defining keypoint

April Sampson-Kelly askpv at
Fri Jun 19 21:34:05 EDT 1998

I remember reading your definition concave to convex and
I myself had been using it up to then too.
Then I saw Yeomans JNR's retort and his disapproval of concave - convex
and realised the whole matter is harder to define than ever.
I have a lot of discussion from student in my permaculture course
that the permaculture definitions in Mollisons books (concave to convex)
doesn't fit with the Yeomans latest edition (which Yeomans JNR has
noted some math errors BTW)
Apart from paying for an expensive course with Yeomans and having to pay
copyright licencing fees for the information I gain, I feel like I'll
have to re-invent the wheel.
MY present position from your and Yeomans JNR recent comments is
"steepness of the valley floor suddenly rises"
COMMENTS please.

> -----Original Message-----
> From: owner-permaculture at
> [mailto:owner-permaculture at]On Behalf Of Australia
> Felix
> Sent: Wednesday, 17 June 1998 9:18
> To: permaculture at
> Subject: Re: Water for Your farm(P.A. Yeomans) and Centuar design
> Hello People,
> Good to see some discussion going on with regard to Keyline. We have been
> playing around with and applying the concept for about five years
> now - only
> we do not call it Keyline, as it is a trademark of Ken B. Yeomans
> of Keyline
> Designs (, but Centaur Design (without the copyright
> restriction). We picked up this name from an farm planning/agroforestry
> consultant called Bill Sharp down in South Western Victoria in South East
> Australia. Calling it this from a commercial perspective does not
> impinge on
> Mr. Yeomans trademark or business name (Keyline Designs). In addition it
> serves as perhaps a greater definition of the pattern in the
> landscape that
> the line of cultivation, diversion of irrigation drains take, as they
> resemble the two horns of a centaur. With us in permaculture (also a
> trademark - however more available term to use through a well known
> education system) the use of centaur design has been applied to just about
> every one of the 535 odd properties we have worked on. See our web page
> ( for some pictures with many more
> available where
> requested in html/gif format).
> With respect to placement of dams (as we call them) we try to
> place them as
> high in the landscape as is practical ie. according to storage ratio (too
> great a slope means we have to push too much dirt to get an
> effective hole);
> depth to rock; soil textural characteristics (although sometimes
> this can be
> amended by the use of different amendments eg. gypsum for dispersive
> soils.); catchment potential (improved by diversion drains).
> It is wise to start with some sort of plan. Aerial photos with
> superimposed
> layers of topographic information (contours) as those provided by
> us (in PC
> MapInfo based format) or by others such a Mr K. Yeomans (similar
> medium only
> using digital terrain modelling), or with clear acetate layers
> (D.I.Y.) are
> a good start so that potential dam sites can be located according to need.
> All of the keyline books always directed that topographical planning was a
> necessary part of the process.
> As for the location of keypoints there has always been a great deal of
> confusion/dicussion as to their exact location. At a very
> unofficial keyline
> course run by ex-students of PA Yeomans that I attended in 1994 the same
> question was on everyone's lips. Some of the "official" definitions and
> references are as follows:
> "The highest valley water conservation site is generally just below the
> keypoint of the primary valley, thus leaving perhaps less than 20% of the
> slope above the keypoint."
> "...Now the keypoints of the adjacent primary valleys in a common
> watershed
> such as a secondary valley are higher as the land rises. The
> primary valleys
> themselves form in the main ridge, so that normally as the
> country rises the
> heads of the adjacent valleys are higher and the keypoints of the valleys
> are higher. In a series of primary valleys flowing into a larger valley or
> into a larger valley or into a creek, in country of a uniform geological
> formation, the keypoints of the valleys generally have this rising
> relationship to each other."
> The Challenge of Landscape, PA Yeomans, 1958.
> .....This first slope of a primary valley is steeper in relation
> the second
> longer and flatter valley slope. I named the point of change in the two
> slopes of the primary valley, the Keypoint of the valley, and a
> contour line
> from this point and in both directions in the valley, the Keyline of the
> valley. The name Keyline, coined to describe this contour, has
> been given to
> the full system of land development."
> Water for Every Farm, 2nd Edition, PA Yeomans, 1968
> "...The Keypoint of the valley is the point of change in the two
> slopes of a
