I said above that survey methods must be quick, reliable,
and easy. If these criteria are
not met, there is no way that we will transfer the capacity of surveying on to
the communities that we are working with.
This means that expensive GPS equipment is out.
Here are a few low-tech survey tools that we have borrowed
from books and fit to our purposes.
The first is an A-frame:
A-frames are extremely simple; they can be made with tree
branches, a piece of string, and a rock.
Poor farmers in many developing countries use A-frames to make terraces
in their fields. In 2009 a colleague made an aluminum
A-frame for surveying the slope of a planned 700-meter pipeline. It worked wonderfully.
Next is a fluid communicating vessel:
I found the idea for this survey tool in a FAO
publication. Whereas the A-frame
is great for leveling and carefully measuring slope 1 meter at a time, we
needed that would cover ground faster without losing accuracy. What you see is two 2-meter boards with
rulers and a clear hose running the full height of them. The hose runs between the two boards,
with slack, and a 5-meter chain links the bottom of the boards. To use this, the boards are stood
upright and water is dripped into them until they’re even at 1-meter height of
water. Then the surveying is as
simple as taking water readings from both the front and the rear sticks, every
5 meters. Crunch the numbers as
you go or when you’re done, and you can quickly draw a line graph of the
slope. I was very pleased with how
well this worked.
I don’t have a picture of the 3rd surveying
technology I want to share with you, but I can describe it easily enough!
For surveying long stretches, nothing beats the simplicity
of a small spirit level that clips onto a string! In any hardware shop here we can find small plastic spirit
levels, no bigger than your finder, and they clip onto a tightly held
string. Two people take the ends
of that string, stretch it out for up to 20 meters, find level, and measure the
difference. It’s not as accurate
as the former two methods, but it’s a great tool for when you just need to make
sure that a long ditch (over 1 kilometer) is still going downhill!
There you have it, 3 surveying tools that can be built for
under $10. One for short and super-accurate
work, another for medium distance and detail, and the last for longer distances. When used right, these provide
communities with the information they need to see their options and make their
action plans.