Foresight future floding Ian 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, 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 descriptors Pathways beaches, flood defences, urban surfaces fields, floodplains Receptors people houses industries infrastructure ecosystems Sources rainfall sea level marine storms etc. Risk economic, risk to life, social, natural environment etc System analysis Drivers (Phase 2) Processes that change the state of the system Change in risk Responses (Phase 3) Interventions that modify the behaviour of the system Change in risk

Portfolios for catchment-scale flood-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 day World Markets 2080s National Enterprise 2080s Local Stewardship 2080s Global Sustainability 2080s Total flood risks (£ billions) GDP (£ billions) 1,07015,1004,9102,7808,630 Growth in GDP relative to present day EAD as a percentage of GDP 0.13%0.19%0.41%0.08%

Scenarios of engineering responses World marketsNational enterpriseLocal stewardshipGlobal 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 managementRiver management to maximise conveyance. River management to maximise conveyance Widespread restoration of natural river systems Multi-use river management for conveyance and environment Coastal managementCollapse 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 retreatIn 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 marketsNational enterprise Local stewardship Global sustainability Managed retreatIn 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 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

Quantified analysis of the response portfolios Realignment of Flood Defence Infrastructure

Distribution of the Indicative Flood Plain (2002)

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 s Emphasis on “defence” and reducing flood probability Emphasis on “managing” probability and impacts

Probability of inundation s

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

Expected Annual Damage (Property) s

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 Reports available from DTI Publications: –Executive Summary –Action Plan –Volume 1 and 2 technical reports