Rainwater Harvesting, Vol 2, Earthworks by Brad Lancaster
Eight Principles of Successful Rainwater Harvesting
- Begin with long and thoughtful observation.
- Start at the top of your watershed and work your way down.
- Start and simple.
- Slow, spread, and infiltrate the flow of water.
- Always plan an overflow route, and manage that overflow as a resource.
- Create a living space.
- Do more than just harvest water.
- Continually reassess your system.
Berm and Basin (aka swale)
- Use on land sloped up to 18 degrees.
- Use native perennial vegetation.
- Variations: contour berm, boomerang berm, net and pan
Terrace
- Used on steep land.
- With or without retaining wall.
French Drain
- Directs stormwater quickly into subsoil.
- Only with sediment-free water, directly off roof, etc.
Infiltration Basin
- Collect rainwater for trees and vegetation.
- Plan for peak overflow.
- Sunken garden beds.
Imprinting
- Create micro-climates for seed germination and growth.
- Use mechanical imprinter for more than 1 acre.
Mulch
- Benefits: increase rainwater infiltration, improve soil fertility, reduce evaporative loss, limit soil erosion, suppress weed growth.
- Variations: vertical mulch.
Permeable Paving
- Replace large areas of concrete with permeable pavers, gravel, etc.
- Increases infiltration and reduces rainwater runoff and erosion.
Diversion Swale
- Swale built slightly off-contour.
- Gradually diverts rainwater away.
- Slows, diverts, and promotes infiltration.
- Variation: spreader drain
Check Dam
- Slows, spreads, and infiltrates ephemeral watercourses during heavy rain.
- Use on eroding arroyos, gullies, below culverts, near roads/paths.
- Variations: loose rock check dams, wire-encased rock gabions, brush check dam, one rock check dam.
Vegetation
- Critical component of all earthworks.
- Plant in or beside all earthworks, always.