Maps: how to procure them, read them, and use them

Treasure Lake GIS Map

Treasure Lake GIS Map, 2ft (60 cm) contour map

Written by Doug Crouch

The creation of maps through utilizing available technologies while leveraging these resources speed and aid our design work tremendously.  They are used to develop spatial relationships and help to explain the element of time, space, and energy circulation despite this static form.  They can be alive with colors, graphics, symbols, and tools for explaining the undercurrents of a design (i.e. Sectors, slope, and flows) and what is to come.  To be an ecological designer requires skill and it relies on a balance of pattern thinking and the materialistic (information based) perspective. Knowing how to create maps and designs

Treasure lake, KY, USA 20ft (6 m) contour lines

Treasure Lake, KY, USA GIS 20ft (6 m) contour lines

and then making them legible to explain the design is one of the vital skills permaculture designers must employ for the design based science.  We lost the need for design when fossil fuels became widely available along with synthetic and highly mechanical inputs (i.e. from pesticides to reticulated water).  This changed the face of how we interact with farm landscapes and even village design. However, when we apply permaculture design to such contexts and we utilize the patterns of nature in space and time, the principles of permaculture, we can create abundant results.  Maps allow us to better plan earthworks, tree crop systems, rotational grazing, and to layout housing development amongst others.  However they are maps only, not the territory itself, so planning on a map can only get you so far because the in the field feedback will always cause variations no matter the accuracy of the map.

Sourcing Map Materials

With that, the first question remains what resources can I utilize to develop a map for either our own sites or those we are working on for clients? Often it is a combination and if we invite the permaculture principle of diversity then we can see the need for a combination of resources.  The following are the most commonly used:

  • Satellite images like from Google Maps, BING maps, and…
  • GIS (Geographical Information Systems) websites from the state
  • Deeds, which have property line mapped out
  • Surveyor generated maps
  • Google Earth as supplemental tool but not generally a map making tool

I tend to use a combination of as many as possible when the availability is there.  It’s not easy making maps in some parts of the world while others its extremely easy.  For example at my families land in Kentucky, USA, I can utilize high quality maps from GIS systems to get started.  They give relatively precise boundaries and even better they offer two foot (60 cm) contour lines.  This allows for a greater depth of planning not possible when just using a Google maps screen shot.  However, with Google maps there they offer a lot more satellite images from year after year (or used to).  This allows me to effectively utilize the history button they have them to see the progress over the years of how the site has evolved.  However in Portugal neither are available, which has made documentation and planning of the small scale intensive project of Terra Alta more difficult.  The Google maps image is dated to say the least, around 2009, and there is no GIS (SIG in romance language) available.  BING however does have more up to date satellite imagery in general there in Europe. In Portugal when I have had access to contour maps they were all made with a surveyor, which allows for a greater depth of designing and planning due to contour map generation.  This has allowed for water and earthworks systems developments like Keyline, which is absolutely necessary to have good maps for the initial stages of design. There I have also developed base maps with the use of deeds because it is the only reference of property lines.  Google maps images provide this nice resource of a satellite image but no clear indication where a property ends, unlike GIS.  Thus combining the deed with this allows for a base map to be drawn up.  Often lines of trees on a boundary helps to bring the two together when doing an overlay.  I can reference a certain boundary I see on the map and fit the two to scale.

Scale is really important to capture when doing accurate design work.  Thus when I capture a Google maps image I always am sure to include the scale that is in the bottom corner.  In fact, no mater the source I always capture this.  This is one drawback from Google Earth, as well as its lack of a good straight down image, as there is no scale reader. You can get around that by simply drawing in a line and using the measure tool and then capture the length in the screen shot.  If going with Google earth it’s best to just use that as the medium of design rather than transporting that software into Powerpoint, Illustrator, or the like because of this lack of a straight down image.  Also with feedback from other designers, Google Earth’s altitude measure is often inaccurate.  It is one way to build a contour map by placing dots and connecting them but it will only give a rough outlook as opposed to a GIS or surveyed map.  Even those have their discrepancies so remember the old adage,”The map is not the territory“. The satellite maps also help to show where existing vegetation, access, and infrastructure is so you can put those into the base map by simply tracing over them.  It’s essential for our work. If you would like to see more on how to use Powerpoint as a design tool please consult this article I had published at PRI: How to Use PowerPoint as a Design Tool: By Doug Crouch. Building a base map with Powerpoint can also be seen at the very bottom of the article in a series of pictures.

