Relationship between bed and wall roughness coefficient of uniform flow in smooth flume

Based on the friction partition theory (Einstein 1942) and affections of breadth depth ratio on roughness(Knight 2002), the relationship between bed and wall roughness coefficient is researched though 28m flume experiment. The measured water level agree with the calculated one which supposed n = n
b
= n
w
. And it proves that bed roughness coefficient equal to wall roughness coefficient while the rectangle flume is made of same material in acceptable precision.