Using PTV through an embankment breach channel

Abstract

Particle tracking velocimetry was used to determine for the first time the surface velocities upstream, downstream, and through experimental embankment dam breach channels at all stages of breach development. A series of experimental tests was performed, which used varying initial breach geometry. The measurements were made using Styrofoam surface tracking particles and three different video camera angles to obtain 3-dimensional velocity measurements, which were calculated using ArcGIS. Space-time contour maps of velocity were then interpolated for each of the breach scenarios. A maximum surface flow velocity of 2.1 m/s, corresponding to 21 m/s at prototype scale, was measured at the downstream end of the breach channel near the time to peak for the breach outflow. The surface velocities were also converted to average velocities and used in conjunction with breach flow measurements to determine the depth of flow through the breach channel and to make estimates of the sub-aqueous breach geometry. Estimates of flow depth through the breach were used to compare measured outflow results with those determined analytically using the broad-crested weir equation.