Allyn River Permaculture

Permaculture demonstration farm in the Hunter Valley, NSW, Australia

Permaculture is a design system and philosophy that emulates the patterns in nature to holistically and sustainably integrate the physical and social needs of people and the ecosystem.

surveying workshop

Permaculture workshop on Basic Surveying

For a Permaculture designer understanding the landscape, be able to read and interpret topographical maps and other survey information is an obvious prerequisite in the preparation of meaningful design.

It is equally important for the designer to be able to carry out basic surveying tasks with confidence, I suggest, any boundary survey work or full site level preparation may be left to a licensed surveyor as their use of modern electronic survey equipment and direct computer analysis and drawing preparation makes their work very economical.

Understanding levels and the nomenclature associated with survey plans and maps is also a prerequisite for successful site planning and earth working. To be able to direct other consultants and contractors during the construction of permaculture projects and understand the lingo is also important

In fact understanding the landscape, particularly reading and understanding what you are looking at on topographical maps is dependent on the understanding of ‘levels’.

The most critical item in permaculture water management systems is the use of contour in establishing swales, spillways, contour ploughing etc. For keyline ploughing using a Yeomans Plow the contour is just as important so the ploughing can be accurately ‘off’ contour.

Contour is defined as a line drawn on a horizontal surface that connects points of the same level (altitude). This is generally a height above sea level.

AHD Australian Height Datum, if noted on survey drawings and topographical maps allows all levels to comparable and relating to the same datum point, zero is the mean sea level set at a number of points around Australia.

The bottom part of the diagram shows some contour lines with a straight line running through the location of the maximum value. The curve at the top represents the values along that straight line.

As illustrated by the diagram understanding contours allows the reader to visualise the landform, ie. The closer the contours are together the steeper slope.

( If the above diagram did not include the cross section, reading the contour plan would not allow the reader to know whether they were looking at a mound or a depression. It is always necessary to include some numeric reference. )

The following is part of a topographical map which is based on a contour plan with other landform information.

Typical topographical map

It is also important to be familiar with the detailed legend on topographical maps, refer attachmet to this document.

Types of Surveys

There are many types of Surveys, the most relevant to Permaculture designers would be topographical surveys which identify levels and locate land features trees etc

Other categories which may require a registered surveyor due to some legislative implications are property surveys, identifying boundary lines, property corners, rights of ways, easements, and calculating property areas.

Survey techniques

The techniques used for surveying and land measurement are dependant apon the expertise and equipment available.

The basis of this workshop is some explanation of techniques available from the simple, ancient and cheap to obtain through to modern electronic equipment used by our professional surveyors.

A Frame Level

The ‘A’ frame is probably the most primitive, cheapest and simplistic technique but still highly accurate level.

Mother Nature is right all the time. Use the force of gravity and a simple A-frame level to tell you when something is level. The Egyptians used these to build many of their structures.

This simple level will give you an accurate, level plane every time as long as you calibrate it accurately from the start and you construct the A frame so it is rigid. So that the location of the plumb bob will not change.

To make the frame build an triangular frame

To construct’ screw together two equal length pieces of timber, (could be any rigid material), Mark a line across both pieces at approx ¼ of the length from the loose end. Fix a cross piece to each leg at the mark. The length of the cross piece should be approx 50% of the leg length.

Suspend a plumb bob from the top fixing to hang below the cross piece.

Place the frame on a level area and mark the plumb bob location. (on an accurately made frame this should coincide with the centre).

Laying out a contour using an A frame

To use swivel the frame about one leg until bob hangs over the centre mark. Place a stake or mark the spot of both legs, then swing the frame about one leg and repeat the process. Continue across the landscape as required.

The frames could be made to any size to suit the project.

‘A’ frame made from tomato stakes

Water level   ( Brickies level or Bunyip )

The water tube level is straightforward to use, like the A frame it is a primitive levelling tool and is also suitable in third world countries  where farmers can be quickly taught to layout contours. The concept itself – of matching up levels of water – is especially easy to understand. Advantages of the water tube level are that it can be operated by one person. ( assuming one end is fixed in position).

The length of tube is theoretically unlimited, it is physical handling that restricts is length.

Clear plastic tubing (10mm diam) is firmly attached to the poles, with securing devices. The ends of the tube should be about 10 cm from the top of each staff and the bottom fixing point about 20 cm from the bottom of each staff.

The tube is then filled with coloured water until the water level is about halfway up each staff. It is essential that no air bubbles are trapped in the tube and, if necessary, they can be removed by tapping with the finger. Wherever the two staves are set, the free water surfaces in each tube will be at the same level.

Laying out a contour using a water level

The two staves are placed back to back at the starting point. After any air bubbles have been removed and the water has come to rest, a mark is made on both staves, indicating the water level.

One end can then be secured to a stake. The other staff can then be moved in what seems to be the direction of the contour line for the required distance. The staff can then be moved slowly up and down the slope until it is in a position where the water level in the tube coincides with the mark. The staff is then at a position where the ground level’s the same the starting point. A second peg or mark can be placed at this point. This procedure continues as required.

