Controlled scour process due to debris accumulation at bridge piers

Scour process at bridge piers is a very important topic for hydraulic engineers. In particular, it has to be deeply analyzed in order to avoid piers collapse. In the last decades, the scour process has been investigated by several researches. Mostly, studies focused on the prediction of the maximum scour depth and the evolution of the scour hole morphology. Furthermore, the scour process evolution received a particular attention as the comprehension of the physics of the phenomenon during the time is of fundamental importance to develop strategies oriented to control the scour geometry. Nevertheless, the analysis of the scour process cannot be limited to a configuration in which only an isolated bridge pier is present. Logs and wood transported by the flow can create obstacles in correspondence with the piers contributing to deeply modify the scour dynamic and resulting in an increase of the maximum scour depth. This paper aims to synthetize the dynamic of the scour process in the presence of a bridge pier and debris accumulation highlighting the similitudes and differences in terms of both equilibrium scour morphologies and scour process evolution for different configurations and hydraulic conditions.