A rectangular stream channel is $70m$ wide and carries a

flow of $0\mathrm{.}4\frac{m^3}{s}.$ The depth of flow is $3m.$ A bridge with

symmetric embankments is to be constructed over the

channel. Without considering head losses, determine the

depth of flow in the constriction $($y$2)$ and upstream of the

bridge $($y$3)$ for bridge lengths $($B$)$ of $70m,50m,$ and

$30$m$.(1$ pt$)$