An analytical process-based approach to predicting breach width in levees constructed from dilatant soils

An accurate prediction of the breach widening rate after the onset of a levee failure is essential for flood risk assessments. Current state-of-the-art analytical breach growth relations are empirical in nature. The large variety in loading conditions, levee design, and levee construction material, combined with the limited amount of accurate measurements of breach growth, make the development of accurate empirical breach growth relations challenging. In this paper, a process-based breach widening relation is presented for levees constructed of dilatant soils. The process-based relation is derived from the weir flow equation and a process-based erosion equation. The breach widening relation can account for the effects of variations in soil parameters. For those cases for which soil parameters are unknown, a calibrated catch-all-coefficient is provided. The relation is benchmarked against the state-of-the-art empirical breach growth relation used in the Netherlands and validated against data on historical levee failures and experimental data.