Scour in hydraulic engineering

As a result of damage and failures due to undermining of foundations and the blockage of water flow caused by sediment aggradation downstream of scour holes, scour in hydraulic engineering has become an important issue in recent decades. This paper presents recent research on: (a) plunge pool scour in which a variety of effects were investigated; (b) bridge piers for which spatial and temporal scour development was described using particle image velocimetry for a test case; (c) the failure of riprap-protected spur dykes in a straight river reach. In all three fields, the main features of scour are described based on similitude according to Froude—that is, using the densimetric Froude number of the approach flow as the dominant parameter. The large number of parameters involved were controlled with suitable experimental setups allowing for the determination of the governing effects of a scour problem. Results are presented that readily apply to river engineering problems.