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June 2018
International best practice in levee system flood risk analysis
Ben Gouldby ASFPM Phoenix 2018
© HR Wallingford 2018
Overview
Introduction to the levee partnership
St Louis pilot site analysis
UK Approach
Overview of approaches: comparisons
June 2018 Page 2
© HR Wallingford 2018June 2018 Page 3
© HR Wallingford 2018
St Louis:Upper Wood River Levee System
June 2018 Page 4
© HR Wallingford 2018
St Louis : method comparison
5June 2018
© HR Wallingford 2018
Range of structure types
June 2018 Page 6
© HR Wallingford 2018
All methods – risk based
June 2018 Page 7
Risk = f( Probability and consequence)
© HR Wallingford 2018
Load
Probability
SourceProbability
of failure
Load
Pathway
Pathway
DamageReceptor
Depth16th March 2018
© HR Wallingford 2018
A structured approach to the analysis of
the flood risk system
16th March 2018
© HR Wallingford 2018
Levee segmentation
June 2018 Page 10
© HR Wallingford 2018
Levee segmentation
June 2018 Page 11
© HR Wallingford 2018
All methods – integrated simulation
June 2018 Page 12
© HR Wallingford 2018
Environment Agency Consequences: Economic
June 2018 Page 13
© HR Wallingford 2018
14
Environment Agency ResultsAsset contribution to risk
Reported for
Residential and non-residential buildings,
And structural failure (breach) and non-failure (overflow / overtop /
seepage)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
25242322212019181716151413121110987654321
EAD
($)
Asset ID
Seepage Breached
© HR Wallingford 2018
Rijkswaterstaat reliability analysis
15June 2018
© HR Wallingford 2018
USACE reliability
16June 2018
© HR Wallingford 2018
Environment Agency: formal reliability analysis
June 2018 Page 17
© HR Wallingford 2018
Summary of reliability analysis:Fragility
18
Formal reliability analysis
Expert Judgment
June 2018
Model parameters
June 2018
Formal expert elicitation
Model/data parameters
© HR Wallingford 2018
Summary of reliability analysis
19
Probability of failure
within the levee system
June 2018
June 2018
Probability of failure of
each segment
© HR Wallingford 2018
Rijkswaterstaat and USACE Consequences:Life-loss
20June 2018
© HR Wallingford 2018
Summary of consequences
21
Life-loss
June 2018
June 2018
Economics
© HR Wallingford 2018
Conclusions
• Fundamental concepts and principals consistent
• Differences in relation to treatment of consequences
• Differences in relation to the method flood levee
reliability analysis
• To a certain extent differences reflect the different
topographical feature of the countries
June 2018 Page 22
© HR Wallingford 2018
Questions?23
Rijkswaterstaat:
Deon Slagter, Cees Henk Oostinga + many others
USACE:
Eric Halpin, Tammy Conforti, Nate Snorteland, Jason Needham +
many others
Environment Agency:
Claire Hollingsworth, Adrian Rushworth, Dave Hornby, Owen Tarrant
HR Wallingford:
Jonathan Simm, Mike Panzeri, Gordon Glasgow
June 2018
Acknowledgements
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