Gardening for a wetter future

A practical guide to water harvesting and management for productive, natural gardening

Introducing the swale

A swale is a depression or ditch that follows the contour of the land like the lines used on topographical maps to illustrate elevation and gradient.

When seen from above the lone of the swale may curve across the surface of the land but when viewed edge on it will be perfectly horizontal and level.

Objectives

The primary objective of a swale is to intercept surface run-off that would otherwise be lost and retain it in the landscape. During rainfall events, once the soil is saturated, additional precipitation does not soak into the soil and instead 'spills' off the surface under the force of gravity and runs downhill perpendicular to the contour lines.

Place a swale in the path of the surface water and it is halted, spread sideways forming a long skinny 'pond'. From here the water slowly seeps into the ground, travelling much more slowly and remaining accessible to all the plant roots that it encounters along the way.

The swale therefore helps hold water from rainy periods, minimising surface run off and erosion and slowly releasing the stored moisture to plants located downhill.

Anatomy

  1. The swale line is laid out using the A-Frame and pegs

  2. Lay flattened cardboard (with any plastic and tape removed) on the downhill side and weigh down with branches

  3. Dirt is dug from the trench and piled on the downhill side. Use water to help identify and rectify lumps and hollows in the trench.

  4. Plant and mulch the moved soil.

 tags

swale  process  water  irrigation  how-to