ABSTRACT:

Overtopping-induced breaches in earthen dams pose a growing threat, increasingly exacerbated by extreme rainfall events. We present a probabilistic framework to quantify erosion risk by incorporating uncertainties in both hydrologic loading and dam material resistance. Fragility curves are developed to estimate surface erosion probabilities across a range of flood intensities. Coupled hydrologic and hydraulic analyses link rainfall dynamics to dam overflow behavior. Uncertainty in the interaction between applied and critical shear stresses is propagated using Monte Carlo simulations. Applied to three dams affected by the 2015 South Carolina floods, the framework captures distinct erosion responses driven by excess shear stress, with predicted probabilities aligning with observed outcomes. In contrast to deterministic methods that oversimplify hydraulic-material interactions, this probabilistic approach offers a more robust basis for dam safety assessment and flood mitigation planning.