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Keyline Design

Keyline Design. What is Keyline? . Design strategy for passive rainwater harvesting and use developed in 1950s in Australia by P.A. Yeomans Influenced development of Permaculture and is highly compatible and integrated with Permaculture methodology

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Keyline Design

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  1. Keyline Design

  2. What is Keyline? • Design strategy for passive rainwater harvesting and use developed in 1950s in Australia by P.A. Yeomans • Influenced development of Permaculture and is highly compatible and integrated with Permaculture methodology • For the broadscale landscape level, but principles work down to any small scale

  3. Understanding Contour (Maps) • Level: flat lines at right angle to slope, curving as slope changes, around valleys and ridges. • Where water will not flow – water flows at 90 degrees to contour. • Same height apart (intervals) • Surface distance apart changes depending on slope • Each given a height above “datum” – usually sea level, but can be any other fixed point. Valley floor

  4. Contour in a landscape

  5. Creating a new landscape pattern for water flow • Make/ facilitate/ allow water to do its duties: Passive (gravity powered) and Positive impact • Patterns to details: putting it all together in an integrated strategy • Plan the slowest longest route for water through your system • Always give water a way out/ onward (or it will find its own!) = water moved by gravity

  6. What do we need to do with rainwater? SSS: Slow it! Spread it! Sink it! WHY?

  7. No SSS • High runoff and erosion • Uneven distribution (space and time): Boggy areas + dry areas, floods + droughts • High evaporation, low infiltration and low recharge of groundwater (wells and spring s dry up)

  8. With SSS • Low runoff, soil conservation and soil creation • More even distribution: Even hydration of landscape and plant growth possible throughout more of year • Low evaporation,, high infiltration and groundwater recharge (new springs form) HOW?

  9. Keypoint and Keyline (plan view) • The Keypointmarks a change in relationship between the valley and its adjacent ridges (shoulders). • Keypoint is usually around where contour lines in a valley first start to become further apart (can be slightly above or below). • Keyline is a level (or slightly sloping) line taken around all slopes from the keypoint Valley floor Above keyline, the valley is narrower and steeper than its shoulders Below keyline, valley is wider and less steep than its shoulders

  10. Keypoint (side view) • Usually on or just below point where slope turns from convex to concave Water runs faster so material is eroded Convex erosional slope Water runs slower so material is deposited Concave depositional slope Earthworks are much easier on concave slopes!

  11. Earthworks on slopes • Aim to harvest as much water as we can, while moving as little earth as we can. Dam walls less stable Convex/ erosional slope Dam walls more stable Concave/ depositional slope • To harvest the same amount of water, on concave slopes we need to move less earth. • The keypoint and the keyline is the highest point in the landscape where we can easily make dams

  12. Some landscapes are not obviously concave or convex Break point = where slope goes from shallow to steep and erosion begins

  13. Ridges and Valleys • Slopes are convex and concave vertically AND horizontally: we call these ridges and valleys. • There are usually several within a single rainwater catchment area, or “watershed”. Valleys Ridges Keyline Therefore keypoint valley dams are in the highest, most concave slopes we can find. Why do we want them as high up as possible?

  14. Watershed = a distinct rainwater catchment area • Main ridges divide separate watersheds • Primary ridges and valleys divide the watershed • Each valley keypoint has its own keyline • Usually we start from the valley with the highest keypoint or the biggest catchment Which one is that?

  15. Keyline Earthworks 1: Channels Keyline swales • Catch surface runoff water and fill up, soaking it in and evenly spreading it out. • Prevent runoff concentrating in the valleys. • Can also overflow into and fill dams. Keyline Diversion Drains • Off-contour swales leading slightly downhill. • Can be away from keypoint, to direct water out of valleys and towards ridges to rehydrate ridges… • …or towards keypoint dams.

  16. Swales on-contour

  17. Off-contour Swale…

  18. …aka diversion drains

  19. Keyline Earthworks 2: Plowing • Keyline Cultivation • Rip-plowing slightly off-contour downhill away from keypoint to rehydrate ridges, which are then easier to replant. • NOT inversion plowing • Only done once, or with a second plow after a few years – not regular plowing. • Like hundreds or thousands of very small absorbent swales, preventing rainfall from concentrating in the valley . • Water and organic matter fall into the rips and is absorbed into the soil.

  20. Keyline plowing • Helps to decompact soil and break hardpans • Allows water, organic matter and roots to enter deeper into the subsoil • Brings life into lower soil areas, turning it into living topsoil • Increases soil water retention capacity and self-fertility of soil (from beneficial microbes)

  21. Keyline plowing pattern • First step of reconditioning slopes • Can be followed by reforestation or controlled grazing (high herd density, short time)

  22. Keyline Earthworks 3: Dams Keypoint Dam • Where possible and practical, dams are constructed on the Keyline in valleys, connected by a gently falling diversion swales/ drains to carry water to the dams and send overflow on to the next one. • If used in a series, no spillway is built, and the overflow goes down the swale and into the next dam. • Irrigation swale below dam

  23. Can also just use a siphon

  24. Keyline Irrigation

  25. The construction of a Keyline dam will often cost considerably less than a pump and engine installed for spray irrigation. The Keyline dam, its pipe and valve outlet, will operate the same sprays with no pumping cost. “New pasture being irrigated by gravity pressure on "Nevallan“ farm. Guideline timber strip forms a permanent marker for Keyline cultivation. The truck in the centre background is travelling along our Keyline road”.

