Foresight future floding Ian Meadowcroft, Environment Agency JimHall

Foresight future flodingIan Meadowcroft, Environment Agency

JimHall

University of Bristol, Department of Civil Engineering

Paul Sayers, HR Wallingford

Aim of the project

• Use best available science to provide a vision

for flood and coastal defence, 2030 - 2100

• Independent look

• Broad scope

• Sustainability analysis - economic, social and

environmental consequences

Project stages

• Phase 1 - Conceptual model, drivers and

responses

• Phase 2 - Impacts (assuming no change in

current policy)

• Phase 3 - Responses

• Reporting / hand over

Overview of approach - The flooding system

Conceptual risk model

• Probability and consequences

• Source - Pathway - Receptor

• Recognise a wide range of drivers and responses

• Holistic risk model ‘glued’ the team together - over

60 experts involved in providing information and data

• Also enabled integrated analysis of river, coastal and

urban flooding

Overview of approach to risk

.

System descriptorsPathways

beaches, flood defences,

urban surfacesfields,

floodplains

Receptorspeoplehouses

industriesinfrastructure

ecosystems

Sourcesrainfall

sea levelmarine storms

etc.

Risk

economic, risk to life, social, natural environment etc

System analysis

Drivers (Phase 2)Processes that change the state of the

systemChange in risk

Responses (Phase 3)Interventions that modify the behaviour of

the system

Change in risk

Portfolios for catchment-scaleflood-risk management

Common menu of responses implemented under the four scenarios

Low regulation and limited emphasis on the

environment. Piecemeal engineering measures to reduce risk, centrally-

managed with limited local capabilities

National wealth does not keep pace with increasing

risk. Abandonment of fluvial and coastal floodplains. Reinstatement of natural

systems. Diversity of approaches across UK

regions

Free market provision of measures to reduce impacts of flooding and hedge risks. Major engineering measures to keep pace with increasing

risk.

Strategic regulation of development, management of runoff and reduction of

impacts. Strategic soft engineering of rivers and

coasts. Universal protection through public-

private schemes

Developing scenarios of future flood risk reduction policies

Summary of Expected Annual Damage from the baseline analysis of flood risk

Present dayWorld Markets 2080s

National Enterprise 2080s

Local Stewardship 2080s

Global Sustainability 2080s

Total flood risks (£ billions) 1.2 28.6 20.2 2.3 6.8

GDP (£ billions) 1,070 15,100 4,910 2,780 8,630

Growth in GDP relative to present day

1.0 14.1 4.6 2.6 8.1

EAD as a percentage of GDP 0.13% 0.19% 0.41% 0.08% 0.08%

Scenarios of engineering responses World markets National

enterpriseLocal stewardship

Global sustainability

Flood/coastal defences (embankments)

High standard hard defences to protect areas of high economic value

Reliance on hard defences to protect areas of high economic value

Retreat and abandonment. Defences to protect urban areas.

Towards soft defences. High tech monitoring and control of soft systems

Storage/detention (rural)

Major strategic storage systems and flood relief channels. High tech control.

Some storage schemes

Restoration of natural floodplain functions. Limited engineering control.

Major strategic storage systems and flood relief channels. High tech control.

River management

River management to maximise conveyance.

River management to maximise conveyance

Widespread restoration of natural river systems

Multi-use river management for conveyance and environment

Coastal management

Collapse of some schemes. New hard defences in high value areas. Measures to improve amenity, mainly privately-funded.

Piecemeal approaches to coastal management result in continued reduction in sediment supply to beaches.

Natural coastal processes reinstated.

Strategic coastal management, regionally and nationally coordinated Some improvement in sediment supply to beaches.

Managed retreat In areas of abandoned agricultural production

Parochial pressures limit opportunities for managed retreat

Regionally diverse. Some reinstatement of natural processes.

Strategic managed retreat in rural and some coastal areas

World markets

National enterprise

Local stewardship


Managed retreat

In areas of abandoned agricultural production

Parochial pressures limit opportunities for managed retreat

Regionally diverse. Some reinstatement of natural processes.

Strategic managed retreat in rural and some coastal areas

World markets

National enterprise

Local stewardship


Flood/coastal defences (embankments)

High standard hard defences to protect areas of high economic value

Reliance on hard defences to protect areas of high economic value

Retreat and abandonment. Defences to protect urban areas.

