Permaculture Designers Manual
CHAPTER 9 –
EARTH WORKING AND EARTH RESOURCES IN PERMACULTURE
Section 9.5 –
Levels and Leveling in Permaculture
Levels are taken to ensure that spillways work, drains run and houses sit level enough so that one can play at marbles without them all falling towards one corner.
There are tools of leveling, of which the most ancient and even the most reliable is that level assumed by the surface of water. One can always check a horizontal against the sea horizon or make sure a drain or gutter works by using a little water to flow down it.
Even sophisticated instruments like the theodolite use a bubble level to set up the base plate and then to check the telescope against this with its bubble before proceeding with tilt or swivel measures.
There are a few simple levels that can be handmade and are of great use to farmers and homeowners:
HOSE (“BUNYlP“) LEVEL.
A hose level can be made from easily-purchased materials, and is useful to survey some meters or even kilometers of diversion drain, level a house site from corner to corner or set a wall or spillway at a pre-determined level. The materials needed are (as put together as in Figure 9.6):
20m (65 feet) or so of clear plastic hose, diameter about 10 mm (1/2 inch);
2 corks or stoppers that fit into the ends of the clear plastic tube, each with a breather hole;
2 small cork balls that freely fit inside the clear plastic tube below the corks (optional);
2 stakes (2m or 6.5 feet), marked with the measurement of your choice (centimeters or inches);
Dessmakers’ tapes glued or screwed on to the stakes serve this purpose;
4 damps or tape to connect the clear hose to the stakes.
To prepare for use, uncork one end and fill the entire hose with water. Be sure all the bubbles are out of the hose; this is only certain with a completely clear hose.
Place both stakes together, tops level, on a piece of level concrete or wood. Keeping the stakes vertical, mark the water level in the clear tubes by unclamping and moving the measuring strips until the water level (or both cork floats) are at precisely the same measurement marked on the stakes. Re-cork the tubes.
In the field, one person walks past the other alternately, driving a stake every 6 or 15 m (20 or 50 feet) to guide diggers or machine operators, and allowing for the rise (or fall) of drains by allowing one cork ball to be an inch or so lower than the other at the next peg, moving the pole up or downhill to achieve this.
The stakes must be kept vertical when measuring.
1cm in 5m is 1:100 x 5 equals a 1:500 fall, ample for most diversion drains to carry runoff to dams. Dead level lines can also be run across landscape and dam walls checked for level or (If used for roads) a gentle rise.
I recently saw a 12km drain flowing gently all the way in sand at 1:2000, laid-in not by a skilled surveyor but by two women hired for a week and trained in 30 minutes on a hose level.
THE PLANE TABLE
The plane table is a sturdy tripod which can hold a U-shaped piece of plastic tube or glass, corked and de-bubbled as for the hose level, except this can now be swiveled about to sight in all directions (Figure 9.7 B). Lacking tubing, a bowl of water on which floats a piece of painted wood with two nails of equal length as “sights” will do (Figure 9.7 A).
Although Model B is self-leveling, it may be necessary to tap in one nail a bit on Model A by way of adjustment.
To check a plane table, set up two marked stakes (with easily-visible white masking tape) a little uphill from the point you will stand at, driving the tops to level using the table.
Viewing the stakes from Position B with the plane table, check that the level shows new level marks (b) to be exactly the same distance (d) below the stake tops (measure this).
One can then proceed to level, from Position B, anything that can be staked, painted, or nicked by another person. (Figure 9.8)
This is a very handy across-valley level to set in siphons or to find out where the outlet of a dam will send water by pipe and gravity flow or to see if a hill on which you want to place a tank at a distance is higher than your shower head at home.
Leveling need only be done once if done right. If in real doubt, buy a dumpy level or theodolite and read the instructions or if wealthy and incompetent, hire a surveyor (whose real job is mapping). Thousands of miles of drains have been surveyed, and levels set, by very simple tools.
Plane tables of various designs are used by surveyors, but these usually include a telescope for long distance work.
Ralph Long of Australia has devised a tractor mounted level which he has successfully used to cut drains, using the tractor itself as a check on levels. This is a bubble level which can also be fitted to any vehicle on farms and is called the Long Inclinometer (Permaculture Journal #22, 1985).
THE “A” FRAME:
This is made from two wooden or metal legs, nailed or welded firmly together at the apex, and fixed about two-thirds down their length by a welded or nailed and glued cross-piece. A plumb bob or weight hangs from a cord at the centre of the apex and a mark is made on the cross-piece at the cord line.
The “A” frame is then reversed and another mark made where the cord touches the cross-piece. The mid-point between the two marks is that point where the cord hangs when the feet of the frame level. (Figure 9.9)
In use, a person swivels the frame about one leg and sets in the second leg to the place where the cord hangs vertical. A peg is put in, temporarily, to judge where to place the next leg.