards:

Environmental protection safeguards

Location and storage of hazardous materials

Involuntary resettlement social safeguards

Indigenous peoples’ social safeguards

Assessments of the social implications for

gender (women’s issues)

Assessments of social implications for disabled,

infirm or disadvantaged persons

Locations of strategic community services


PLANNING

FLOOD HAZARD

EXPOSURE

VULNERABILITY

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

Land Use Management

flood hazard zoning

land use planning controls

property acquisitions

resettlement

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

River basin master plans

Project proposal planning & appraisal

: risk assessment

: appraisal of alternative options

Planning for emergency response

Planning for post-flood recovery

Urban drainage master plans

Rural drainage master plans

Partnerships: across levels of government Restructuring: enhancing coordination

between different levels of government

Legislation: clarifying mandates Training / awareness / capacity building

ENVIRONMENTAL

SAFEGUARDSSOCIAL

SAFEGUARDS

GENDER

ISSUES

INDIGENOUS

PEOPLES’

SAFEGUARDS

COMMUNITY CONSULTATION

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

There is the strategic framework for flood risk management.

A sound institutional foundation is of crucial importance.

THANK YOU

THE END

MANILA, PHILIPPINES

concept of flood risk (1)

Education