Depth of water flowing in a $3\:m$ wide rectangular channel is $2\:m$. The channel carries a discharge of $12\:m^{3}/s$. Take $g = 9.8\; m/s^{2}$.

The bed width (in $m$) at contraction, which just causes the critical flow, is _____________ without changing the upstream water level. (round off to two decimal places)

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