Swales & Earthworks for Water Retention — FarmPal

Contour swales, berms, and keyline design capture and infiltrate rainwater into the landscape, recharging groundwater, preventing erosion, and creating lush productive zones even in dry climates.

Principles

  • Swales are level ditches on contour that capture and infiltrate runoff
  • Berms (mounds) downhill of swales are planted with trees and perennials
  • Keyline design uses subsoil plowing to move water from valleys to ridges
  • Water should be slowed, spread, and sunk never allowed to leave fast
  • Earthworks are permanent infrastructure design carefully before digging
  • A-frame level or laser level is essential for finding true contour

Action steps

  1. Map your contours

    Use an A-frame level (DIY from sticks and string) or laser level to mark contour lines across your slope. Flag every 10-20 vertical feet.

  2. Dig swales on contour

    Excavate a ditch 18-24" deep on the contour line. Place excavated soil on the downhill side to form a berm. Swale bottom must be perfectly level.

  3. Plant the berms

    Immediately plant berm with nitrogen-fixing trees and ground covers. Trees go on the berm, understory on the swale side, ground cover everywhere. Mulch heavily.

  4. Add overflow management

    Design spillways at swale ends to handle heavy rain safely. Overflow should flow to next swale below or to a pond. Never let swales breach uncontrolled.

Benefits

  • Recharges groundwater and raises water table
  • Eliminates erosion on slopes
  • Creates productive growing zones on berms
  • Drought-proofs trees and perennials
  • Can transform degraded land into productive forest

Further reading

  • The Resilient Farm and Homestead Ben Falk
  • Water for Every Farm (P.A. Yeomans Keyline)
  • Permaculture Earthworks Toby Hemenway courses