Building Swales and Contour Beds to Slow and Sink Rainwater

ByStephen Albert

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Swales and contour beds are powerful tools that slow, capture, and infiltrate rainwater into the soil rather than letting it run off. These techniques prevent erosion, improve soil moisture, and build resilient, fertile gardens. Managing water on the landscape is essential to regenerative gardening.

Over years of gardening in Sonoma Valley, I’ve used swales along gentle slopes and contour beds in raised areas to create pockets of water storage, feeding plants naturally while reducing the need for supplemental irrigation.

Why Use Swales and Contour Beds

  • Reduce Erosion: Slows water flow on slopes, protecting soil.
  • Capture Rainwater: Stores water where plants need it most.
  • Increase Soil Fertility: Water infiltration supports microbes and plant roots.
  • Support Plant Growth: Keeps soil consistently moist without overwatering.
  • Enhance Resilience: Prepares gardens for heavy rainfall and drought.

How to Build Swales

  1. Locate Contours: Use a line level, A-frame level, or string level to find natural contour lines on your slope.
  2. Dig a Shallow Trench: Follow the contour, typically 12–24 inches deep depending on slope and rainfall.
  3. Pile the Soil on the Downhill Side: This creates a berm where plants can be grown.
  4. Plant on the Berm and Trench: Use deep-rooted plants, cover crops, or trees to stabilize soil.
  5. Check Flow: Direct runoff into swales and ensure overflow paths are safe.

How to Build Contour Beds

  • Follow Natural Contours: Shape raised beds to follow slope lines, creating ridges and swales between them.
  • Add Mulch and Compost: Protect soil, retain water, and feed soil microbes.
  • Plant Strategically: Place water-loving or heavy-feeding crops along the lower side to take advantage of moisture collection.

Tips from My Garden

I’ve built swales along gentle slopes and shaped raised beds to capture rainwater in vegetable gardens. Berms planted with comfrey, clover, and perennial herbs retain water while building soil fertility. Observing water flow during storms helps me adjust placement and slope for maximum capture and minimal erosion.

Swales and Contour Beds Basics

TechniquePurposeQuick Tips
SwalesSlow water, capture rain, reduce erosionDig along contour, pile soil downhill to create berm, plant stabilizing crops
Contour BedsMaximize water infiltration on slopesShape beds along contours, mulch, plant water-loving crops downhill
Soil & MulchRetain water, feed microbesTopdress with compost and organic mulch
PlantingStabilize soil, absorb waterDeep-rooted plants, cover crops, perennials
ObservationOptimize designWatch water flow during storms, adjust slopes and swales

Conclusion

Swales and contour beds are simple, effective regenerative tools for managing rainwater. By slowing and sinking water into the soil, you reduce erosion, build fertility, and create resilient gardens that thrive through both droughts and heavy rains.

Swales & Contour Beds Cheat Sheet: Capture Rainwater and Build Soil

Why Use Swales and Contour Beds

  • Slow water flow on slopes
  • Capture and store rainwater for plants
  • Reduce erosion and runoff
  • Improve soil moisture and fertility
  • Support resilient, productive gardens

Key Techniques & Tips

TechniquePurposeQuick Tips
SwalesSlow water, capture rain, prevent erosionDig shallow trenches along contour lines; pile soil downhill to create berms; plant stabilizing crops
Contour BedsMaximize water infiltration on slopesShape raised beds along natural contours; mulch; plant water-loving crops downhill
Soil & MulchRetain water, feed soil microbesAdd compost and organic mulch to trenches and berms
PlantingStabilize soil, absorb waterUse deep-rooted plants, cover crops, and perennials on berms and trench edges
ObservationOptimize water captureWatch flow during storms; adjust trench depth, berm height, and placement as needed

Garden Tips

  • Use a line level or A-frame to mark contours accurately.
  • Combine swales with cover crops or perennials for added fertility.
  • Mulch heavily to reduce evaporation and protect soil structure.
  • Start small—one swale or a few contour beds—and expand as you refine technique.

Regenerative Gardening Learning Hub

🌿 Start here: The Complete Guide to Regenerative Gardening and Farming

1️⃣ Soil Health and Living Systems

2️⃣ Biodiversity and Polyculture

3️⃣ Carbon Sequestration and Organic Matter

4️⃣ Water Stewardship

5️⃣ Perennial Crops and Permanent Systems

6️⃣ Animal Integration

7️⃣ Human and Community Connection

8️⃣ Regenerative Design and Planning

9️⃣ Inputs and Outputs: Closing the Loop

10️⃣ Case Studies and Personal Experience

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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