Knowing How to Build a Swale Is An Important Gardening Skill In Many Countries. It Needs To Be Better Understood In the UK.
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A swale is a simple, yet effective tool for water conservation and soil health. And in this article I’ll explain How to Build a Swale.
I’v e explained the purpose and benefits of swales in a previous swale article, check it out first if you want to understand why you might build a swale. If not, let’s [proceed and start at the beginning!
Planning and Preparation:
Site Selection: Choose a gently sloping area where you want to capture and divert water. Swales can also be built on level ground if it is fed by water from a higher level.
Soil Analysis: Understand your soil type to determine the best swale design. Clay soils may require deeper wider swales to allow for better infiltration.
Design: Determine the length, width, and depth of your swale. A general rule of thumb is to make the swale 3-4 times wider than it is deep.
Construction:
Mark the Contour: Use a level or a laser level to mark the contour line for the swale.
Dig the Swale: Use a shovel or other digging tool to excavate the swale, following the marked contour.
Shape the Swale: The bottom of the swale should be slightly concave to slow water flow and encourage infiltration.
Create a Berm/Bund : Build a small berm or bund on the downhill side of the swale to prevent water from spilling over. It needs to be level so that when the water does overflow it does so evenly across the full width .. a bit like a weir. Otherwise the bund will erode at the single point of egress.
Plant Vegetation: Plant native grasses, wildflowers, or other vegetation along the edges of the swale to stabilise the soil and maybe attract pollinators, depending on the species chosen.
Maintenance:
Regular Inspection: Check the swale regularly for any blockages or erosion.
Weed Control: Remove weeds that may compete with desired plants.
Repairs: If necessary, repair any damage to the swale, such as erosion or breaches in the berm.
Remember: The key to a successful swale is a gentle, meandering design that allows water to slow down and infiltrate the soil. Avoid steep slopes, as they can lead to erosion. By following these steps, you can create a valuable water conservation feature for your property.
In this article I have dealt with garden swales. But in some countries swales are built as a roadside feature to prevent stormwater entering water courses or sewage systems. Swales in this situation allow water to enter the groundwater reservoir. The image above is in a small French town in Normandy and takes rainwater from the adjacent car park. It has rocks at each end as both features and to slow water movement. New estates in this town are built with swales between the pavement and road. They have become a feature.
