Design the most efficient $($straight$)$ lined trapezoidal channel to carry $30m\frac{3}{s}$ on a longitudinal slope of $0\mathrm{.}2\%.$ The lining of the channel is to be float$-$finished concrete. To do this you will need to assume best hydraulic section and to determine the minimum total depth of the channel including freeboard $(d=y+F),$ the bottom width and the side slope.