Roll waves in slow motion

Roll waves are some free-surface instability observed in shallow supercritical flows. Such flows can exhibit instabilities in the form of initially minor surface disturbances growing up with time, and becoming moving hydraulic jumps travelling at greater speed than the mean flow. This slow motion video illustrates three-dimensional multi-train roll waves down a steep concrete slope. Slow motion [120 fps] view of roll waves at Toonumbar Dam in February 2026. Copyrights Hubert Chanson 2026. References https://www.youtube.com/@Hubert_Chanson/search?query=roll%20waves DRESSLER, R.F. (1949). "Mathematical Solution of the Problem of Roll-Waves in Inclined Open Channels." Communications in Pure and Applied Physics, Vol. 2, No. 2-3, pp. 149-194. MONTES, J.S. (1998). "Hydraulics of Open Channel Flow." ASCE Press, New-York, USA, 697 pages