$8\mathrm{.}3\mathrm{.}8$ Suppose the $30-$min unit hydrograph for a watershed is

$\backslash$table$[[$Time $($hr$),0,3,6,9,12,15,18,21],[UH(\frac{m^3}{s}\frac{?}{cm}),0,15,45,65,50,25,10,0]]$

$($a$)$ Determine the $1-$hr unit hydrograph.

$($b$)$ A storm has a total depth of $4cm$ with an effective rainfall hyetograph of $2cm$ in the first $2hr,1cm$ in the second $2hr.$ Assuming the baseflow is $10\frac{m^3}{s},$ calculate the total runoff hydrograph from the storm.