Using Permaculture Earthworks to Capture Rainwater Runoff and Prevent Erosion (PVP018)

 

“You don’t impose a solution.  You arrive at a solution.”Larry Santoyo







What do you do with 350,000 gallons of rainwater runoff that enters your property with a high velocity causing erosion? 

One option is to harvest that water, slow it down, and take away the erosion by constructing some permaculture earthworks. 

Alden Hough of the Sky Mountain Institute joins me to talk about some earthworks that were constructed on his 7 acre property last March during a Paul Wheaton earthworks workshop.  He will also talk about some of the upcoming events at the 2013 Fall San Diego Permaculture Convergence that will expand these earthworks.

Joey Delia of Evoke Hope and Tipuana Farm also joins the conversation to talk about the plant systems that were put in place after the earthworks construction.

During the workshop last March we constructed a pond and a long swale to capture the 350,000 gallons of storm water that were running off of the road onto Alden’s property, causing a lot of erosion in the process.

The dam was constructed at the highest part of the property allowing Alden to gravity feed the water down-slope and zig zag the water across and down the property through a series of swales decreasing its erosive qualities and hydrating the landscape in the process.

The earthworks have turned the problem (high velocity, high volume water) into a solution; providing water to grow native habit and food in a winter rainfall area, where water isn’t cheap.

 

Key Takeaways from this Episode:

  • Choose the option that is most appropriate for your situation and needs.  There isn’t a single correct way to do any of this.  Assess you own situation and needs and then apply the appropriate solution. 
  • Observe the site and design based off of that.   Don’t immediately assume that you have to construct earthworks.  Take some time to observe the site and how elements like water react on the site.  Then design based upon those observations and what you want to achieve.
  • Swales are primarily a tree growing system used to harvest overland flow.   If you don’t want to grow trees and you don’t have runoff, then swales might not be the most appropriate solution.  Think grazing operations.  If you can achieve 100% water absorption in the soil, then a swale probably isn’t needed.
  • Slow it, spread it, sink it.  Three things that you can do to control erosion caused by moving water.
  • Use the moisture gradient in swales to determine where your plant species go.  In general species that like wetter roots get planted down-slope of the swale and plants that like drier roots get planted on the swale mound or even the up-slope side of the swale.
  • Look to create quick shade over your swales with fast growing species.  This will help to slow water loss.
  • Not everything that you build is going to work like you expected it to.  Try to make the best of the situation and adapt the design to turn what is actually happening into a positive.
  • Plan for historic rain events.  Always have a safe route for excess water to exit your system in the case of a above average rain event.
  • Look to native species first.  If you can find a native species that can fulfill your needs then choose it before bringing in an exotic species that fulfills the same functions.  The native species will be adapted to local climates and pollinators.  You will also be supporting other local species that use that native.

 

The pond. Empty.

The pond. Empty.

A view looking down the swale and finger.

A view looking down the swale and finger.

 

1402403_597186336985987_1762275809_o

Source: Whole Systems Design LLC

A brief explanation of making swales: this is how to slow, spread, and sink all of the water that was flowing across your landscape INTO the landscape, leaving you with enhanced plant growth and leaving the watershed with less runoff to deal with during storms. Illustration and pages from The Resilient Farm and Homestead

 

Geoff Lawton explaining the swale plume:

 

Darren Doherty explaining his home farm water harvesting system:

Darren Doherty talking about swales versus Keyline plowing:

 

For more information on the Alden:

To contact Alden with any questions you can reach him at permaculture@skymountain.org.


Support Permaculture Voices

You can support Permaculture Voices through a one time or reoccurring donation at permaculturevoices.com/support


Can't get enough permaculture?
Get 23 free audio presentations from PV1.
In depth information on farming and permaculture presented by Joel Salatin, Mark Shepard, Geoff Lawton, Toby Hemenway, and many more. Sign up and get the presentations right away.

Did you get some value out of this post? If so, then please take a second to support Diego on Patreon!

Leave a Reply

Your email address will not be published. Required fields are marked *