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A3) Dike reliability analysis

Start: 09/2017 (Part-time)
End: 09/2021
Status: Active

Contact details

Wim Kanning

Delft University of Technology

Expected outcome

Better models to assess the strength and performance of dikes using data from past events and experiments for optimising the design of flood defences.

Top and bottom-left: Floodwall failure on 17th Street Canal from Hurricane Katrina in New Orleans (source: Reslo et al. 2009 and IPET, 2005). Bottom-right: Rebuild New Orleans floodwall in 2013 (Photo by Bianca Hardeman).

Motivation and practical challenge

Seeing the aftermath of the New Orleans flood in 2005 motivated me to work on dike reliability modelling (bottom-right photo in 2013). The flood consequences were grave and very impressive (top and bottom-left photo in 2005). Also, for dike reliability modelling here in the Netherlands and abroad, that event made me realize firsthand the difficulties in predicting dike failures and the need to reduce uncertainties.

On the one hand, it showed me failure mechanisms that are rarely observed outside books and laboratories. On the other hand, it showed that modelling these failures involves much more than applying well-known failure models. Very uncertain soil conditions determine the strength of the levee. For example, very small weak zones in the soil proved critical for slope stability. Hence, modellers and designers of dikes should better account for the uncertain factors influencing the dike strength as much as possible.

Research challenge

To improve the modelling of failure mechanisms, I explore together with MSc and Ph.D’s from AllRisk and SAFElevee, how uncertainties in levee performance can be accounted for and best mitigated?

Components include data from top: the levee failure in Breitenhagen, Germany (source: SAFElevee and Gruber 2013); middle: the Flood Proof Holland backward erosion piping experiment (source: Pol 2018), and bottom: reconstructions around Kinderdjik in South Holland (source: SAFELevee). The piping and reinforcement schemes were adapted from van Beek (2015).

Innovative components

Our research helps in better understanding failure modes for optimising the design of flood defences to better comply with the new flood protection standard. Some of the unique topics that I’m working on as a daily supervisor of the following Ph.D. researchers are (see related projects):

  • The temporal development of failure mechanisms. Together with Joost Pol, we look at the progression rate of piping using full scale and small scale experiments. This temporal development shows how long piping needs to occur to result in flooding along the coast and on riverine areas.
  • Method to derive the most likely causes of failure of past breach events. Together with Job Kool, we improve the modelling of failure mechanisms via the structured deduction of failure scenarios from before and after data. We tested this approach to find the most likely cause of the failure of the Breitenhagen levee failure in Germany. The method is generically applicable to other locations.
  • Optimisation of dike reinforcements. With Wouter Jan Klerk, we look at various measures to, for example, reduce uncertainties on the soil parameters and implementing reinforcement techniques.

 

Relevant for whom and where?

Other researchers interested in the probabilistic analysis and failure mechanisms modelling. Organisations planning the reinforcement of dikes and authorities setting the design requirements.


The research include key locations in the Netherlands and abroad to use data from past events and experiments in the optimisation of flood defences.

Progress and practical application

For a detailed description of each finding, please click on the related outputs below. The analysis of the 2013 failure on the Breitenhagen levee in Germany shows that the slope instability most likely occurred as the result of an old breach. This old breach probably eroded the soil in front of the reconstructed dike, creating a direct connection between river and aquifer, thereby increasing pore water pressures.

By including temporal progression rates in the failure probability assessment due to piping, the improvements on the dike safety are small for riverine cases, which have long lasting flood levels. However, the improvements are much larger for the coastal cases, which have short lasting flood levels resulting in insufficient time for piping to fully develop. In the riverine cases, there is still a considerable delay in the expected time of piping of several days, which is beneficial for emergency response. Instead, for coastal cases, piping is less likely to occur with low duration floods.

Finally, our application example for five dike sections along the river Lek in The Netherlands shows that additional monitoring information is only valuable if the expected reinforcement decision is likely to be different.

Status for day-to-day practice

Dike strength modelling should be more focused on the what is in the subsoil and how this affects dike performance.

Next steps

Data from old failures will help our assessments of piping mechanisms (with Job Krool) and its progression rate (with Joost Pol), combined with more research into dike inspections (with Wouter Jan Klerk).

Last modified: 29/10/2020

Contributing researchers

Wim Kanning

Delft University of Technology

Supervisory team

prof.dr.ir. Matthijs Kok

Delft University of Technology

Contributing partners

Project outputs

Bayesian inference of piping model uncertainties based on field observations

Method to estimate model uncertainty based on failure and survival piping observations.

11/12/2019 by Wim Kanning et al.

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Bevat: Conference proceedings

Reliability-based partial factors for flood defences

Calibration procedure of the safety factors to ensure consistency between probabilistic and semi-probabilistic assessments at a cross-section and system level.

20/07/2019 by Wim Kanning et al.

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Bevat: Publication upon journal access

A Bayesian hindcasting method of levee failures: The Breitenhagen case

Hindcasting of prior and posterior probabilities of failure using limited observations and photos of the geometry of the slope, with the goal of finding the most likely cause of failure.

03/09/2020 by Wim Kanning et al.

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Bevat: Publication open access journal

Forensic analysis of levee failures: The Breitenhagen case

Generic steps to derive most likely failure scenarios from data prior, during and after a levee breach in Germany in 2013.

25/11/2019 by Wim Kanning et al.

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Bevat: Publication open access journal

Also applicable to this project

Temporal development of backward erosion piping

27/04/2021 by Joost Pol et al.

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Contains: Conference proceedings Publication upon journal access Report

Time-dependent reliability in flood protection decision making in the Netherlands

Exploration of the failure probability definition and the influence of including temporal correlation on failure probability estimates.

17/06/2018 by Wouter Jan Klerk et al.

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Contains: Conference proceedings

Influence of monitoring on investment planning of flood defence systems

Exploring the value of monitoring for the reinforcement of a dike segment.

11/12/2019 by Wouter Jan Klerk et al.

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Contains: Conference proceedings

Blogs

Bringing All-risk to practice: Martin’s recommendations

08/10/2020 by Wim Kanning

This blog is based on an informal interview between Martin Schepers (manager flood safety projects) and Wim Kanning (All-Risk researcher) on the development of...

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