Re: Level

Chris N Deuchar wrote:
In article <qsudnd2x1c13FujZRVnyhw@xxxxxx>,
peter.jeanne@xxxxxxxxxxxxxxx says...

Interesting point here.
Were canals built with a gradient factored in or were they generally
designed level ?

Since they must be navigable with no water flow (ie no lock operation
and water only just at weir level) then for constant draught they
would need to be level. However, any water flow necessitates a
gradient, so then the top surface will no longer be parallel with the
level bottom discussed above. This implies that the bank height at the
upstream end should be higher than the lower end.

The gradient produced by flow is unlikely to remain constant because
the flow will be greater at narrows and immediately below locks being
emptied. There are also things like inertia to consider, wave effects,
friction, turbulent vs laminar flow.

I think that one of the most impressive feats of waterway engineering (for
its date) was the New River, built to supply London with fresh water. As
originally built it maintained a constant fall of five-and-a-half inches per
mile for the whole of its forty miles. Not bad for 1609-13!


--
Mike Stevens
nb Felis Catus III - currently at Brookwood
web-site www.mike-stevens.co.uk

No man is an island. So is Man.


.

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