Consider water flow through two identical channels with square$/$rectangle flow sections of $\backslash (4\mathrm{.}500\backslash$mathrm$\{$~m$\}\backslash$times $4\backslash$mathrm$\{$~m$\}\backslash ).$ Now the two channels are combined, forming a $\backslash (9\mathrm{.}00-\backslash$mathrm$\{$m$\}\backslash )-$wide channel. The flow rate is adjusted so that the flow depth remains constant at $4$ m $.$ Determine the percent increase in flow rate as a result of combining the channels.

The percent increase in flow rate as a result of combining the channels is