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transcript
© HR Wallingford 2013
Content
Experiences of flooding (England)
What are the challenges?
Background to flood risk management
What were the responses?
Some examples of approaches/applications
Concluding remarks
Lund, 27th November 2014 Page 2
© HR Wallingford 2013
Distribution of river floods 1998 to 2009
Image downloaded from
www.eea.europa.eu Copyright EEA
Copenhagen, 2011
Lund, 27th November 2014 Page 3
© HR Wallingford 2013
EU Coastal Flood Damage Potential
Image downloaded from
www.eea.europa.eu Copyright EEA
Copenhagen, 2011
Lund, 27th November 2014 Page 4
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Impacts of some European Floods
Damages in € Billion C - Coastal surge, F - Flash flood, P - Lowland Plains flood
Date Countries Location Deaths Evacuees Damage Type
1953 DE,NL,UK
N Sea 2200+ ? ? C
1994 IT River Po 64 10,000 12.5 F,P
1995 DE, NL Rhine 28 200,000? 3.5 P
1997 IT Sarno 160 1210 <0.1 F
1997 CZ, PL Odra 100 200,000 4.5 F,P
2002 CZ, DE Elbe 37 85,000+ 21.1 F,P
2003 FR Rhône 6 27,000 0.7 F
2005 UK Carlisle 0 6,000 0.9 P
2007 UK Midlands 13 40,000+ ~5 F,P
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Some notable floods
Easter 1998 – heavy rainfall across Midlands Winter 2000 Boscastle 2004 – flash flood Carlisle 2005 England 2007 Cockermouth 2009 (1,000 year event) Winter 2013/14
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December 2013 – February 2014 Floods
Groundwater flooding, Hambledon, Hampshire, Feb 2014 Source: Chris Dixon photography
Coastal flooding Cleethorpes seafront, Lincolnshire, Dec 2013
River flooding Tewkesbury and Avon Valley, Jan 2014
Surface water flooding Staines, Jan 2014
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Scale of the challenges - population
Proportion of the population that could be affected by floods but are unaware. A 100-year design standard means major flooding is likely a ‘once in a lifetime’ event for many people.
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Properties at risk
Published originally in 2009
5.2m at risk (now 5.5m)
2.8m surface water only (now 3.9m from SW in total)
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Scale of the challenges - proportion
The proportion of the national assets currently at risk. • Agriculture • Industry • Commerce • Residential The trend is for this to increase.
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Scale of the challenges - public perception
Public perception of flood risk (or the lack of it). Flood Risk Management is a continuous process but only comes into the public consciousness during major flooding.
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Scale of the challenges – flood risk
Possible tension between flood defence and flood risk management. Broadly speaking the public want defences but the policy is for cost effective risk management.
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Scale of the challenges – ageing infrastructure
Need a planned lifecycle of: • Maintenance • Repair • Renovation • Renewal Supported by inspection and condition appraisal
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Scale of the challenges – extreme events
Managing extreme events: unknown-unknowns. i.e. a combination of circumstances without precedent.
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Scale of the challenges – adaptation
Adaptation to impacts, long term trends and variability (and their detection) – precipitation intensity and frequency, wave height and direction, relative mean sea level
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Scale of the challenges – urban areas
Dealing with more water in urban areas where urban drainage renewal is not practical. “Blue” routes for water.
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Scale of the challenges – health impacts
Health impacts: • Pathogens • Pollutants in flood
waters • Longer term damp
issues • Psychological effects
Flood damage image
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Coordination of different agencies
A key criticism in the Pitt Report on the 2007 flood New joint FFS Clear improvement in recent events
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Scale of the challenges – flood recovery
Effectively managing the flood recovery and repair process
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Scale of the challenges – summary
In summary, encourage: • Awareness • Adaptation • Resilience for a wide
range of stakeholders • Need to identify
resources for the job
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Risk Analysis Model
Consequence Damage
s Distress Disease Death Degradation
Receptor
Property People Possessions Environment
Pathway
Bank failure Flood plain flow Sewer surcharging
Source
Rainfall River flow Storm surge Snowmelt
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Flood Risk Management Practice
Post-flood measures
Flood event measures
Real time risk management
Pre-flood measures
Preventive risk management
Forecasting and warning, reservoir control, evacuation, rescue, etc.
