bridge scour and d50

[giulianb]

Dear HEC-USERS

I am performing a scour analysis at a single pier for a proposed bridge
but i have some problems with d50: the scour remains very high, more than 2 meters even if i set for d50 very high values - 100-200-1000 mm.
is there any range for this Variable?
Any comments on the method that I should use, would be appreciated
giuliano barbarito

[MattZ]

There are many factors involved in the scour computations including the d50. You should take some time to review the Hydraulic Reference Manual chapter on scour analysis. There may be another variable that is influencing your results more than the d50 size.