Experimental Study of Dike-Break Induced Flow Generated by Instantaneous Opening of the Side Gate

A large-scale experimental model of instantaneous dike-break induced flow was conducted in this work. Water level variations in the river channel and floodplain, breach discharge, and the surface velocity field at the breach were measured during dike failure. The results show that: (i) The water level in the river rapidly decreased to a minimum (15%–22% of the initial water depth), then began to gradually rise, and finally approached stable. The water level in the floodplain gradually increased and ultimately tended towards stability. (ii) The breach discharge initially increased to a peak, then gradually decreased with a decreasing rate. The peak discharge was not only related to the initial river water level before dike-break, but also to the river velocity. Under the same conditions, the higher the river water level or the higher the river velocity, the greater the flood peak at the breach. And (iii) During the process of dike-break, the surface velocity of the breach flow gradually decreased. Other things being equal, a higher river water depth or a higher river velocity led to a larger surface velocity of the breach flow. These findings help better understand the hydrodynamic process and provide data support for models.