permaculture

[David Muhl <dmuhl65@yahoo.com>]

Neil,

As far as rainfall data for your area, I'm not sure where you are located, 
but in the U.S. these would be good places to look:

1) Municipal/county engineering departments
2) Your respective State DOT (dept. of transportation)
3) The NRCS (National Resource Conservation Service)

For major flood protection, most designers use the 100 year/24 hour storm.

For minor conveyance systems/swales, they use 10 year/24 hour storm totals.

Pay attention to "Peak Rate of Flow" in addition to storm totals when sizing 
conveyance systems.

In any book or online resource, you should research "Manning's Formula" for 
use in your calculations.  There are more items to consider than I can list 
in this post.  Hope this is of use!

David

--- On Wed, 2/16/11, Neil Bertrando <neilbertrando@gmail.com> wrote:

> From: Neil Bertrando <neilbertrando@gmail.com>
> Subject: [permaculture] sizing spillways
> To: "permaculture" <permaculture@lists.ibiblio.org>
> Date: Wednesday, February 16, 2011, 8:54 AM
> Hi all,
> 
> I'm looking at my methods and wanting to ensure due
> diligence, so I'm asking
> for suggestions and some details on how to size spillways
> correctly,
> estimate or find records on max events, etc.
> 
> Can you recommend some sources for this info?
> 
> or share some equations for calculating the size of a
> spillway based on Rate
> of Discharge.
> 
> Also, if there are differences between sizing spillways for
> swales vs. check
> dams, vs. earthen dams/ponds or other water harvesting
> structures, those
> details would be very helpful as well.
> 
> Thanks,
> Neil
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