Piers in the waterway affect the velocity distribution across the channel and may act as barriers to floating debris. In addition, they also affect channel geometry by causing general and local scour in the vicinity of the bridge. The level of hydraulic efficiency of an unobstructed channel may be reduced by several percent if piers are placed in the waterway. Pier design should consider the probability that the channel alignment and geometry will change with time.
Additional publication details
EFFECT ON BRIDGE PIERS ON STREAMFLOW AND CHANNEL GEOMETRY.