The influence of deviating conditions on levee failure rates
J.J. Kool (TU Delft - Hydraulic Structures and Flood Risk)
Willem Kanning (TU Delft - Hydraulic Structures and Flood Risk)
Sebastiaan Nicolaas Jonkman (TU Delft - Hydraulic Structures and Flood Risk)
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Abstract
This study introduces a method for assessing the annual failure rate of levees based on information from historical floods, while also considering the return period of these past events. Also, an approach has been developed to quantify the influence of deviating conditions on failure rates. The presence of deviating conditions at failed and survived levee sections is analyzed based on satellite observations. Bayesian techniques and likelihood ratios are used to update the failure rate as a function of the presence of deviations. The river system of Sachsen-Anhalt, Germany, is used as a case study. It experienced severe floods with many levee failures in the years 2002 and 2013. It is found that the presence of geological deviations had a significant influence on the observed failure rate and that failure rate increases with the magnitude of the hydraulic loading. It is also discussed how the expected number of failures in a system during a flood event with a certain magnitude can be estimated. The results of this study can be used to further optimize soil investigations, calibrate the results of more advanced reliability analyses and complement risk assessments, particularly in data-poor environments.
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