Consider a rectangular channel cross section. For a given discharge, Q$,$ and channel width $($b$),$ it is possible to solve the Manning equation for depth, y$.$

$($Note: The nonlinear equation is not directly invertible for y; use your calculator, Excel solver, or other numerical tool to solve.$)$

A$.$ For width $($b$)$ of $2,4,6,8,10,$ and $15$ ft $,$ find the depth $($y$)$ corresponding to Q$=100$cfs$.$ The channel is unfinished concrete. Longitudinal slope is $0\mathrm{.}001.$ Complete the table below:

B$.$ The best hydraulic section is defined as the cross$-$section of the specified shape $($rectangle$,$ in this case$)$ that gives the minimum wetted perimeter for a given discharge. Determine the value of y$/$b for the best hydraulic section. What do you observe about the best hydraulic section and velocity?