International practice for the design of levees

1. International practice for the design of
levees
Dr Philip Smith
15th May 2014

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Background
 Imperial College, London
- BSc - Civil Engineering
- MSc - Soil Mechanics and Foundation Engineering
- PhD - Behaviour of Embankments on Soft Clays
 Most of career spent working on geotechnics at water’s edge
 Member ISSMGE TC 201: Dikes, Levees and Reclamations
 Co-author DEFRA FD2411: Performance of Flood
Embankments: A good practice review, 2007
 International Levee Handbook Chapter Lead - Chapter 9:
Design, 2013

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Levees
It’s just a lump of soil; how hard can it be?

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How hard can it be?

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How hard can it be?
Erosion
protection?
Transitions
& detailing?

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How can something so simple go so wrong?
 Complex composite structures, built from a mixture of natural
and manmade materials, often on poor (floodplain) ground.
 Subject to deterioration over time (settlement, desiccation,
animal burrowing, uncontrolled vegetation, erosion).
 Historically, often not designed or built to established
standards (particularly rural levees); lack of historical records.
 Will stand for decades without experiencing design flood and
so get forgotten; maintenance put off until next year…….
 Levees get taken for granted; the physical barrier they create
can give a false sense of security.
 Only as strong as the weakest link!

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Levees – A clear and present danger?

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The International Levee Handbook
In 2008, organisations from France,
Germany, NL, the UK, Ireland and
the USA agreed to share the effort of
producing good practice guidance for
levees.
Initiative was spawned by the severe
problems experienced in New
Orleans during Hurricane Katrina and
by the growing awareness of the
general lack of guidance for the
design and operation of levees.
Work on the International Levee Handbook (the ILH) began in 2009.
The ILH was published in 2013

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International collaboration for the ILH
Major contributors

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ASCE key findings after Katrina
Transition failure:
The system did not
function as a system.
Low cost structures:
Poor levee performance
correlated with the use of
poor quality materials.
Cost-cutting solutions:
Levees built with erodible materials
were vulnerable to overtopping.

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ASCE key findings after Katrina (2)
Inadequate design:
Some “I” Wall failures occurred
when water level was below
design levels as a result of
(unconsidered) wall deflections.
(strain incompatibility).
Lack of resilience:
Numerous “I” walls failed due
to overtopping and erosion.

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History repeating itself?
Many of the New Orleans failure mechanisms had been
experienced before.
Cooling & Marsland, (1954) identified many of the same
mechanisms after the North Sea Floods of 1953.
Ironically, Cooling & Marsland complimented USACE for its good
work on the flood defences of the Mississippi Delta but this good
practice had become forgotten over time.
Extreme flood events occur rarely but flood defences must
perform well when these events do eventually hit.
If there is one lesson we should learn from the past, it’s that
we are not good at learning lessons from the past!

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Extreme Events
Overtopping of levee beneath Paris Road Bridge, New Orleans

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14
On a nicer day!

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International Levee Handbook - Objectives
The three main objectives of the International Levee Handbook
were:
 To provide a comprehensive and definitive guide to good
practice;
 To be a non-prescriptive reference intended to be used in
conjunction with national codes and standards; and
 To provide decision support and guidance in the application of
national codes and standards.
The ILH was targeted at two levels of understanding, technically
competent practitioners and technically aware clients.

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International Levee Handbook - Limitations
 The International Levee Handbook (ILH) is focused on levee
operation, assessment, design and construction.
 The ILH is not intended to be a complete guide to flood risk
management.
 The opening chapters remind readers that levees are just one
of the tools available for flood risk management.
 Levees are not always the right solution and in some cases
they may be the wrong solution.

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International Levee Handbook - Limitations

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ILH Structure
In early stages of ILH
development, there was much
debate about the starting point.
In the end, it was recognised that
many levees had already been
constructed.
Therefore, early chapters focus on
operations and maintenance, the
middle chapters provide toolboxes
for site assessment and calculation
methodologies. The final chapters
cover design and construction.

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ILH Organisation of Chapters

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ILH Organisation of Chapters
Chapter Title Lead No. Pages
Ch. 1 – Introduction Technical Editing Team 8
Ch. 2 – Understanding Levees; Basic Concepts UK / Ireland 40
Ch. 3 – Form, Function & Failure Modes of Levees France 130
Ch. 4 – Operation and Maintenance US 106
Ch. 5 – Inspection, assessment & risk attribution France 96
Ch. 6 – Emergency Preparedness US 66
Ch. 7 – Site Characterisation and Data Management UK / Ireland 298
Ch. 8 – Physical Processes and Tools France 230
Ch. 9 – Design UK / Ireland 218
Ch. 10 – Construction US / Netherlands 100
Glossary / Abbreviations Technical Editing Team 57
Total 1349

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Summary
• The International Levee Handbook (the ILH) is a compendium
of good practice which offers comprehensive guidance on the
design, construction, maintenance and improvement of levees.
• Compiled by an international team from France, USA and
UK/Ireland supported by Netherlands and Germany.
• Written by levee practitioners and experts from contributing
nations.
• Written for levee owner/operators as well as designers.
• Decision support framework rather than being a prescriptive
code of practice.

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Summary
• Much of relevance in the ILH to the topic of levee maintenance,
assessment, investigation, design and construction in Australia
(see FMA paper).
• By bringing together practitioners and those responsible for
operating and managing levees, the ILH has effectively created
an international community of practice for levees.
• The ILH contributors are now working to form an international
community of practice for levees. This will be open to
incorporate individuals from other nations not directly involved
with the original project so that knowledge and good practice
can continue to be shared on an international basis.

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Thank you
To download the International Levee Handbook
go to: www.ciria.org/ILH
Philip Smith
Royal HaskoningDHV
E: philip.smith@rhdhv.com