A channel with flow depth $=3\mathrm{.}0$m$,$ bed width $=20$m$,1$:$1($V:H$)$ side slopes and gravel bed of d $=40$mm$.$ $=40$o and critical shear stress is $0\mathrm{.}97$gyS$.$ Channel must be kept stable.

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Find:$($a$)$ Maximum permissible channel slope

$($b$)$ Maximum permissible discharge

$($c$)$ Definition of $$stable$$

$($d$)$ How would you decide if the channel will actually be stable or not?

$($e$)$ What could you do to make sure the channel is stable if it is not currently stable?

$($f$)$ What is the disadvantage$($s$)$ of your proposed method in Part $($e$)$ above?