Comparison of specific sediment transport rates obtained from empirical formulae and dam breaching experiments

Sediment transport rate determination plays an essential role in mathematical models of embankment dam breaching. The sediment transport formulae commonly used today were mostly determined under considerably different conditions than those existing during the breaching of embankment dams, i.e. in connection with relatively mild longitudinal slopes. However, due to the scarceness of sediment transport relations for sediment transport rates on steep slopes, these traditional formulae are frequently used in dam breach modelling. This paper contains a description of a physical model of a 0.86 m high sandy dike constructed and breached at an outdoor laboratory operated by the Faculty of Civil Engineering, Brno University of Technology, Czech Republic. The dike shape and material were the same for all experiments. The used material was homogeneous non-cohesive medium-uniform sand. The results of the experimental breaching of the sandy dike were discussed and compared with sediment transport rates obtained from various empirical formulae. The comparison shows differences between experimental and calculated sediment transport rates which in all analysed cases indicate overestimation of the breaching rate calculated by empirical formulae.