Canal Design and Silt Theories

In Lacey's regime theory, the regime channel bed slope is given by $S = \frac{f^{5/3}}{3340 Q^{1/6}}$. For silt factor $f = 1.0$ and design discharge $Q = 64\text{ m}^3/\text{s}$ (so $Q^{1/6} = (64)^{1/6} = 2.0$), the bed slope $S$ is $\frac{1}{K}$. The value of $K$ is: