Earthworks: Erosion Control and Much, Much More

Earthworks are used to prevent water from running across a landscape, i.e. swales, diversions, grassed waterways, terracing and contouring, etc.[1] They are contoured sections of the land that trap and hold water for later use or slow absorption into the earth, and minimize erosion of soil.

Sediment from erosion of soil from agricultural lands, logging, construction and other activities that disturb the soil and leave it exposed to rainfall is the largest pollutant by volume of U.S. surface water.  The biggest contribution is from agricultural land, which loses an average of 10 tons/acres/year. [2]

Earthworks are ideal for dealing with erosion problems and provide strategies for stabilizing and increasing water available water on site.

• Scallops: A half circle berm that extends all the way across the hill.  This can be eyeballed and done by hand and is good for smaller scale.  Better to use swales if larger scale erosion problem exists.
• Swales: Long, level ditches, aligned perpendicular to the water flow that trap and hold water and sediment.
• Grassed Waterways: Use vegetation in natural waterways to slow down water that is moving too fast, in order to increase water absorption.
• Check Dams:  Brush and rock that you find from a gulley and put on contour.  When it rains, silt and sediment loads up on there and then will eventually fill up. Check dams are also used like a mini swale.
• Fashee (width of a pencil) and Live Stake (1-2” in diameter): These are pounded into the earth where you have made your check damn to encourage sprouts growing right out of your check damn.  Good for stream bank problems because sprouts will mature into trees and shrubs, depending on which stake is used. Alder, red oshur, and black willow are the three most common woods used for this.  Made by soaking for 12-24 hours to release a natural growth hormone. For alder, soak first in the black willow.
• Terracing: Cutting the natural slope of the hillside into steps that can be planted.
• On Contour Strip Farming: Curved strips planted with corn, alfalfa, clover, and soybeans, with rotation of crops from year to year.
• Diversions: Channels used to direct water across the landscape.  Used to slow water and move it to where it is needed most.

Earthworks are one of the best ways to increase the amount of water held within the landscape.  When used in a garden they can diminish our susceptibility to drought, and can be especially useful in places that have become desertified by bringing more water back to the land.   We will use earthworks extensively at the center and in our communities to catch water during the wet season for use later in the dry season.