> primary valley, and a contour line from this point and in both directions
> within the valley is the Keyline of the valley. It is worth
> emphasising that
> the Keyline does not extend onto the ridge at all. A Keyline only
> exists as
> a feature of a primary valley."
> Water for Every Farm, 3rd Edition, PA Yeomans, KB Yeomans ed., 1993
> (available from )
> " I named the point of slope-change in the primary valley the Keypoint. A
> contour line around and across the valley from side to side through this
> point is the Keyline of the valley. ONLY A PRIMARY VALLEY HAS A KEYLINE. "
> The City Forest - The Keyline plan for the Human Environment
> Revolution, PA
> Yeomans, 1971
> I wrote a couple of articles on the subject a few years ago in a national
> farming magazine giving my thoughts on the location of the keypoint and
> therefore the keyline. I wrote thereabouts that:
>  ..."the keypoint is the point of change in a primary gully where the
> landshape changes from concave to convex..."
> (related diagrams can be provided upon request)
> We have installed a few lock pipes in larger dams (20-120 Ml - Megalitre)
> that we have constructed as the economy of scale warrants them.
> Depending on
> the depth of the dam wall and the materials (galvanised steel,
> flexible low
> density polyethylene pipe - LDPE) used they can be cost between AUD$ 100 -
> 1000 +. Given the cost of dam construction using a Cat D6 - 7 is
> around AUD
> $1000-$1400/day (with generally 1Ml a machine/day) it can be out of reach
> for a lot of people. In addition a lot of earthmovers find their placement
> annoying during construction due to the lack of manoeverability
> available in
> smaller dams. Where they are put a couple of 44 gallon drums are placed
> upended over old fencing iron star pickets protecting the pipe ends from
> damage. The pipe must have baffles placed along the length of the pipe to
> prevent tunnelling of water along the pipe caused by
> condensation, which can
> cause the dam wall to fail or leak over time. The soil around the
> pipe must
> also be lightly rammed with some sort of crow bar or similar
> device to seat
> the pipe and keep it in place. Baffles can be made from a variety
> of durable
> materials although must be constructed so that they can be fixed
> rigidly to
> the pipe. I have seen some use silicone which they have used as
> an adhesive
> for the top and bottom baffle plates quite effectively, but would probably
> not suit engineers amongst us....
> Alternatives that our clients have used to lockpipes (especially on
> reconstructed or existing dams) are syphon pipes that work pretty well as
> long as the syphon is not lost...In addition to this (even on some flatter
> Centaur-type properties I've seen) pumps of different capacities
> are used to
> put water into a channel for flood irrigation of the ground below them.
> The most widespread use of the method that we apply however is on the
> ground, where we are using a single aspect of the concept to keep
> and evenly
> distribute rain where it falls (Keyline is an integrated concept that is
> best applied using the wholeness of its application for best results). The
> method that we use is called pattern cultivation, or pattern/parallel
> plowing (see our web page for some pictures). Its dreadfully
> easy. We simply
> with our Yeomans Keyline Plow on the back of the tractor drive a line that
> from a ridge goes slightly 'up' or rises into the adjacent gully, and then
> go 'down' or slightly fall into the next ridge. Once you have done this
> across a paddock then you turn around and run parallel to this
> first line of
> cultivation and repeat until you have plowed the whole paddock. Geoff
> Wallace put it in Permaculture Two very well indeed:
> "Even a child can keep a machine travelling slightly downhill"
> We've used this style of cultivation and in a large range of applications
> and for many different crops and layouts with fantastic results. Examples
> include: Soil Renovation for broadscale pasture and cropping; Determining
> and creating layouts for commercial/domestic Vineyards, Forestry, Olives,
> Orchards and other tree crops in high and low rainfall areas
> (150mm - 1800mm
> pa). I often say that there is a certain beauty to functional
> landscapes and
> with this layout this is certainly the case.
> Anyway I hope that this answers some of your questions. I could
> rave on all
> day about this sort of stuff and the work we have done but time is always
> the killer....Again let me know if you need some photos sent of a
> particular
> subject as we have plenty that I haven't put on the web page.
> Also I will be coming to the US sometime later this year designing a
> property and would be glad to catch up after that - a bit of study touring
> never hurt anyone.
> Cheers,
> Yours and Growing,
> Darren J. Doherty

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