Spatial planning, contingency plans, flood
defence (mitigation) measures, insurance, preparedness, etc.
Relief, clean-up, reconstruction,
regeneration, etc.
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RIBAMOD Principles (1997)
Pre-flood measures prevention, protection,
preparedness risk mapping and reduction spatial planning flood defence infrastructure contingency planning
Operational flood management warning and emergency response
Post-flood recovery relief, review, regeneration
FLOODsite (2004 – 2009) Largest EC project on flooding Addressed all aspects of flood risk
analysis and risk management Some approaches piloted for UK
conditions
Environment Agency pilot study (2009 - 2010) Demonstrated several tools for
Humber Estuary (see later slide)
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UK policy development
Foresight future flooding (2002 to 2003)
Making space for water (2004)
EU Directive on the assessment and management of flood risks (2007)
Pitt Review (2008)
Flood and Water Management Act (2010) New responsibilities on Local Authorities Phased implementation in progress Sustainable drainage (SuDS)
Policy is for RISK management not defence
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Risk management
Need to plan with long-term change (what scenarios?) Public acceptance of some degree of risk Need to look at whole system risk
Strengthened spatial planning policy
Focus on Asset Management Flood and Coastal Defence Database (FCDD) register of assets Condition inspection Maintain to achieve performance
Can designs be made “future-proof” to allow adaptation in the future?
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Foresight Project Expected Annual Damage in 2080s
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Decision support
How can good decisions be made?
Long term planning Many scenarios (climate, economic, social, governance) Gross uncertainty
Flood event management Contingency planning Real-time risk management
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Evaluation criteria for long-term planning
Adaptability for however the future pans out
Robustness performance across all future scenarios
Sustainability social, ecological, economic dimensions
Uncertainty future ”gross” and data methods
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Adaptability …
Existing system
Flood storage, retreat
Ong
oing
M
aint
enan
ce
Defence raising & Barrier work
Decision/action point
FRM system state at specific time - Only key new features listed
Defence raising & Barrier work
Southend barrier
Defence raising
DP1
DP2
DP3
DP4
DP5
DP6 DP = Decision pipelines (time varying portfolios)
Existing system
Flood storage, retreat
Ong
oing
M
aint
enan
ce Southend
barrier Existing system
Flood storage, retreat
Ong
oing
M
aint
enan
ce
Defence raising & Barrier work
Time 2008 2050 2100
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Risk and adaptability wrapped into MDSF2 tool set
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Futures and snapshots in MDSF2
Defence raising
2001 2020 2040 2060 2080 2100 Time
Expected Annual Damage
s (£)
Scenario:
Climate change = High
Socio-economic growth = High
Build barrier
Storage based
Do Nothing (reference)
Snapshots
Present day risk
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Defence fragility
Severity of load event
Probability ofdefence failure
0
1.0
0
Standard of protection providedby defence
Fragility curveTypically assumed
“true” fragility
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Flood event management
Integration framework storage, utilisation and visualisation of model results and additional information for emergency management planning and practice.
Implemented via prototype DSS tools. Explore safe escape logistics for secure evacuation in case of disaster • The Life Safety Model (LSM)
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Evacuation modelling
Capacity wasted
Congestion
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Loss of life modelling
http://www.lifesafetymodel.net/publications.html
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So for the future….
The past is not necessarily a good guide Flood events have driven action
Use current best science available for the situation
Engage with uncertainty
Research continues to produce new techniques and tools
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Dissemination Communication Uptake Implementation