ESPACE: Decision Testing Framework Thames Pilot Study

Tim Reeder & Bill Donovan, Environment AgencyJon Wicks, Halcrow

Structure of talk� Challenges of flood risk management in the

Thames Estuary� UKCIP decision making framework� Application of the framework to the Thames

Estuary

The Thames Estuary� 1.25 million people £80bn property at risk � Ageing defence infrastructure� Increased development pressure

� 160,000 new homes – most in protected floodplain� Impacts of climate change include

� Southend max level (say +1m 2050, +2m 2100)� Fluvial flows, +20%? to 2050

200 years of Rising Sea Levels at Canvey Island

The same building in 2002: the defences, raised following the 1953 flood and raised further in the 1980s are now level with the roof eaves

The Lobster Smack in 1902: the defences were described at the time as being “practically invulnerable”

??? 2100 defences

The future view for London?

1879 Flood Act >>

Late C19 update to Flood Act >

1928 Flood & subsequent 1930 Flood Act >>Interim Defences during the construction of the Thames Barrier >>

Thames Estuary 2100 Project� Aim:

� Develop a flood risk management plan for London and the Thames Estuary for next 100 years

� Addressing:� Management of estuary from a risk

perspective and a ‘whole society’ approach

• At Risk• The Current Defences

• 1.25million people - 400 Schools, 16 Hospitals• £80bn Property - 30 Mainline Railway Stns• International Habitats & Species - 68 Underground & DLR Stns• Port of London generates £2.7bn/yr. - 8 Power Stations

Thames Barrier

• Climate change will increase the risk• Future Scenarios

• Control structures/walls• Flood water storage

337kms of Defences

• Adapting behaviour & expectation• Flood event management

FORESIGHT FUTURES

• World Markets

• National Enterprise

• Global Sustainability

• Local Stewardship

Possible Responses

Thames Estuary 2100 Project� To achieve the project objectives we have

based our programme of studies around the UKCIP Decision-Making Framework…

� Helps deliver policies and projects that are robust in the face of an uncertain future climate

www.ukcip.org.uk

Eight-stage decision-making framework

The decision-making framework:� Directs you to undertake rapid risk

characterisation and screening exercises before deciding to spend more time/money on more detailed risk assessment

� Helps you refine the problem and objectives and modify your options before making a decision

� Guides you to review a decision

Application to Thames Estuary� Currently in

steps 2 to 5

2 Establish decision-making criteria

3 Assess risk

4 Identify options

5 Appraise options

� Expect 3 iterations:� High level economic appraisal

(strategic options)� Early conceptual options� High level options

� Leading to Thames Estuary Flood Risk Management Plan

� Further work to implementation.

Steps 2 to 5 iteration

2 Establish decision-making criteria

3 Assess risk

4 Identify options

5 Appraise options

� Detail increases with each iteration, as:� Better data become available� Decision-making criteria

become better established� Increased stakeholder

involvement� But basic decision-making

framework (and many underlying tools) remain the same.

Steps 2 to 5 iteration

Define appropriate risk analysis framework

Define appropriate cost benefit calculation framework

Estimate costs of interventions

Consequential losses

Short uncertainty analysis

MDSF analysis: test strategic options under climate change scenarios (2000, 2050, 2100) => AAD Broadscale ISIS-

TUFLOW simulation to generate flood

depth gridsMDSF Economic direct flood damages analysis

MDSF Social impact analysis

Repeat for each scenario

Export MDSF results

Estimate of flood fatalities

Analysis and reporting

Short social / environmental analysis

High level economic appraisal

Databases MDSF Customised GIS & Database

Data: Background maps Existing flood maps DEM Property data Land use Environmental Coastline Etc Local Data: Local reports Etc

Outputs

(electronic plans?)

General Features: Import & store data Case/scenario management Metadata Generate views

Coastal Erosion: Import erosion contours

Flood Mapping: Import water levels Generate (or import) flood depth grids

Economic Analysis: Flood damages Erosion damages

Social Impacts: People affected Social flood vulnerability

Policy Evaluation: Compare baseline with scenarios

Uncertainty Estimation: Acknowledge and estimate uncertainty

Case Definition: Climate Land use Policy

Further analysis, iteration, consultation and review leading to:

CFMP / SMP

Strategy Plan

MDSF - System Overview

External ‘tools’ to provide: (1) flood

depths (optionally extents)

(2) erosion

contours

Repeat for all ‘cases’

ISIS-TUFLOW broad scale flood model

� Could show 10m tuflow – greenwich?� Shows use of same tools at greater detail

Findings� 4 strategic options tested:

� 1 - Do nothing (walk away & leave barriers open)� 2 - Maintenance only – declining standards� 3 - Do ‘something’ A giving 1:1000 protection� 4 - Do ‘something’ B giving 1:5000 protection

� Analysis shows high benefit/cost ratios for 2, 3 & 4� But not sufficient ‘detail’ to:

� Select best strategic option� Understand benefits of spatially varying standard

� And no information on actual interventions

Currently working on further iterations� High level economic

appraisal (strategic options)

� Early conceptual options

� High level options

Stakeholder engagement� Send results to FloodRanger

� More text here

FloodRanger & FloodRanger Pro

Conclusions – to be written� UKCIP - Good framework –generic� Need tools to assess risk� MDSF – � FloodRanger - � Range of details, both spatial and data� But can use same basic framework and tools� Plug for uncertainty analysis to drive where to

go into more detail

Thank you