A rectangular stream channel is $300ft$ wide and carries a flow of $15,000cfs.$ The depth of flow is $10ft.$ 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 $)$ for bridge lengths $($B$)$ of

$250ft,200ft,150ft,100ft$ and $50ft.$