Pier with no exposed footing

ys/y1=2.0*K1*K2*K3[(a/y1)0.65]*(Fr10.43)
Where:
ys = Local pier scour depth
y1= flow depth just upstream of the pier
K1= Correction for pier nose shape
K2= Correction for attack angle
K3= Correction for stream bed condition
a= pier width
V1= Flow velocity just upstream of pier
Fr1= Froude number = V1/(g*y1)0.5

Units to be consistent in ft & ft/sec or m & m/sec. Refer to HEC-18 for guidance in determining the factors in this equation.