The Keyline Pattern, a very effective and cost efficient broad acre technique of land regeneration

The Keyline Pattern, a very effective and cost efficient broad acre technique of land regeneration

Understanding Topography

Again, one of the most important tools that a map can provide for you is the look into topography given that they provide one with a reasonable level of accuracy. They show the curves of nature as water and weathering has sculpted the landscape. The numbers associated with the lines are how far above sea level that particular spot is within contour.  A line is drawn where other points are at this same altitude, which gives you a fairly accurate description of the relief (ups and downs so to speak) of a site.  If you only use spot elevations, just random numbers in random locations, then you can’t get an accurate picture of relief as you see with the graphics below.  Here you see both contour and spot elevations but by seeing the second picture, below right, with the contour lines you can see how steep the land is and how it changes more accurately.  The really steep wall seen on the left mountain in both the pictures below is called an escarpment but you really can’t tell from just the spot elevations.

Furthermore, the second map at the top left of the article, I show is of 20 foot (6m) spacing.  On a large piece of land like this one, 66 acre or 27 ha, it helps in getting to know the”lay of the land”. You can see the relationship between valleys and ridges and degrees of slope but to plan something like a swale, pond, keyline or a house site, you would want something with a closer contour line spacing.  Surveyor maps are often 50 cm or 20 inches apart or even down to 30 cm or 12 inches in some cases.  The GIS map at the top of the page shows two foot or 60 cm spacing of the same land.  This gives plenty of accuracy for planning such systems as you can really zoom in and see the subtle differences.

 

When looking at topography our brains need to extrapolate out the lay of the land to see in 3-dimensions.  They help us to see when landscapes are steep and when they are gentle.  You see ridges and valleys and you need to be able to see these conditions not in 2D, like the map, yet rather 3D from our minds pulling them outwards.

Thus when you go to read a map, when the lines are spaced close together, that means there is a rapid change in altitude indicating a greater percentage of slope.  This affects how water flows as the steeper the hillside the more likely we are to have erosion.  Also it changes our earthworks capabilities as you move up in steepness swales are not possible and then we need to go to terracing when such earthworks are really needed.  If contour lines are spaced really far apart when you have say an accuracy of two foot (60 cm) then the land is quite gentle and approaching flat.  Also when reading such maps it can take some time to see where there are valleys and where there are ridges and their relationship in terms of size in the landscape.  You can always find valleys through looking at the contour lines and seeing the way in which they point in terms of the contour lines changing in altitude.  If they point towards a higher number, say 520 feet above sea level pointing towards 540 feet, then you know it is a valley.  It’s the opposite with the ridge with it pointing down towards 500.  Take the test below and see if you can use this knowledge to match the numbers with the appropriate letters on the corresponding landscapes.  So the contour lines help you decide which landscape is which.

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Using maps to help with Planning/ Design Process

A map can again help with a diversity of tasks around planning; before, during, and with the implementation.  If done to scale one can figure out accurately just how many trees are going in, how long say a swale will be, catchment size, or where a house would fit perfectly in with all the other stuff going on already. Thus once a base map is created, analysis tools like sectors and flows are done.  Our sector and flow analysis helps us to put in a windbreak or know when an earthwork like a rain garden should be placed. Then the schematic part comes out and dictates where a bubble like food forest will go.  Then you refine that idea more and do a detail design and determine exactly the numbers of trees and when and where they will go (design process).  Again when reading a map and seeing the steepness of the land and the valley to ridge relationship, we can appropriately choose and place earthworks. So you are constantly going back to the maps and referencing the topography maps for this as the design process evolves. Below the maps are brought together from GIS sources and put into powerpoint to examine the site. It shows the process of how I came up with the swale placement on the land.  Its size was roughly planned here but also in combination with other planning tools like rough catchment calculations to determine the volume needed for the earthwork.  I say this to demonstrate that maps are just one of the tools we use in our toolbox to generate a design, but they are indeed vital for our success in communicating space and time relationships, how energy circulates through a site, and inspiring the dream of what could be.

Written by Doug Crouch

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