Scour which occurs due to a constriction in the water channel openings

• A. Scour
• B. Scour, Local
• C. Scour, General
• D. Scour, Bridge

Answer: (C)

General scour describes erosion of the streambed that happens over a reach when the flow area is constricted, causing the water to speed up along the channel. The increased velocity raises bed shear stress across the entire downstream reach, so sediment is removed over a length of channel rather than at a single point. Local scour, in contrast, occurs specifically around objects like bridge piers or abutments where vortices create a localized hole. Bridge scour is a broad term that can include both local and general effects, but when the erosion is due to a constriction in the channel opening, the precise term is general scour.