How does a levee work and why do levees fail during floods?

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1. 1

   On the vulnerability of river levees induced by seepage

   Journal of Flood Risk Management (Michelazzo et al.)Published Jul 21, 2016Checked Oct 18, 2026

   “Seepage through earthen levees is a mechanism often observed during floods and can lead to levee failure if combined with internal erosion. This notwithstanding, hazard maps for levee failure are often elaborated solely considering the mechanism of overtopping. In this work, the assessment of levee vulnerability relative to seepage is investigated by considering the characteristic time scales of the phenomena and the main factors upon which they depend. In particular, the persistence of hydrological load is compared with the critical time of seepage associated to the emergence of the phreatic line along the landside of levees. The results can easily be applied to long river reaches, elaborating of through seepage‐hazard maps and locating the levees that are more vulnerable to seepage failure.”

2. 2

   Effect of Seepage on Sand Levee Failure Due to Lateral Overtopping

   Water (Kang et al.)Published Dec 16, 2024Checked Oct 18, 2026

   “In this study, we conducted lateral overtopping failure experiments under seepage conditions that closely resembled those in experiments conducted in previous studies. Seepage was monitored using water pressure sensors and a distributed optical fiber cable that provided continuous heat for temperature monitoring in the levee. Τhe analysis of levee failure due to lateral overtopping, in the presence of seepage, was conducted using image analysis with digitization techniques and machine learning-based color segmentation techniques on the protected lowland side of the levee, targeting the same area. The results revealed that levee failure occurred more than twice as fast in experiments where seepage conditions were considered compared to the experiments where they were not. Thus, levees weakened by seepage are more vulnerable to overtopping and breaching. Consequently, employing a comprehensive approach that integrates various monitoring and analysis methods for assessing levee stability is preferable to relying on a single method alone.”

3. 3

   Generation and Simple Sensitivity Analysis of Fragility Surfaces Generated for Two Failure Mechanisms in River Levees for Flood Risk Analysis Using Monte Carlo Simulations

   World Environmental and Water Resources Congress (EWRI) (Lozano‐Valcarcel & Neira)Published May 18, 2017Checked Oct 18, 2026

   “Levee failure mechanisms have been studied and mathematically described by several authors. However, as some variables may follow stochastically distributed values, the statistical analysis may prove to be difficult and resource consuming. In this paper, Monte Carlo simulations were used to generate fragility curves for two failure mechanisms (overtopping and piping) which represent the behavior of a given levee when facing certain hydrological conditions. This surfaces might be used afterwards in a more complete flood risk analysis. Furthermore, a simple sensitivity analysis was carried out to determine the impact that some geometric variables had on the failure probability surfaces. The results of this analysis suggest that the levee’s failure probability due to overtopping is more sensitive to the levee’s taluses than to the levee’s crest height and width, while the failure probability due to piping is more dependent on the sand layer’s thickness than on the seepage length.”

4. 4

   Levee Fragility Behavior under Projected Future Flooding in a Warming Climate

   Journal of Geotechnical and Geoenvironmental Engineering (Vahedifard et al.)Published Sep 30, 2020Checked Oct 18, 2026

   “The historical and future flood levels were then applied in a set of transient coupled finite-element seepage and limit equilibrium slope stability analyses to simulate the levee subjected to extreme streamflow. Variability in hydraulic and mechanical properties of soils was addressed using a Monte Carlo sampling method to evaluate and compare the probability of failure of the levee under different historical and future climate scenarios. Three individual modes (underseepage, uplift, and slope stability) along with lower and upper bounds for the combined mode of failure were examined. The results showed that incorporating future floods into levee failure analysis led to considerable reductions in the mean factor of safety and increases in the levee’s probability of failure, suggesting that risk assessment based on historical records can significantly underestimate the levee’s failure probability in a warming climate. Despite inherent uncertainties in future projections and substantial variability across climate models, evaluating infrastructure against projected extremes offers insights into their likely performance for the future.”

5. 5

   Simulation of overtopping and seepage induced dike failure using two-point MPM

   SOILS AND FOUNDATIONS (Liang et al.)Published Aug 1, 2020Checked Oct 18, 2026

   “Fluvial dikes are important engineering works for protecting river valleys from flooding, so the stability of them is of great importance. In this paper, we apply a two-point two-phase formulation of the Material Point Method (MPM) to investigate the dike stability problem under the action of overtopping flows. Such a method has been incorporated in the Anura3D software (www.anura3d.com). In the model, the behaviours of soil and water are analysed in a single framework, so the interactions between the two phases are fully dynamic. The computational results agree well with the laboratory experiments. Parametric studies have been carried out to examine the effectiveness of various dike stability measures. The two-point MPM shows encouraging capabilities for studying a broad range of phenomena involving strong soil/water interactions.”

6. 6

   Numerical Modeling of Levee Failure Mechanisms by Integrating Seepage and Stability Processes

   GeoHazards (Ali et al.)Published Aug 8, 2025Checked Oct 18, 2026

   “The model employs van Genuchten-based soil water retention properties and experimentally derived hydraulic conductivities, with results validated against five experimental cases with varying hydraulic conductivity contrasts between the levee body and foundation soils. The simulations reproduced seepage front evolution and slope deformation patterns with good agreement with experimental observations. In cases with high permeability contrasts, the model captured foundation-dominant seepage behavior, while moderate- and low-contrast scenarios showed close alignment with observed phreatic line development. Slight deviations were noted in failure timing, but the framework demonstrated potential for reproducing seepage-induced instability in levees. The findings contribute to understanding how the internal soil composition governs levee performance under flooding and provide a basis for developing seepage countermeasures and early warning tools. This approach offers practical value for risk-informed levee design and flood management.”