A rectangular stream channel is $100m$ wide and carries a flow of $50m\frac{3}{s}.$ The depth of flow is $0\mathrm{.}5m.$ A bridge

with symmetric embankments is to be constructed over the channel. Without considering head losses,

determine the depth of flow in the constriction $(y2)$ and upstream of the bridge $(y3)$ for bridge lengths $($B$)$ of

$90m,80m,70m,60m$ and $50m.$