Question

in a siphon aqueduct the most severe condition of uplift on the floor occurs when

Answer 1

Siphon aqueduct refers to the hydraulic composition in which an irrigation canal is passing over the drainage, however, the drainage water cannot pass clearly underneath the canal. In siphon aqueduct, the H.F.L of the drain is situated above the canal bed.  

In a siphon aqueduct, the most extreme condition of uplift on the floor takes place when the canal is dry, the drainage floor is at the H.F.L, and the water tables are at the H.F.L of the drainage flow.  

Answer 2

In a siphon aqueduct, the most severe condition of uplift on the floor occurs when the canal becomes dry and the water starts flowing heavily in it.

Under this condition, the HFL of the drain goes higher than the canal, which creates a symphonic action when water passes through the siphon.