Environmental fluid mechanics of minimum energy loss weirs: hydrodynamics and self-aeration at Chinchilla MEL weir during the November–December 2021 flood event

Abstract During the recent decades, a number of overflow embankment protection systems were implemented. One design is Minimum Energy Loss (MEL) weir, developed to pass large flood events with minimum energy loss and low erosion. Several MEL weirs have successfully operated for decades in Australian catchments affected by heavy tropical sub-tropical rainfalls very flat gradients. Their historical performances are discussed confirmed capability floods small afflux little environmental impact including no significant erosion at abutments. major flood, visual quantitative observations undertaken Chinchilla weir. On smooth converging chute, showed that inception self‐aeration was three‐dimensional process gradual change free‐surface roughness, from glassy free-surface very-rough choppy surface. An optical technique (OF) implemented derive contour maps surface velocities based upon video movies taken sturdy tripod. The self-aerated flow velocity data close backwater equation self‐aerated region, while highlighting regions high- low-velocities across chute. OF streamwise fluctuations aerated consistent broad literature on measurements. ratio transverse turbulence intensity indicated strong anisotropy turbulence.