Semi-parametric model of an overtopped dike breach

This paper uses a semi-parametric approach to model the breaching of overtopped dikes composed of non-cohesive material. The hydraulic discharge is computed on the basis of a broad-crested weir formula, while the erosion is modelled using the Smart sediment transport formula. Breach length is computed on the basis of sediment transport rate where the Exner equation is solved numerically. To simplify the model, two stages of the breach processes are assumed. In stage I the downstream dike crest does not reach the centre line of the original crest and both upstream and downstream edges of the crest move upstream. In stage II the downstream dike crest reaches the centre line of the original crest and it moves vertically downwards. The upstream movement of the dike toe stops, resulting in a decrease of the angle of the downstream face of the dike. A comparison of measured and computed values shows that the numerical computation gives good results in predicting reservoir water level and elevation of the mid-breach.