Keyline Design and Geographic Information System Analysis

Keyline design is a relatively new concept to those located outside of Australia although its origins have ties to the American dust bowl of the 1930s. Originally developed in the 1940s and 1950s by P.A. Yeoman on his farmland in Australia, this system of rainwater storage and gravity-fed irrigation is a method that provides long-term water security, conservation of soil through prevention of soil erosion, and sustainability of agricultural systems.

Yeoman developed the system based on his own experiments and on some of the methods recommended by the Soil Conservation Services of America (now known as the U.S. Natural Resources Conservation Service); a federal agency that was created to help conserve farmland and soil following the Dust Bowl ecological disaster.

Keyline design is a broad based land management system that uses the concept of permaculture to use the natural contours of the land to site, and to build, an interconnected network of ponds and canals to efficiently store water, irrigate the landscape, and recharge groundwater resources. The “keypoint” to the system is a point where water tends to collect and drains into a canal, a tributary system or a water storage pond. The “keyline” is water course that tracks the elevation of the keypoints.

Yeoman spent years understanding how rainwater, elevation, slope, aspect, and vegetation all effected water drainage and how slight changes in those systems could enhance water conservation. Modern farmers now have access to technology that can significantly reduce the amount of time spent observing and mapping the landscape.

Geographic models can easily be generated with the use of satellite and aerial imagery, Digital Elevation Models (DEM), and Geographic Information Systems (GIS) which can greatly increase the effectiveness and scale of keyline design. Much of this data is already available through local and government agencies but supplemental mapping work can easily be performed with the use of a professional grade GPS or Total Station.

GIS in particular is a very powerful cartographic analysis tool that can provide optimal locations to design and build keylines and keypoints of the system. Watershed models can be created based on existing topographic and hydrologic datasets and these can be combined with soil type and vegetation datasets to provide an overall map and design plan for an optimal permaculture system utilizing keyline design.

The disadvantage to the use of GIS is that it is a highly specialized computer system that, due to the cost and training required to operate, is generally only available to companies and government agencies. However, for the United States, most of the required data is available free online from the U.S. Natural Resources Conservation Service (NRCS) and the NRCS offers several conservation programs, data, and maps available to farmers and ranchers to promote sustainable practices.

Perhaps a polite phone call to a NRCS GIS professional may help you produce a keyline hydrologic analysis of your property. -KATHY FAIRCHILD

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