Swales mitigate stormwater runoff.
Swales are way easier than catching rain in a tank or barrel.
Swales are more efficient than tanks or barrels.
Swales build self-sustaining ecosystems.
Let’s elaborate on each of those points.
1. SWALES MITIGATE STORMWATER RUNOFF.
Stormwater runoff is a huge problem in most cities. Water is seen as a liability (flooding) so the modern mindset is that we need to send it away as fast as possible. This has resulted in horrible breaches of environmental stewardship every time it rains, when we send 13 million gallons of raw sewage into local waterways each year in my city alone, because the overtaxed sewer system combines stormwater with sewage during heavy rain events.
Stormwater is a problem that only governments, institutions, and experts can solve. In reality, there would be no problem at all when we citizens take part.
For example, a 1200 square-foot house catches 30,525 gallons of rain from the roof each year. How much water does your roof collect? Captureing 75% of that, or almost 22,900 gallons in our landscape. What if we all caught tens of thousands of gallons of water in the landscape–assuming a site assessment proves a swale to be feasible?
2. SWALES ARE WAY MORE EFFICIENT THAN TANKS.
Good soil is thirsty. Organic matter acts like a sponge, easily holding several times its weight in water. Three quarts of dry soil can easily hold one quart of water. When we translate that to the soil in our yard, if our yards were covered in one foot deep of rich, moist soil, it would hold as much water as a 3-inch-deep lake the size of the yard. It would be cost-prohibitive to install a container that could catch that much water. But the soil will hold it for free.
Here are a couple of other strategies that will maximize the benefit of a swale by minimizing evaporation and your time in the garden:
add organic matter (compost) and mulch to your swale berms regularly
shade the soil on swale berms with dense plantings
3. SWALES BUILD SELF-SUSTAINING ECOSYSTEMS
Swales catch water and direct it to where it’s needed, which is in the soil. Instead of water running off or pooling above ground, swales direct it downward into an underground reservoir.
Nature has its own built-in, self-regulating system. When water is needed, it is naturally released. No work on our part after the swale is built!
This underground reservoir attracts microorganisms. Suddenly the soil is alive and the “micro herds” begin eating and pooping and procreating (perhaps not in that order) and voila–we’re generating organic matter and fertilizer right in the place where we need it.
This means fewer inputs, which saves you money and time. The more the organic matter builds, the more moisture it holds. With more organic matter, the system can better withstand both floods and droughts.
As the water reservoir and nutrients in the soil build, gardening will become a breeze for you.
ARS Landscape Materials & Supply, Denver, Colorado