At the site of the Syphon aqueduct, the drainage bed is generally depressed and provided with a PUCCA floor.
On the upstream side, the drainage bed may be joined to the PUCCA floor by a vertical drop (when a drop is of the order of 1.0 m or less) or by a glacis of 3:1 (when a drop is more than 1m).
The downstream using the slope should not be steeper than 5:1
