Water for Your farm(P.A. Yeomans) and Centuar design

Australia Felix pcorgbgo at bendigo.net.au
Tue Jun 16 19:18:28 EDT 1998


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 (www.keyline.com.au), 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
(www.australiafelix.com.au) 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 www.keyline.com.au )

" 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






More information about the permaculture mailing list