HR Wallingford and Deltares are collaborating to develop an operational flood risk forecasting toolkit within the Delft-FEWS framework. The toolkit will integrate hydrological, hydraulic, breach, inundation and impact models to provide a risk-based approach and probabilistic forecasts. A scoping study is proposed to develop model adaptors, link models, and incorporate risk capabilities. The system aims to provide decision-makers with information on flood hazards, consequences and management actions.

1. October 2014
HR Wallingford Deltares Collaboration
Developing an operational flood-risk-forecasting toolkit
C. Hazlewood, E. Brown, L. Boelee, B. Gouldby, J. Lhomme
A. de Leeuw, F. Diermanse, D. Bachman

2. © HR Wallingford 2014October 2014 Delft-FEWS User Days Page 2
HR Wallingford
Specialise in engineering and
environmental hydraulics, and in the
management of water and the water
environment
 Formed 1947
 Privatised 1982
 Limited by guarantee
 Non profit distributing
 Independent
 Over 280 staff
 £25m turnover

3. © HR Wallingford 2014
Flood forecasting typically focuses on
hazards e.g. river flows, water levels
Flood risk management considers wider
system performance e.g. defence failures;
floodplain extents, depths & velocities;
consequences; etc.
Opportunity for richer ‘live’ information:
 What type of action can I take to mend a
weak spot?
 Where should I enforce my flood defence
system?
 Which areas should I evacuate first?
 Which least-cost areas could be actively
inundated to save other areas?
October 2014
Why do we need something new?
Delft-FEWS User Days Page 3

4. © HR Wallingford 2014
Develop an operational flood-risk-
forecasting toolkit
Toolkit of models in Delft-FEWS shell:
 hydrology
 river system (1D)
 dynamic breach growth
 rapid flood spreading (2D)
 impact assessment (risk to life, critical
infrastructure, economic consequence)
Move to:
 risk-based approach
 probabilistic e.g. rainfall ensembles,
defence performance
October 2014
Collaboration Aims
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5. © HR Wallingford 2014
Application of toolkit
Not one size fits all
Select important processes (and
hence capability) for your
catchment
 fluvial vs coastal
 urban vs rural
 flood risk infrastructure e.g. storage,
defences, pumps, barriers, etc.
Flexibility to use hierarchy of data
and models - simple assumptions,
generic datasets, detailed
modelling
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6. © HR Wallingford 2014
Risk model framework
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7. © HR Wallingford 2014
Risk model framework
October 2014
Hydrological models e.g.
WFLOW: A distributed hydrological modelling platform which includes
derivations of SBM, HBV96, gr4h/d, a dynamic wave model, an associated flood
mapping model
HR Wallingford gridded model - computationally efficient, semi-distributed
hydrological model providing spatially coherent estimates of river flow and
groundwater level. (Counsell, 2014)
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Risk model framework
October 2014
River models - MASCARET
Open Source 1D open-channel hydraulic software
Originally developed by EDF, now managed by a consortia
(Goutal and Maurel 2002; Goutal et al, 2012)
Delft-FEWS User Days Page 8

9. © HR Wallingford 2014
Risk model framework
October 2014 Delft-FEWS User Days Page 9
Reliability models/data e.g.
Library of fragility curves for all asset types (> 60)
Tools such as:
 RELIABLE (Kortenhaus et al, 2008; FLOODsite),
 Hydra-Ring (Deltares)
Section 16
0.0
0.2
0.4
0.6
0.8
1.0
0.0 2.0 4.0 6.0 8.0 10.0
Water level (m OD)
Probabilityoffailure
Total
Uplifting
Piping
Sliding
Overturning
Reinforcement failure
Shear failure
Piping toe
Crest level
Indication extreme
w ater level
Reliability analysis
Numerical
Integration
Structure-specific
Fault tree
Limit state equation
Failure mode 1
Limit state equation
Failure mode 2
Limit state equation
Failure mode 3
Limit state equation
Failure mode ..n
Structure-specific
parameters, probability
distribution functions and
ranges
Structure-specific
fragility curve

10. © HR Wallingford 2014
Risk model framework
October 2014
Breach model - AREBA
Rapid breach growth - predicts flood hydrograph and
breach widths and depths for surface, headcut and
piping failures (Van Damme et al, 2012)
Delft-FEWS User Days Page 10

11. © HR Wallingford 2014
Risk model framework
October 2014
Inundation model - RFSM-EDA
Rapid Flood Spreading Model Explicit Diffusion wave
with Acceleration terms
Impact zones with volume-level and level-width curve
Minimal loss of accuracy in topography description
Developed by HR Wallingford (Jamieson et al, 2012)
Delft-FEWS User Days Page 11

12. © HR Wallingford 2014
Risk model framework
October 2014 Delft-FEWS User Days Page 12

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Risk model framework
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Risk model framework
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Risk model framework
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Risk model framework
October 2014
Impact models - economic assessment
Depth-damage curves for residential and commercial
property, agriculture, key infrastructure e.g. FIAT
(Deltares), Impact Calculator (HR Wallingford)
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
0 250 500 750 1000 1250 1500
DepthMetres
Damage £/m2
Depth Damage Curve
High
Suscept ibility
Band
Low
Suscept ibility
Band
Indica tive
Suscept ibility
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17. © HR Wallingford 2014
Risk model framework
October 2014
Impact models - risk to life
Agent-based modelling of the dynamic interaction of
the flood wave from a breach or dam break with
people, vehicles and property
A
B
Starting location
of person
Direction
of movement
of flood
wave
C
Target safe haven
N
Person
Safe haven
Road network
Escape route (on foot)
Escape route (in vehicle)
Floodwater
A
B
Starting location
of person
Direction
of movement
of flood
wave
C
Target safe haven
N
Person
Safe haven
Road network
Escape route (on foot)
Escape route (in vehicle)
Floodwater
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Example outputs - flood likelihood
(ensemble 1, DRAFT)
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Example outputs - flood damage (€, $)
DRAFT
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Example outputs - defence risk (€, $)
DRAFT
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Example outputs - Life safety
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Scoping Study
Develop FEWS model adaptors
 Stage 1 - develop initial adaptors and
simple model linking (proof of concept)
 Stage 2 - extend capability to capture
dynamic interactions (model coupling)
 Stage 3 - incorporate more sophisticated
risk capability
Pilot system
 Trial methods at two locations in close
liaison with end users
October 2014
Project Steps
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Questions - nature of information
What information would help your decision making?
 flood lead times, safest/quickest evacuation routes, knowing areas that can be
inundated to save other areas,
 weak defences, defences at risk of breach, defences at risk of overtopping
 probable flood extents, depths, velocities
 risk to people (injuries, fatalities)
 risk to critical infrastructure (power stations, transport, hospitals, etc.)
 economic risk, environmental risk
Would you use probabilistic information?
Would you use uncertainty information?
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Questions - nature of system
How would you want the system to operate?
 e.g. in FEWS, stand-alone, ability to plug in wider models, web-link
What are the system requirements?
 e.g. computational speed, robustness, data storage and management
How would you like the outputs to be communicated?
 e.g. target audience, online, mobile phones
What functionality would help to make it even more useful to you?
 e.g. mapping, visualisation, animations, inter-activeness re effectiveness of
measures
October 2014 Delft-FEWS User Days Page 24

25. Howbery Park, Wallingford, Oxfordshire OX10 8BA, United Kingdom
www.hrwallingford.com
October 2014