Volume calculation for falling water

[oakleaf]

Hi,
I was hoping that I someone would be able to help me with a flow rate calculation that I am having trouble solving.
I am designing and building a resonable size vertical waterfall in a contemporary garden and obviously need exact (or at least sensible) flow rates to be able to allow for tank capacities and pump ratings.

Ideally the flow should be sufficient to have a good impact visually, but does not necessarily have to be a "sheet" of water. (Which I assume would require exponentially larger amount of water over the edge with an increasing face (fall) height.

I preview approx 200/250/300 cms fall down the face with a cascading "edge" of at least 400 centimetres.

In the event that this proves to costly / too noisy / otherwise unsuitable, then I would also be very happy to receive ideas as to the similar but different calculation required when the flow is attached to the face rather than in free fall. This I presume would be thinner and slower and therefore far less demanding in terms of pump capacity.

Help with this would be much appreciated.

JH

 

[RWF7437]

Try calculating your waterfall as a broad crested weir. You can find some of the formulae in King's Handbook of Hydraulics. You can also experiment and come up with rating curves of your own.

Good luck