I would like to create a sediment transport model. I was looking the Hydraulic Reference Manual in particular the Van Rijn’s fall velocity (page 12-31). I watched the formel 12-49 w=((s-1)*g*d)/(18v), however I have already found the same formel but w=((s-1)*g*d)^2/(18v) in other books, I mean the numerator is raised to 2.