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Plot contour lines

Louis De Jaeger

31 mei 2024

Plot contour lines with A-frame, communicating vessels or laser

Measuring the contours of the area where you want to plant a food forest can be very useful in terms of your water plan. If you want this done very accurately, it is best to ask a surveyor, although there are costs associated with this. If you want to roll up your sleeves yourself, it is not very difficult to get started yourself. You just need some time, patience and basic working materials. You can find contour lines via the site , but these are a lot less accurate than if you determine them on the site yourself.

Determine the contour lines with an A-frame

You can easily assemble an A-frame yourself. This is what you need: 3 planks or sticks, a piece of rope, a marker and a weight. With the 3 planks you make an A-shape as shown in the illustration. Attach the string at the top. You hang the weight from this so that it extends beyond the horizontal plank. Mark the center on the horizontal plank. If your A-frame is now on a horizontal surface, the string will hang exactly in the middle. If the surface is not straight, the weight will move to the left or right. To work faster, you can also place a spirit level on the horizontal plank instead of working with the string.

To plot the contour lines, start at a fixed point and, as it were, walk with the A-frame through your future food forest. You leave one foot standing at a time and you pivot until the point where the string hangs in the middle. This means that both feet of the A-frame are on the same height line. After each step, push a (bamboo) stick or flag into the ground. When you reach the end of your terrain (or when you can no longer find a point that is the same height), you will see a line of sticks. This is your first contour line, congratulations! You now repeat this work every five to ten meters, depending on how accurately you want to work.

This is a very simple method for plotting contour lines. The disadvantage of this is that you have to make that rotation every time. Hence it can be interesting to work with the method of communicating vessels.

Communicating vessels to determine the contour lines

This is what you need to work with the principle of communicating vessels: a transparent tube of 5 to 10 meters long, water, a coloring agent (e.g. beetroot juice or food coloring) and 2 planks of 1.5 meters long. You draw two lines at both ends of the tube. Make sure you leave enough space for air so that you don't get any leaks.

You take the two planks and mark them every 10 centimeters. Mark these lines (0 cm, 10 cm, 20 cm). You now fill the tube in such a way that it reaches a height of 1 meter on both sides. Setting out is done in the same way as for the A-frame, although it is best to work in pairs here. The nice thing about this way is that you choose how big the steps you want to take are. This depends on the length of the clear tube. If you work with a 10-meter tube, you need to plot fewer highlights.

Easily lay out swales with the rotation laser and leveling bar

A-frames and communicating barrels are very nice low budget ways to get started yourself. If you want to work quickly and accurately, you can also opt to purchase or rent a rotation laser and leveling rod. You place the tripod with rotation laser at the zero point of your contour line. The rotation laser is a laser that rotates very quickly and therefore sends its signal all around. With the leveling bar, which has a receiver (light sensor), you look for the same heights by moving it each time. The closer you get to the same height, the longer the beep becomes. This way you can plot hectares of contour lines in no time.

Would you like to learn more about food forest design? Then read 'Design your own food forest' by Commensalist founder Louis De Jaeger or book a no-obligation phone call with one of our Commensalists.


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