Analysis of a fluvial groynes system on hydraulic scale model

The paper presents the results of an experimental investigation of fluvial groynes conducted on a mobile bed scale model. The model reproduces a reach of the River Po, Italy, in which a series of groynes have been designed to improve navigability during dry periods. The experiments were conducted using light plastic material. The density and the grain size of the material were calibrated according to the similarity of the mobility parameter. Focusing on the processes of sediment deposition and transport within the groynes field, the experimental analysis showed the formation of a bar between two consecutive groynes. The formation of the bar is likely to have been related to the suspended load whipped up by the longitudinal vortex responsible for the local scouring around the head of the groyne. This was one of the most important aspects of the investigation; in fact, the formation of a deposition bar starting downstream from each groyne significantly changed the hydrodynamic field between the groynes. The research also investigated localized scouring, the effects of a variety of groyne parameters, and two different foundation typologies, stiff and flexible, realized with rip-rap stones on filtering ballasted mats.