QUESTION $6$

HEC$-$RAS Set #$67-7-7$

A rectangular channel with a bottom width of $7m,$ a bottom slope of $0\mathrm{.}0018,$ and Manning's $n$ of $0\mathrm{.}024$ has a discharge of $67cms.$ A sluice gate

installed at the downstream end maintains a water depth of $7m$ just upstream of the gate. Compute the critical depth $(m)$ of the channel.

Enter the answer up to two decimal places $($like $3\mathrm{.}21)$ without unit.