A $3-$foot diameter circular channel has a flow rate of $8\mathrm{.}8$ cfs $,$ with a flow depth of ${15}^{\text{'}\text{'}}.$ Is the flow subcritical or supercritical? Using the relationship given, find the critical depth for the channel. For circular channels: $y_c=[\frac{1\mathrm{.}01}{D^{0\mathrm{.}26}}][\frac{Q^2}{g}{]}^{0\mathrm{.}25}$