A wide channel terminates in to a sudden fall. The channel conveys a specific discharge of 4.2 /s/m and has a bed slope of 16 cm/km. Assuming that the depth of flow at the fall is equal to the...

A wide channel terminates in to a sudden fall. The channel conveys a specific discharge of 4.2
/s/m and has a bed slope of 16 cm/km. Assuming that the depth of flow at the fall is equal to the critical depth and the Manning rough ness coefficient is 0.022, find the length of the water surface profile ahead of the fall.