Terra-Forming For Water Resiliency
We have had a long-term dramatic impact on the landscape the scale of which is not fully recognised. Early hunter-gatherer societies burned off vast expanses of vegetation in fragile landscapes where complex plant communities had evolved over thousands of years and had adapted to sporadic rainfall - which was largely supported from the transpiration of those plants.
Once the vegetation was removed by fire - the landscape was laid bare to the sterilising intensity of the sunlight and erosion of what soil had accumulated by wind and water. This resulted in large areas turning into deserts long before the first civilisations arose. Since the time of agriculture and development of cities - people have further cleared, simplified and disrupted the hydrological cycle of plants and soil that had developed over millennia to soak and store water into the landscape and support life.
Permaculture design aims to reverse some of this trend - by harnessing technologies and strategies to slow, store and spread water in the landscape cover soil with vegetation and mulch and support the biological processes in soil responsible for building soil carbon and health.
Often the first part of this strategy is terra-forming the landscape - to change the dynamics of water movement and to slow it down and store it as much as possible. This has the beneficial result of making water more available in the soil to support life and also to avoid the erosive impact of water moving quickly across the surface (and taking precious soil with it).
Once the vegetation was removed by fire - the landscape was laid bare to the sterilising intensity of the sunlight and erosion of what soil had accumulated by wind and water. This resulted in large areas turning into deserts long before the first civilisations arose. Since the time of agriculture and development of cities - people have further cleared, simplified and disrupted the hydrological cycle of plants and soil that had developed over millennia to soak and store water into the landscape and support life.
Permaculture design aims to reverse some of this trend - by harnessing technologies and strategies to slow, store and spread water in the landscape cover soil with vegetation and mulch and support the biological processes in soil responsible for building soil carbon and health.
Often the first part of this strategy is terra-forming the landscape - to change the dynamics of water movement and to slow it down and store it as much as possible. This has the beneficial result of making water more available in the soil to support life and also to avoid the erosive impact of water moving quickly across the surface (and taking precious soil with it).
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Case Examples
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Swales
A swale is a ditch dug out along a contour line, which capture the water that is flowing downhill and diverts it along that contour line within the swale. The swale can be filled with gravel or mulch to avoid evaporation and on the downhill berm side - a planting of diverse perennial trees is often established (supported by the infiltration of water from the swale in to the soil). This strategy is often used to establish lines of trees along swale lines - which can then be used as a way to divide up a grazing system into different paddocks, provide more shade to soil, provide additional yields and support building soil ecology.
The swale can therefore act as a first step in a catalyst of events that restores a landscape to greater diversity and more healthy function.
The swale can therefore act as a first step in a catalyst of events that restores a landscape to greater diversity and more healthy function.
Keyline Design
Keyline design is a method incorporating the Yeoman's plow (pulled behind a tractor) to create a series of tears in the soil/subsoil to redirect the flow of water across the landscape. This redirection to to move water flowing from ridge to gullies of a contoured landscape in the reverse direction. This is achieved by starting the plowline from the gully (uphill) to the ridge (at a downhill location). Thus using gravity to redirect the natural tendency of water to flow from ridges to gullies.
This is often achieved by mapping the landscape in CAD software (or similar). setting up the plowlines and then feeding that information to tractors (which can steer themselves using this data and re-create the designed pattern).
This method is most often used in broadacre, rolling, pastoral landscapes which suffer from a shortage of rainfall (hence popularised in Australia).
Adaptation of this method have involved setting up a seat above the plow - so that a planter can drop trees into the plow line created. This can be further enhanced by inoculating the soil with micro-organism rich compost during the planting process (although this slows down the process and requires frequent topping up of supplies due to limited space to store materials on the back of a tractor rigged with a plow).
This is often achieved by mapping the landscape in CAD software (or similar). setting up the plowlines and then feeding that information to tractors (which can steer themselves using this data and re-create the designed pattern).
This method is most often used in broadacre, rolling, pastoral landscapes which suffer from a shortage of rainfall (hence popularised in Australia).
Adaptation of this method have involved setting up a seat above the plow - so that a planter can drop trees into the plow line created. This can be further enhanced by inoculating the soil with micro-organism rich compost during the planting process (although this slows down the process and requires frequent topping up of supplies due to limited space to store materials on the back of a tractor rigged with a plow).
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