Abstract: Embankments play a vital role in flood control engineering systems, and any breach in these embankments can result in severe disaster losses. Therefore, it is crucial to understand the relationship between the development rate of embankment breaches and hydraulic factors to accurately predict breach processes and flood evolution. By analyzing experimental data from series breach tests of non-cohesive sandy embankments, we obtained the relationship between hydraulic factors (discharge and unit-width discharge) and breach development rates (transverse widening rate and vertical down-cutting rate). Findings reveal two major developments of breach, namely, transverse widening and vertical down-cutting. Breach discharge rate is positively correlated with breach development rate, although the specific relationship depends on inflow conditions, making it difficult to express uniformly for all experimental scenarios. Nonetheless, an exponential relationship exists between unit-width discharge and breach development rate. Based on this relationship, a calculation model is established with unit-width discharge as a parameter to simulate and analyze the development process of breaches, including transverse widening and vertical down-cutting. The results demonstrate a strong agreement between the simulated situation and the actual breach development process, thus confirming the accuracy, scientific validity, and simplicity of the calculation model.

Key words: non-cohesive embankment, breach discharge, unit-width discharge at breach, down-cutting rate, transverse widening rate, computational model of breach development process