What is the relation between alternate depths in rectangular open channels?

Answer 1

(2(y1)^2(y2)^2)/(y1+y2)=(yc)^3

y1=depth at start of the channel

y2=depth at end of the channel

yc=critical depth

Answer 2

In rectangular open channels, alternate depths refer to two different water depths that the flow can take within the channel. These depths are symmetrically positioned about the channel bottom and are a result of the conservation of energy in the flow. The alternate depths occur when the flow transitions between supercritical and subcritical flow conditions within the channel.