Flood management in the UK · December 2013 – February 2014 Floods Groundwater flooding, Hambledon, Hampshire, Feb 2014 . Source: Chris Dixon photography . Coastal flooding Cleethorpes

Flood management in the UK

Challenges and responses

Andy Tagg, Floods Group Manager

© 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


Distribution of river floods 1998 to 2009

Image downloaded from

www.eea.europa.eu Copyright EEA

Copenhagen, 2011


http://www.eea.europa.eu/


EU Coastal Flood Damage Potential

Image downloaded from

www.eea.europa.eu Copyright EEA

Copenhagen, 2011


http://www.eea.europa.eu/


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



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



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


© HR Wallingford 2013 Lund, 27th November 2014 Page 8

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.


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)

Page 9 Lund, 27th November 2014


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.


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.


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.


Scale of the challenges – ageing infrastructure

Need a planned lifecycle of: • Maintenance • Repair • Renovation • Renewal Supported by inspection and condition appraisal


Scale of the challenges – extreme events

Managing extreme events: unknown-unknowns. i.e. a combination of circumstances without precedent.


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


Scale of the challenges – urban areas

Dealing with more water in urban areas where urban drainage renewal is not practical. “Blue” routes for water.


Scale of the challenges – health impacts

Health impacts: • Pathogens • Pollutants in flood

waters • Longer term damp

issues • Psychological effects

Flood damage image


Coordination of different agencies

A key criticism in the Pitt Report on the 2007 flood New joint FFS Clear improvement in recent events



Scale of the challenges – flood recovery

Effectively managing the flood recovery and repair process


Scale of the challenges – summary

In summary, encourage: • Awareness • Adaptation • Resilience for a wide

range of stakeholders • Need to identify

resources for the job


FRM - overview


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



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.

Page 23 Lund, 27th November 2014


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)


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



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?



Foresight Project Expected Annual Damage in 2080s



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



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



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


Southend barrier

Defence raising

DP1

DP2

DP3

DP4

DP5

DP6 DP = Decision pipelines (time varying portfolios)

Existing system


Ong

oing

M

aint

enan

ce Southend

barrier Existing system


Ong

oing

M

aint

enan

ce


Time 2008 2050 2100



Risk and adaptability wrapped into MDSF2 tool set



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



Model outputs Risk attribution to defences


© HR Wallingford 2013 © HR Wallingford 2012 Page 34

The reliability tool

© HR Wallingford 2013 © HR Wallingford 2012 Page 35

Defence fragility

Severity of load event

Probability ofdefence failure

0

1.0

0

Standard of protection providedby defence

Fragility curveTypically assumed

“true” fragility


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)



Evacuation modelling



Evacuation modelling

Capacity wasted

Congestion



Theoretical example of dam failure



Loss of life modelling

http://www.lifesafetymodel.net/publications.html


http://www.lifesafetymodel.net/publications.html


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


Dissemination Communication Uptake Implementation

Thank you

[email protected]

Flood management in the UK · December 2013 – February 2014 Floods Groundwater flooding, Hambledon, Hampshire, Feb 2014 . Source: Chris Dixon photography . Coastal flooding Cleethorpes

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