Simple Line Level

The line level is another simple surveying instrument, particularly when there is a team of people available for the work. It is simple to operate and is easier to transport than other similar surveying tools such as the A-frame. It is especially quick and very accurate when used properly. However a line level does require three people to operate it.

A line level consists of two poles, between which a length of string is suspended. A spirit level is hung on the string. The level is the type used by builders, but has small hooks at either end.

The poles should be of even height (about 1.5 m) and the string (about 2 mm in diameter) and precisely 8 metres in length. A notch is made in each pole at exactly the same height (say 1.4 m above ground level) and the ends of the string tied around these notches.

The centre of the string (4 m from each end) is marked and the level itself is suspended there.

Laying out a contour

The poles are held apart by operators with the string extended and the spirit level positioned exactly in the middle of the string. When the bubble in the level is between the two marks this means that the poles are positioned on level points on the land – in other words on the contour. The poles must be held vertically.

The process is similar to the A frame, by levelling the first points and stepping across the landscape.

Dumpy Level

The Dumpy is the first modern surveying instrument and is based on a telescope mounted on a level base, so that it remains at the same level when rotated. Dumpys have developed considerable with time with easier mountings and improved optics particularly adjusting the clarity and normal image.

A dumpy level has an eyepiece, bullseye spirit level and 3 levelling screws as well as a focus for the telescope lens  and generally the base has a 360 degree compass, for laying out,

Start by attaching the dumpy level to the legs and tighten the baseplate screw.

Next turn the dumpy so it is parallel with two of the levelling screws. Turn both screws either away from each other or towards each other simultaneously until the bubble in the spirit level is centralised.

Now turn the dumpy 90 degrees so the level now points towards the levelling screw that has not been touched and then use this to complete the bubble levelling by putting the bubble in the middle of the bulls-eye.

This should now result in the dumpy being perfectly level, which is very important, before you start to take spot heights.

Take the staff and place on the temporary bench mark or bench mark and rotate

the dumpy, focus the crosshairs using the eyepiece focus to suit your eye and then focus the instrument on the staff. You read off where the two large cross hairs meet.

So in this example your reading would be 0.96 metre or 960 millimetres.

Each ‘block’ represents ten millimetres   Each E represents 50 millimetres

Each 100 millimetre section alternates back and forth and finally, on some staffs

the colour alternates between black and red for each metre.

Laser level

The laser level operates on all the same basic levelling principles as above, however the optical device is replaced by a rotating laser beam. The main advantage is that it can be operated by one person and multiple people ( with separate receivers ) can work off the same head.

The laser beam representing the collimation axis rotates 360o around the unit and can extend for 300 to 500 metres.

This rotating laser beam takes the place of a person having to sight through the telescope of an optical level in order to record a level along the collimation axis.

The laser beam representing the collimation axis is received by a sensor that can be attached to the levelling staff.

This sensor is able to slide up and down the levelling staff and an audible tone is heard to indicate how close to the collimation axis the sensor is. When the sensor is moved toward the collimation axis the intermittent tone will increase in frequency, until a constant tone is heard when the sensor and axis are at the same height. Many instruments will provide a different sounding tone, to indicate the direction of travel required.

A digital screen on the receiver sensor allows the operator to visually see direction arrows that indicate the direction the sensor needs to travel in order to be at the same height as the collimation axis. When the exact elevation is reached, the display will also indicate this using a straight line with no direction arrows. Other information such as battery status and levels of accuracy are also displayed.

The instrument is relatively self levelling. That is, it is set up on a tripod and adjusted so that it is reasonably level, and once switched on, will automatically adjust to reflect a level collimation axis.

Laser levelling equipment can also be installed onto excavation plant such as dozers and graders. This enables the plant operator to determine the required levels of excavation or grading without stopping the machine and getting out to observe readings. The audible tone simply indicates the proximity to the required level and remains constant when level is reached.

TheodoliteA theodolite is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a key tool in surveying and engineering work, particularly on inaccessible ground. A modern theodolite consists of a movable telescope mounted within two perpendicular axes—the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision,

Digital Theodlites

In digital teodolites the reading out of angkes is automatic and displayed visually on screen.

Total StationA total station is a combination of an digital theodolite, an electronic distance meter (EDM) and software running on an internal (or external) computer known as a data collector.

With a total station the operator can determine angles and distances from the instrument to points to be surveyed. With the aid of trigonometry and triangulation, the angles and distances may be used to calculate the coordinates of actual positions (X, Y, and Z or northing, easting and elevation) of surveyed points, or the position of the instrument from known points, in absolute terms.

The data may be downloaded from the total station to a personal computer and with the aid of software, will generate a map/plan of the surveyed area.

Today total stations also have a GPS interface which combines these two technologies to make use of the advantages of both (GPS – line of sight not required between measured points).

Measurement of distance is accomplished with a modulated microwave or infrared carrier signal, generated by a small solid-state emitter within the instrument’s optical path, and bounced off of the object to be measured.