Spur dikes are generally employed to mitigate riverbank erosion and channel instability. This study investigates the effect of downward seepage on the temporal migration of scour depth around spur dikes. A series of laboratory experiments using rectangular spur dikes was conducted under three conditions: no seepage, 5% seepage, and 10% seepage of the main flow. Bed elevation data were collected over time using an Ultrasonic Ranging System (URS), and flow velocities were measured with an Acoustic Doppler Velocimeter (ADV). The celerity of scour depth migration was analysed using wavelet transform-based cross-correlation to evaluate scale-dependent celerity. Results indicate that downward seepage increases streamwise velocity and enhances sediment mobility, leading to a deeper and faster developing scour hole. Time-scale celerity increases with seepage percentage and decreases with time as the scour approaches equilibrium. These findings provide insights into the interaction of hydraulic structures and subsurface flow, informing design practices for erosion control in alluvial channels.