$(13$ marks$)($a$)$ Calculate the normal $($or uniform$)$ depth, yo$,$ for a flow rate of $50$ m$3/$s in a

rectangular channel of width B of $20$ m if the Manning$$s n of the channel is $0\mathrm{.}03$ and its slope

is $0\mathrm{.}0016.$

Use Excel and goal seek to solve for this flow depth, showing a screenshot of your

spreadsheet with annotations showing what equation is in each cell similar to the

recordings shown on Canvas.

$($b$)$ Is the channel on a mild or steep slope?