Experimental Study of Instantaneous Dike-Break Induced Flow Based on Simultaneous Measurement of Surface Morphology and Velocity Field

Abstract Dike failure is a disaster that brings extensive damage. Studying the characteristics of breach flow is of great practical significance for breach closure and reducing flood damage. However, experimental research on the surface morphology and velocity field of breach flow during the process of dike-break remains relatively limited. In this study, a large-scale experimental model of instantaneous dike-break induced flow under various flow conditions was conducted. The simultaneous measurement of water surface morphology and surface velocity fields near the breach was achieved using three-dimensional surface particle tracking velocimetry measurement technology. Based on the morphological evolution of the breach water surface, the dike-break process was divided into three stages: initial stable water tongue formation, gradual submergence, and eventual disappearance. The dimensionless water surface profile elevation along the breach centerline during the first stage exhibited similar characteristics under varying experimental conditions. The surface velocity also exhibited relatively stable distribution patterns along the breach centerline during this stage. The dimensionless water-level difference between the main channel side and floodplain side decreased with increasing initial water depth. However, the water-level difference between the downstream and upstream sides within the main channel increased with higher initial river velocities. The surface velocity of breach flow exhibited an initial increase to a peak followed by a decline, with the peak value showing a positive correlation with the initial channel depth. These findings revealed the evolution of breach flow surface morphology and velocity field, enhancing understanding of hydrodynamic processes of dike failure.