  26. The Keyline often determines our land use on slopes

  27. Other Dams We can build dams on any site given enough material resources, but we should be careful to get best output for our input and consider: • Earth type • Slope steepness • Downstream safety of houses and structures • Height above use points • Available catchment or diversions

  28. Saddle Dam • Usually the highest available decent sites in the landscape • Can be fully excavated below ground or walled in from either side. • Can have horns or extensions at either end, and connect to diversion swales/ drains.

  29. Ridgepoint dam • Another way to get water higher up in the landscape (than keypoint). • More effort for less water, but that water might be VERY useful – depends on your design context.

  30. Contour Dam • For the gentler, lower slopes

  31. Flatland dams or “Earth Tanks”

  32. Other Things to Remember… • Roads • Design to catch their water and use to fill dams • Houses • Never under dams! • Forestry, Agroforestry, Agricultural systems – crops and animals. It is usually convenient and good practice from most other viewpoints, to locate the homestead and all farm buildings and their attendant roads in the higher country. From the point of view of full Keyline development, it becomes a part of planning to do so, in order to secure abundant run-off water to fill the Keyline dams from these sources.

  33. Which order to work in?

  34. Keyline Scale of Permanence Checklist • Climate • Landform • Water • Access/Circulation • Vegetation and Wildlife • Microclimate • Buildings and Infrastructure • Zones of Use • Soil Fertility and Management • Aesthetics/Experience of Place [Adapted from P.A. Yeomans by David Jacke]. We can address things in this order of priority and conduct design work and practical work in this order (but not rigidly!)

  35. 1) Climate • plant hardiness zone • predicted future climate change status • annual precipitation • seasonal distribution • latitude • wind directions • prevailing, seasonal variations, storm wind directions • growing degree days (important for ripening nuts) • average frost-free dates • chilling hours (important for fruit tree dormancy) • extreme weather potential: drought, flood, hurricane, tornado, fire • heating/cooling degree days

  36. 2)Landform • slope (steepness, rise/run in percent) • topographic position (i.e., mid-slope, hill crest, valley floor, etc.) • bedrock geology: permeability, depth, nutrient content, acidity • surficial geology: type of parent material, permeability, depth, stoniness, • nutrient content, acidity, suitability for various uses, etc. • estimated seasonal high water table depth • estimated depth to bedrock, hardpan or impermeable layers of soil • elevation • landslide potential

  37. 3) Water • existing sources of supply: location, quantity, quality, dependability, sustainability, • network layout and features (spigots, pipes, filters, etc.) • watershed boundaries and flow patterns: concentration and dispersion areas, including • roof runoff patterns, gutters and down spouts • potential pollution sources: road runoff, chemical runoff from neighbors, etc. • flooding, ponding and puddling areas • possible sources of supply: location, quantity, quality, dependability, sustainability, cost • to develop • location of all on-site and nearby off-site culverts, wells, water lines, sewage lines, • septic systems, old wells, etc. • erosion: existing and potential areas

  38. 4) Access/ Circulation • activity nodes, storage areas • pedestrian, cart and vehicle access points, current and potential patterns • materials flows: mulch, compost, produce, firewood, laundry, etc.

  39. 5) Vegetation and Wildlife • existing plant species: locations, sizes, quantities, patterns, uses, poisonous, • invasiveness, weediness, what they indicate about site conditions, etc. • ecosystem architecture: layers and their density, patterning and diversity, resultant • habitat conditions, light/shade, character, quality • habitat types, food/water/shelter availability

  40. 6)Microclimate • define various microclimate spaces • slope aspects (direction slopes face relative to sun) • sun/shade patterns • cold air drainage and frost pockets • soil moisture patterns • precipitation patterns • local wind patterns

  41. 7)Buildings and Infrastructure • building size, shape, locations doors and windows, exist. and possible functions • permanent pavement and snow piles from plowing it • power lines (above and below ground) and electric outlets • outdoor water faucet, septic system, well locations • location of underground pipes: water and sewer line, footing drain, floor drain and down • spout drain lines, tile drains, culverts, other • fences and gateways

  42. 8) Zones of Use • property lines, easements, rights-of-way • existing zones of land and water use • well protection zones, environmental and other legal limits (e.g. wetlands regulations, • zoning regulations, building setbacks) • current uses by neighbors and passersby • use history and impacts on land, current or future uses

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