292 Sustainable Farming
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The next step in preparing to build contour barriers
is finding the contour lines.
➊ At the top of the slope where you want
the first barrier, place your A-frame so it
goes across the hill, not uphill or downhill. Put
one leg of the A-frame where you want the contour
line to start. Move the other leg of the A-frame until the
plumb line hangs over the center mark. The contour is where
the feet of the A-frame are when the plumb line is on the center mark.
➋ Put a stake next to the second leg of the A-frame.
➌ Turn the A-frame to find the next level place across the hill, and repeat the first step.
Continue to the end of the field or slope, marking every 2 meters with a stake.
➍ Move to the next place you want a barrier
(10 to 20 meters downhill) and repeat the process.
➎ When you finish marking every contour line,
stand at one end of each line and look at the
line of stakes. Notice if each contour line
is an even curve or not. You may need
to move some of the stakes a little
to make an even curve.
Contour lines marked with stakes
Guidelines for building contour barriers
Once contour lines are measured and marked, and as you decide what kind of
barriers are best for your land, keep these general guidelines in mind:
• Preserve or plant trees and plants. If the slope is very steep, the trees
already growing there or trees you plant will protect it from collapsing.
Grasses and plants with strong roots will help to hold soil and water.
• Slow down water, but keep it moving. It is important to keep water
moving, whether down the slope or into the soil. Poorly planned barriers
can lead to standing water, which lets mosquitoes breed and spread
malaria and other illnesses.
• Fix problems as soon as they happen. Heavy storms may cause a contour
trench to collapse or a wall to break. Fix it right away to prevent further
erosion.
• Start from the top. Water runs downhill. By starting at the top, you
protect everything below, and can use many small barriers.
A Community Guide to Environmental Health 2012