Investigation into lateral widening process of farm dike breach using a sketched physical model

In order to investigate the lateral widening process of farm dike breach, a generalized physical model was constructed. Farm dikes with different soil properties in experiments were built using the soil excavated from a prototype farm dike located in the Lower Yellow River. The variation processes of hydraulic characteristics and breach widths were measured and analyzed. Experimental results show that the lateral widening mechanism during the process of dike breach was clarified by two aspects, including the lateral erosion of the dike soil below the water level, and the collapse of the dike soil above the water level. The flow velocity at breach site increased first and then decreased, with a peak value of 1.1 m/s. The water depth kept decreasing, but the decreasing rate gradually became smaller. Water depths, breach velocities and discharges, and lateral widening rates increased with an increase of inlet discharge. An empirical formula to calculate the lateral widening rate was proposed based on the analysis of factors influencing the farm dike breach, and the calculated widening process agreed well with the measured process. These results can provide experimental data not only for the research on the lateral widening process of farm dike breach, but also for the validation of numerical models.