On Fig, a rectangular channel has a width of $30\mathrm{.}0ft$ and a bed slope of $1$:$12,100.$ The normal depth is $6ft.$ A dam across the river elevates the water surface and produces a depth of $9\mathrm{.}8ft$ just upstream of the dam. Develop a spreadsheet with the standard step method and plot the backwater profile with $n=0\mathrm{.}025.$

Solve Problem $7$ fig, by using the direct step method.

Solve Example $10\mathrm{.}1$ with $y_0=12ft$ and $S_0=1$:$1,500.$

Solve Example $10\mathrm{.}2$ with $n=0\mathrm{.}035.$