You can download Paul's presentation here.
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Precision flood models and spatial analysis of flood risk in Great Britain www.ambiental.co.uk
Transcript of You can download Paul's presentation here.
Precision flood models and spatial analysis of flood risk in Great Britain
www.ambiental.co.uk
Presentation Structure
1. Flooding in Great Britain: historic context
2. Introduction to flood hazard modelling
3. Flood risk at a property level
4. Analysing risk and presentation of results
5. Summary remarks and questions
Introduction
British company which grew out of Cambridge University
Commercialise flood risk science & flood model development
High Precision Flood risk Mapping & Modelling for insurers
Ambiental grew from cutting edge modelling
dreamt, designed and built at Cambridge University
1997: Founded as a
partnership of
researchers at
Cambridge University
2007: FlowRoute™
enables rapid pluvial
flood modelling
2010: Launch UK
FloodMap™ to
insurance – Fluvial,
Pluvial and Tidal
datasets
2005: Launched
Flowroute –
international flood
risk mapping
visualisation software
2009: FlowRoute™
to the cloud
2012: Launch Swiss,
Czech, Australian, Irish
and Latin American
Flood Maps
2014: Launch Asia-
Pacific, European
and American
Flood Maps,
UKFloodMap 4™,
Australia Cat Model
2015: Launched
FloodScore™ and
Australia
FloodCat™ in
ELEMENTS
1. Flooding in Great Britain
Historic evidence of flooding
A Recurring Phenomenon…
2007 2008 2009 2010 2012 2013/4
United Kingdom
55,000 homes flooded
13 fatalities
Estimated damage:£3 billion
Northumberland
1000 properties flooded
Estimated damage: £10
million
Cumbria
Worst floods in 55 years
4 fatalities
Estimated damage: £100
million
Cornwall
350 propertiesflooded
Estimated damage: £6
million
UK & Ireland
Wettest summer in 100 years
9 fatalities
Estimated damage: £1
billion
England
Wettest Dec/Jan since 1876
17 fatalities
Estimated damage: £1
billion
Sources of Flooding
• Fluvial (River Water)
• Tidal / Coastal (Sea Water)
• Pluvial (Surface Water)
Primary Sources
• Flood Defence Breach
• Dam Breach
• Sewer
• Groundwater
Secondary Sources
Likelihood of Flooding
Flood Risk Increasing in Great Britain
“One in six homes in England is at risk of flooding” (source: EA)
“500,000 homes at high risk” (source: Willis Research Network)
Other considerations:
• “Flood Rich” period?
• Climate change?
• Decreased public spending on flood defences
• Flood RE due to launch in summer 2015
2. Flooding hazard mapping
Comprehensive Mapping Backbone
The key spatial data inputs used to build a flood model:
Hydraulic Modelling
Modelling Approaches
Hydrodynamic 1D (e.g. Hec-Ras)
Hydrodynamic 2D - FlowRroute
Statistical / Basin Fill
FlowRoute™ used for solving simplified version of shallow-water equation.
2D Flood modelling differs from 1D in that it represents differing flow conditions across a floodplain.
A 2D Hydrodynamic Model divides the floodplain into a gridded domain –obstacles can be taken into account.
Water flow between grid cells dependant on roughness and water levels between iterative time steps.
National: UKFloodMap™
Quality Assurance Activity
Error types:
Examples:
A B C D E F
Flow Obstruction Domain Too Small Inflow Node Incorrect Not Steady-State Instability Do Not Use
Build up of water behind obvious channel blockage(note: 'Channel' blockage as opposed to 'Floodplain' blockage, which is ok).
Shear edge in the floodmap (either straightor curved) which looks completely unatural due to domain cutting off flow.
Gap in floodplain after merging of all layers dueto flood flow not yet reaching this part of the model.
Model simulation instability producing unnatural results. Note 'checker-board' effect.
Data Validation
Data Validation: Walton Bridge 2014
Walton Bridge
3. Flood risk at property level
How do we think of risk?
0.00
0.50
1.00
1 3 5 7 9 11 13 15
Me
an D
amag
eR
atio
Intensity
Vulnerability Curve
Establishing the Hazard Relationship
Establishing the Hazard Relationship
Establishing the Hazard Relationship
Extracting Hazard Data at the building level…
FloodScore™ Cloud Service
1
2
3
Instant access to professional flood risk information for any property within Great Britain.
Search for a property:
Select a property from the list:
View detailed flood data and summary of risk:
In partnership with:
4. Analysing flood risk
FloodScore Analysis
FloodScoreRisk of moderate
depth flooding
Properties at risk
in Great Britain
0 % Low 80.4%
1 – 20 % Low 6.4%
21 – 40% Moderate 2.6%
41 – 60 % Moderate 2.1%
61 – 80 % High 4.1%
81 – 100 % High 4.3%
• 6 million (20%) properties have a risk of flooding
• 2.6 million (8%) properties have high risk of flooding
FloodScore Analysis:
By Region
• Combined flood risk varies across Great Britain when regionally aggregated.
• The North East has the lowest flood risk overall.
• When flood defences are operational the East Midlands has the highest flood risk.
With
flood
defences
FloodScore Analysis:
By Region
Without
flood
defences
• Combined flood risk varies across Great Britain when regionally aggregated.
• The North East has the lowest flood risk overall.
• When flood defences are operational the East Midlands has the highest flood risk.
• When flood defences are inoperable London is shown to be at greatest risk.
FloodScore Analysis: By Town
The mean combined FloodScore for towns in Great Britain: 9%
The top ten towns with the highest and lowest flood risk:
Top tens based on all settlements over 10,000 properties unprotected by flood defences
Top ten towns with lowest flood risk
Mean FloodScore
1 Larkhall 0.9
2 Livingstone 0.9
3 Motherwell 0.9
4 Hamilton 1
5 Wishaw 1
6 Cumbernauld 1
7 Glenrothes 1.2
8 Bellshill 1.4
9 Morley 1.5
10 Felling 1.6
Top ten towns with highest flood risk
Mean FloodScore
1 Boston 95.6
2 Spalding 93.4
3 March 89
4 Skegness 87
5 Wisbech 74.2
6 Grimsby 49.7
7 Bridgewater 40.8
8 Cleethorpes 39.4
9 Edmonton 39
10 Chertsey 37
5. Summary and conclusion
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twitter.com/floodexpert
Thank you… any questions?