Towards soft defences. High tech monitoring and control of soft systems

Quantified analysis of theresponse portfolios

Realignment of Flood Defence Infrastructure + + ++

+++

Wales

Midlands

East Anglia

North-east

South-west

Thames

North-west

South-east

IFM as percentage of 10km x 10km grid cell<1%1 - 5%5 - 20%20 - 50%> 50% Drawing numberJob number

Date

Percentage of Indicative Flood Plainper 10km x 10km grid cell

Revision

Foresight - Future Flood Risks

June 2003 1.01

CDS 0438

0 50 10025Kilometres±

This map is reproduced from Ordnance Survey materialwith the permission of Ordnance Survey on behalf ofthe controller of Her Majesty's Stationary Office.(c) Crown Copyright. Unauthorised reproductioninfringes Crown Copyright and may lead to prosecutionor civil proceedings.Department of Trade and Industry. 100037208. 2003.

IFM as percentage of 10km x 10km grid cell<1%1 - 5%5 - 20%20 - 50%> 50% Drawing numberJob number

Date

Percentage of Indicative Flood Plainper 10km x 10km grid cell

Revision


June 2003 1.01

CDS 0438

0 50 10025Kilometres±


Distribution of the Indicative Flood Plain (2002)

Wales

Midlands

East Anglia

North-east

South-west

Thames

North-west

South-east

Dominant valley classcoastallowland (intermediate / shallow valley slopes)upland (steep valley slopesno defences

Drawing numberJob number

Date

Dominant Valley Class

Revision


June 2003 1.01

CDS 0438

0 40 8020Kilometres ±


Dominant valley classcoastallowland (intermediate / shallow valley slopes)upland (steep valley slopesno defences

Drawing numberJob number

Date

Dominant Valley Class

Revision


June 2003 1.01

CDS 0438

0 40 8020Kilometres ±


Dominant Valley Class (2002)

Results of quantified risk analysis

• Results are presented using six risk metrics

– Number of people living within the floodplain.

– Annual probability of flooding.

– Number of people at high risk of flooding.

– Expected Annual Damage (residential and commercial properties).

– Expected Annual Damage (agricultural).

– Social flood vulnerability.

No. of people within Indicative Flood Plain

Probability of inundation - 2080s

Emphasis on “defence” and reducing flood probability

Emphasis on “managing” probability and impacts

Probability of inundation - 2080s

No. of people living with a high probability of being flooded - 2080s

Expected Annual Damage (Property) - 2080s

2002

2080sWorld Markets

2080sGlobal Sustainability

2080sLocal Stewardship

2080sNational Enterprise

Present day (2002)

2080s Foresight Scenarios

Key

Change from present day (2002)Negligible (-£1k to £1k)Low increase (£1k to £100k)Medium increase (£100k to £10,000k)High increase (>£10,000k)Decrease (<-£1k)Outside IFP

N

Feb 2004

0 100 200 km

Expected Annual Economic DamageNegligible (< £25k)Low (£25k to 250k)Medium (£250k to £2,500k)High (>£2,500k)Outside IFP

Comparative Risk - Expected Annual Economic Damage(residential & commercial property)

Expected Annual Damage (Property) - 2080s

Analysis of implementation costs

Aim:• To provide an indication of the

relative costs of implementation under each scenario

Example - under GS scenario:• Using engineering only: Cost £52

billion• Using engineering and non-

engineering: Cost £22 billion

Results of investment cost analysis

Note:

– Only the costs of engineering measures have been estimated (excluding non-structural interventions)

– Exclude land purchase, compensation or significant environmental mitigation

– Typical costs based on the Environment Agency national cost database

Sensitivity analysis - High growth / low emissions scenario

Conclusions

• These are not the only flood risk management portfolios that would be consistent with the four future scenarios

• Major flood risk reduction is achievable under all scenarios

• Non-structural measures can make a major contribution to reducing the need for (and hence costs and impacts of) engineered flood defences.

• Achieving a low emissions future could reduce flood risk by 25% assuming a high growth economy is maintained - a significant contribution to reducing flood risk but not a panacea.

Big messages

• Continuing with existing messages is not an option

• Should we accept increasing risk, seek to maintain present risk, seek to reduce the risk?

• Risks need to be tackled across a broad front:

– Sustainable responses, particularly increased investment in defences, catchment-wide storage, land use planning and realigning coastal defences

– Reduce global emissions

– Need to develop science, skills and governance issues

• Action Plan published and the baton passed to Defra, EA and others.

Finally...

• The project combined a new paradigm for combining cutting-edge science and futures analysis to inform policy.

• Information at www.foresight.gov.uk

• Reports available from DTI Publications:

– Executive Summary

– Action Plan

– Volume 1 and 2 technical reports

Documents

Foresight future floding Ian Meadowcroft, Environment Agency JimHall