Expected outcome
Better models to assess the strength and performance of levees using data from past events and experiments for optimizing the design of flood defenses.
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 levee reliability modeling (bottom-right photo in 2013). The flood consequences were grave and very impressive (top and bottom-left photo in 2005). Also, for levee reliability modeling here in The Netherlands and abroad, that event made me realize firsthand the difficulties in predicting levee failures and the need to reduce uncertainties.
On the one hand, it showed me failure modes that are rarely observed outside books and laboratories. On the other hand, it showed that modeling 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, modelers and designers of levees should better account for the uncertain factors influencing the levee 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?
Key goals: Fudamental understanding
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).
Innovative components
Our research helps in better understanding failure modes for optimizing the design of flood defenses to better comply with the new flood protection standard. Some of the unique aspects that we develop with the various Ph.D. researchers are:
- 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.
- Optimization of levee 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. Organizations planning the reinforcement of levees 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 optimization of flood defenses.
Progress and practical application
For a detailed description of each finding, please refer to the related outputs. 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 beneath the reconstructed levee, 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 levee safety are small for riverine cases but much larger for the coastal cases. 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
Levee strength modeling should be more focused on the what is in the subsoil and how this affects levee performance.
Next steps
Data from old failures will help our assessments of piping mechanisms and its progression rate, combined with more research into levee inspections.
Last modified: 26/04/2020
Explore the contact details to get to know more about the researchers, the supervisory team and the organizations that contribute to this project.
Contributing researchers
Wim Kanning
Delft University of Technology
Contributing partners
As soon as available, explore the storyline to get to know more about the main methods or prototype tools that were developed within this project.
Ecological benefits of a sheltered channel parallel to the main river
The longitudinal dams minimize the effects of commercial navigation to protect the habitat of fish and macroinvertebrates.
Beatriz Marin Diaz
NIOZ
Guido Remmerswaal
Delft University of Technology
Juliette Cortes Arevalo
Koen Berends
prof.dr.ir. Matthijs Kok
Delft University of Technology
Matthijs R.A. Gensen
University of Twente
Wim Kanning
Delft University of Technology
View storyline Explore the output details for available publications to get a glance of the innovative components and implications to practice as well as the links to supporting datasets.
Some recent research outputs include:
- Klerk W.J., Kanning W, Kok M (2018) Time-dependent reliability in flood protection decision making in the Netherlands. ESREL2018 conference.
- Kool, J., Kanning, W., Heyer, T., Jommi, C., Jonkman S.N. (2019). Forensic analysis of levee failures: the Breitenhagen case. Revision accepted to International Journal of Geoengineering Case Histories.
- Klerk, W.J., Kanning, W., van Veen, N., Kok, M. (2019) Influence of monitoring on investment planning of flood defence systems. Proceedings Conference ISGSR2019.
- Kanning,W and T. Schweckendiek (2019) Bayiesian nference of piping model uncertainties based on field observations. Proceedings Conference ISGSR2019.
- Pol, J.C., van Beek, V.M., Kanning, W., and Jonkman, S.N. Progression rate of backward erosion piping in laboratory experiments and reliability analysis. Proceedings Conference ISGSR2019.
- Jongejan, R.B., Diermanse, F., Kanning, W., Bottema, M. (2020). Reliability-based partial factors for flood defenses. Reliability Engineering & System Safety. Volume 193, January 2020.
Take a look to the dissemination efforts and application experiences which are available in the news items and blogs.
