ys = 0.32 b φ Fr10.2 (be / b)0.62 (y1 / b)0.46 (b / D50)0.08 + b
[ SI units (metric): ys, y1, and b in m;
v1 in m/s; D50 in mm ]
[ U.S. Customary units: ys, y1, and b in ft;
v1 in ft/s; D50 in mm ]
[ Fr = Froude number; g = gravitational acceleration ]
To determine the bridge scour depth ys,
the calculator requires the following information:
Flow depth directly upstream of the pier y1, in m (or ft).
Mean flow velocity directly upstream of the pier v1, in m/s (or fps).
Pier width in a horizontal direction normal to the flow b (Fig. 1), in m (or ft).
Fig. 1 Definition sketch for pier scour.
Pier length L (Fig. 1), in m (or ft).
Angle of attack θ of the flow, in degrees.
Pier nose shape (Fig. 2), to determine the shape co-efficient φ.
φ = 1.3 for square-nosed piers.
φ = 1.0 for round-nosed piers.
φ = 0.7 for sharp-nosed piers.
Fig. 2 Common pier shapes.