[Robert A Cook PE]

I couldn’t measure it - but if the “canal” across the ground and tile pipes inside the aquedcts were kept clean, it wouoldn’t need to be much of a drop.

[Little Bill]

A what if, if the syphons that you observed had a venturii effect would this have scoured the system? I am curious, having never had a close up, because I did some waste treatment work when I was a kid and flow/velocity was a maintenance concern.