permaculture

["Darren Doherty" <darren@permaculture.biz>]

G'day,

I developed a technique last year during the Keyline Design Course at
Tuscon, Arizona for making a contour map using cheap available
materials....one of our students didn't have the cash to get a surveyor to
do the job on his 40 acres...so I came up with this solution on the
whiteboard and have since tested it on the ground quite a few times now...

1. Using a Bunyip/Water Level, A Frame, Laser Level or Dumpy/Automatic Level
mark out a contour line using stakes or pin markers
2. Using a Bunyip/Water Level, Laser Level or Dumpy/Automatic Level go down
or up the desired elevation (eg. 1 foot or 0.5m)
3. Repeat in sequence steps 1 & 2
4. Using a consumable GPS (I have a Garmin Etrex VistaC - about $200 worth)
record waypoints at each of the stakes. Be sure to wait for the GPS to
'settle down' reducing its error. Hold the GPS out in front of you over the
stake and then take the waypoint.
5. Using a measuring wheel (or paces if your good!) take some 'ground
truthing' measurements across the site. This will be useful later when you
want to rough out the 'coefficient of error' from the GPS as there will
always be with a consumable model....Good enough for a bush job though!
6. Then load the GPS data onto computer...most GPS units come with a basic
mapping programs or you can (as I do) use a program like MapInfo, other GIS
or CAD programs. The way points will come up marking the pattern of the
contours. You can then join the dots and presto you have your contour
map....you can also record the boundary fences and other features of the
site using the GPS to give you your contoured feature plan.

I have just done one of these yesterday....the results of which can be found
at:
http://picasaweb.google.com/permaculture.biz/Dalpura/photo#5234877346927198562.
For this job I only needed a few contours. The accuracy came in at
between
1-3m which over 20 acres is fine....

All the best,

Darren

-- 
Hooroo,
Darren J. Doherty

Australia Felix Permaculture
Broadacre Permaculture Design & Development
International Certified Permaculture Education

Web: http://www.permaculture.biz
PhotoLog: http://picasaweb.google.com/permaculture.biz
Blog: http://www.australiafelixpermaculture.blogspot.com/

+61 (3) 9010 6220
skype: permaculture.biz

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