What is a swale?
A swale is a large ditch or pan on contour (level). The dug out dirt, called "spoils," is placed downhill from the swale, effectively creating a dam to slow down the progression of water across the landscape. A swale can be as small or large as is dictated by the slope of the landscape.
- slows down water allowing it time to infiltrate into the soil, where it can be stored more effectively than above ground.
- slowed water allows sediment and soil to drop out, preserving topsoil and clears water for downstream habitats (fish spawning grounds).
- allows water to percolate into the root zone, feeding trees and plants. Trees and vegetation will in turn shade the ground, decreasing evaporation from the soil.
- this sets up a self-mulching system which builds soil at a rate up to five times faster than naturally occurs.
How to build
a swale? Take
this visual tour! (click on the any image to start)
Build them and watch them fill up. Over time they will infiltrate water fast and faster.
On a larger scale...
After the first few rains the swales begin to do what they do best...
...soak in the water, drop out the sediment keeping it from the salmon spawning grounds and recharging all the wells in the neighbor hood...