In$-$class gradually$-$varied flow problem $($subcritical$)$

A grouted$-$riprap, trapezoidal channel $\backslash ((\backslash$mathrm$\{$n$\}=0\mathrm{.}0252)\backslash )$ with a bottom width of $\backslash (4[\backslash$mathrm$\{$~m$\}\backslash )]$ and side slopes of $\backslash (\backslash$mathrm$\{$m$\}=1\backslash )$ carries a discharge $12\mathrm{.}5[$cms$]$ on a $0\mathrm{.}001$ slope. Compute the backwater curve $($upstream water surface profile$)$ created by a low dam that backs water up to a depth of $2[$m$]$ immediately behind the dam.

$1$ Numeric $1$ point

What is the water depth in $[$m$]$ at a distance of $1000[$m$]$ upstream of the dam?

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$1\mathrm{.}70$

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$2$

What is the water surface elevation in $[$m$]$ at a distance $1000[$m$]$ upstream of the dam? $($Assume here that the elevation of the channel bottom is $0[$m$]$ at the dam$).$

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$2\mathrm{.}70$

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$3$

At what distance upstream of the dam does the water depth fall within $\backslash (1\backslash \%\backslash )$ of the normal depth $($i$.$e$.\backslash (0\mathrm{.}99$ h$\_\{$n$\}$