Swales – level ditches dug to follow the contours of the land – are one of the principal ingredients of permaculture earthworks which are, by and large, recipes for catching and holding rainwater runoff and encouraging it to slowly infiltrate the soil rather than being lost to the nearest river. Because they’re level, swales don’t channel the water away but hold it in situ until it soaks into the soil. They can be dug to any sort of scale and used alone or, as part of an integrated water catchment system over an entire property, in combination with other elements like ponds, infiltration basins and dams.
On narrow terraces and steep mountain slopes with thin soils – ie. here – swales are not something you can use on a large scale, but they can still be useful. When I dug the lower ponds, the effect on the ability of the surrounding soil to support abundant growth was immediate and impressive, but it didn’t extend too far along the terrace. Just 2 metres away the soil was so dry in summer it barely supported a few grasses and wildflowers and would turn to dust in your hand and blow away. So after working out the contours of the terrace, I decided to extend the area of hydration much further along by using the ponds to feed small swales.