Simple methods of preventing soil erosion
Arid Land Information Network
To mark out a line on the contour, always start at the highest point of your field.
1. Push a small peg into the ground at the edge of the field and put one leg of the ‘A’frame
alongside the peg.
2. Next, move the other leg to the ‘A’ until the string hangs exactly over he painted mark.
Then push a peg into the ground alongside this leg of the ‘A’ frame.
3. The ‘A’ frame is then picked up and moved so that the first side is at the second peg and
the other leg is moved up and down until the string hangs centrally.
4. Continue across the field until the contour line is completed.
Line Level
(Nigel Walsh for Ethiopia)
Components
1. 2 "line level sticks".
2. 10 metres of good quality string approximately 2 mm diameter.
3. Builders line level
Construction
The line level sticks should be at least 1.2 m long and made from solid pieces of wood. The edge of
the sticks should be marked at 10 cm intervals. The string should be attached to both sticks at the
same height.
The line level is of a type normally used by builders and masons for checking the level of masonry
and consists of a metal tube 7.5 cm long, containing a spirit level and having a hook on either end,
so that it can be hooked on to a string.
Method
The line level needs 3-4 people to operate: one holding each of the two sticks with the "surveyor"
checking the bubble in the middle and possibly another carrying the pegs or markers. The first stick
is placed upright alongside the proposed starting point of the line and second operator walks across
the field until the line is tight. It is most important that the sticks are upright and the string is tight
(a length of 7-8 m is best). The surveyor then places the level in the center of the string, which
should be marked with a thread. He then instructs the second operator to move up or down the
field until the bubble is level. He should check that both sticks are upright and the string tight. A
peg is then placed to mark the spot and the first operator puts his stick against the new peg, while
the second operator walks on across the field. The process is repeated until the line is completed.
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