Experimental and analytical prediction of local scour at hydraulic structures

An experimental investigation was carried out to examine local scour downstream of grade-control structures (GCSs) under the influence of a two-dimensional jet flow. The impinging jet downstream of a GCS generates substantial erosive forces, leading to pronounced local scour that can compromise the structural stability and safety of the system. Therefore, a key aspect of GCS design is developing a comprehensive understanding of the scouring process and enhancing the ability to predict the temporal and spatial evolution of the scour hole. This study focuses on the development of a scour hole downstream of a sloped grade-control structure (GCS) in alluvial channels with a noncohesive sediment bed. Based on a series of laboratory experiments and data collected from previous studies, the effect of the downstream face slope of a GCS on scour morphology was analyzed. The results led to the proposal of a new scaling approach, yielding general equations for predicting equilibrium scour profiles at a wide range of hydraulic structures and flow conditions in fluvial and coastal areas. A set of predictors for the scour characteristic parameters under equilibrium conditions is also proposed. To facilitate practical application, these equations were expressed as functions of variables that practitioners can easily define.