What you’ll need?

  • Big sheet of paper and a drawing pen or computer drawing software
  • Google Earth desktop version

Estimated time: 1h

STEP 1:Determine the growing area’s slope steepness

Look at a topographic map of your site and its contour lines to determine how steep the slope is across the whole growing area of interest. Use a Google Earth Elevation Profile tool for a quick check-up.

Note that you can only install swales on gently to moderately sloped land (0° to 20°) with less than 3:1 ratio (not more than 1 foot of drop over a 3-foot run). Any steeper than this and you risk blowout from too much water buildup, overflow, and soil destabilization.

–>Action step: Find a set of desirable contour lines outlining suitable terrain for swales.

STEP 2: Mark the first reference contour on your map

It’s good practice to install your first swale at the highest point of your land. This is a very important principle of harvesting water, as this way you slow the flow as soon as possible and manage water coming in from offsite.

–>Action Step: Look at a contour map to find the longest contour line at the highest possible elevation. Use this line for your initial swale.

Note: Where you begin and end your swale is entirely up to you. In most cases, the restrictions of the surrounding landscape (access, property boundary, fencing, etc.) will be your guide.

STEP 3: Decide on the distance between the swales

If you’re planning on having more than one swale, you’ll need to determine how far apart to make them. This will depend on your site goals and rainfall and runoff conditions, but the overarching rule of thumb is: the greater the runoff, the closer swales should be spaced.

For example, on steep, overgrazed or disturbed land, you will be confronted with large volumes of fast-moving sediment-laden water in intense rainfalls so you should place your swales at close intervals.

 On gentle slopes covered with thick native grass, the watershed can absorb more rainfall before significant runoff begins so you’ll need fewer, and more widely spaced, swales.

Also, the swales should be more closely spaced at the top of a hill than toward the bottom, as the top of a hill is the driest part of the landscape that drains more rapidly, and thus needs more rehydration.

–>Action step: Decide on the distance between the swales

STEP 4: Create the final layout

Now,  mark the remaining swales.

–>Action Step: Based on the desired distance, mark the remaining swales, going down the slope from the initial swale.

Now you have a final food forest layout with swales.

Finally, think through how the newly created swales relate to the existing main access points. Define where you’re going to locate pathways that enter the newly created growing areas between the swales.



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