QUESTION $2\mathrm{.}1$

i$)$ If the flow in a canal is sub critical explain the kind of flow and what happens as the canal gets narrower

ii$)$ If a channel is $4m$ wide with a slope of $0\mathrm{.}01$ and the Manning number is $0\mathrm{.}13$ and the channel depth is $1\mathrm{.}6m.$ What is the total flow in $m^3{S}^{-1}?$

iii$)$ Explain why is flow velocity measurement is of little use in accurate measurement of flow in an open channel?