Wednesday, January 25, 2006

Maps

Two posts in one day! Pent up information to share, I guess....

In order to live successfully within the means and renewable resources of your home area, one needs to be familiar, I would suggest, with the "lay of the land." This means both locally, in the distance you might likely walk in a day to the market, etc., and in the larger area, your bioregion or ecoregion, that your local area is a part.

That means having maps at your disposal, and being familiar with what's on them.

I won't be teaching you today how to read a map, but will start by pointing you to resources and places to get maps.

In the U.S., the government agency most responsible for maintaining maps for the entire country is the Geological Survey (aka USGS), which is part of our Department of the Interior. (Other countries have their equivalent agencies, such as the Ordnance Survey in the U.K.) Other agencies will also be involved, including, but not limited to, state Department of Natural Resource offices, the Natural Resources Conservation Service (NRCS, formerly the Soil Survey), the National Biological Service (part of USGS), the Bureau of Land Management, the National Park Service, the Army Corps of Engineers, and so on. The USGS publishes the most general of maps (generally known as topographic maps), with the other agencies publishing more narrowly focused maps (e.g., soil surveys, Federal land ownership, navigation, etc.)

Topographic maps (the type I would suggest you want) come in a variety of scales. The most useful for our needs are 1:24,000 and 1:100,000 series of maps. "1:24,000" means that one inch on the map is equivalent to 24,000 inches on the ground, or about 3 inches on the map for each mile on the ground. These are the most detailed of maps published by the USGS for most of the country. Each map, about 2 by 3 feet in size, therefore covers about 6 by 8 miles of territory on the ground. Topography (land elevation contours), water features, roads, even individual buidlings, are given at this scale. The other useful scale, 1:100,000 has 1 centimeter on the map portray the distance of 1 kilometer on the ground. Individual building won't necessarily be shown any more, or elevation change at an interval more detailed than 10 meter of height change, but the trade-off is that these maps, covering an area about 30 miles across, permit you to see the bigger picture - your watershed in particular.

You can buy maps from the USGS directly or through designated map stores and outdoor specialty stores.

You can also get a number them in digital format through one or more government agencies (such as regional science centers of the USGS) that may make them available. To be most, you need to have GIS (geographic information system) software on your computer that know how to read the embedded coordinate information (in UTM coordinates) embedded in the digital image of the scanned map. (For instance, use the ArcExplorer software available for free from ESRI, one of the largest commercial GIS software/data providers, http://www.esri.com/.)

USGS maps are the basis for several online map servers, namely Microsoft's TerraServer site and Google Maps. Try these out:
Terra Server, http://terraserver.microsoft.com/

Google Maps, http://maps.google.com/

What is nice about both these sites is that they also include satellite imagery and aerial photography along with the maps. So as long as these resources are available, they are good to use.

But in the long run, I prefer the printed map. Paper maps are portable, can withstand wind and rain, don't require electricity, can be written on, etc. In the end they are more appropriate for a post-oil world, where electricity, computers, and the Internet may not be available.

Besides buy individual map sheets from your appropriate government agency, at least in the U.S. I'd suggest that you also check out DeLorme, in particular the Atlas & Gazateer series for the 50 states. Here is a link: http://www.delorme.com/atlasgaz/

DeLorme has taken the USGS 1:100,000 map data, resized it to 1:150,000 (slightly smaller, but still very usable), added stuff, and packaged it into atlases, one (or more if needed) for each state. Here in my area, Iowa, Illinois, Minnesota, and Wisconsin are each one volume. A bit pricey if you have to buy more than one state (I live on the edge of three states), but at $15 to $30 each (depending on state), they are still a good bargain. The detail is amazing, even at this smaller scale.

Other maps of use to consider getting are copies of the county plat maps. At least in the Midwest part of the U.S., where the Public Land Survey Survey was the basis for land subdivision, the counties each publish plat books and plat maps. While more of a schematic than a to-scale map, plat maps are useful in rural areas, showing individual properties, including detailed addresses (e.g., fire numbers). My wife keeps a set of these in her car for the two counties that her church parishoners (she is a pastor) live in. In needing to locate someone, they are very helpful. The plat book, very similar, but packaged in a book format (often by an independent publisher authorized by the county or township government), and has the added bonus of showing property lines and who owns it. Again this could be useful information if you are trying to organize your "rural neighborhood" into a community to help survive/thrive in post-oil times.

And yet another good resource to have might be your county's soil survey. Every state in the U.S. has a NRCS state office, and most counties (or groups of counties) will have an NRCS local office. Soil surveys, printed for most counties in the U.S. on a county-by-county basis, will provide good information on the soils on your particular property, and how they relate to the broader association of soils in your area. This in turn will tell you information about the bedrock in the area, the general fertility of the soil, and its water holding capacity and infiltration rates. While much of this will be interpreted on the basis (or for the use in) modern farming techniques, agribusiness, and petrochemical-based agriculture, the information is nonetheless useful. Again, they can be used to gain knowledge about the variability of soils in your bioregion. Check with the state office (or the soil science department at your state university) to see if other soil studies and maps have been produced. In some cases, digital versions of the soil survey (also suitable for use in GIS software such as ArcExplorer) may be available.

Enough for now....

Kevin Anderson

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