GPS, or Global Position Systems, is a satellite navigation system that provides the ability to determine locations anywhere on the earth. The system completed by the U.S. Government in 1994 is a constellation of about 24 satellites which emit coded signals that allow the user to very accurately determine their location on the Earth.  To get this information requires a user to have a GPS receiver.

Most GPS receivers have the ability to record locational data in the form of points (example, location of a building), a line (example, a trail) or an area (example, a lake). This can then be converted to a file that can be directly imported into your GIS system.

This can be extremely useful for land trusts - any work you do in the field can be accurately mapped and uploaded directly into your GIS. This applies most directly to the stewardship/easement monitoring activities, but has other applications as well, here are some examples:

• Baseline Mapping - When a new conservation easement is established, GPS can be used to collect information about that property and help to create detailed maps as part of the baseline report.
• Photo Points - GPS points can be taken at photo points in the field and then the photos can be uploaded as a point layer into the GIS database. Information about the photo - location, direction of photo, subject of photo, person taking the photo etc. can be added to the table associated with the point.
  
• Field Surveys, Natural - A wide variety of natural features on the ground can be mapped using GPS while out in the field including invasive species, soil erosion, fire disturbed areas, trees or plants of special concern, lakes, riparian areas, and streams.
• Field Surveys, Man-Made - A wide variety of man-made features on the ground can be mapped using GPS while out in the field including buildings and other structures, roads, driveways, trails, fences, powerlines, levees, etc.
• Locating features in the field - It is also possible to upload GIS data onto your GPS unit and navigate to those locations while in the field. For example, if during the baseline mapping a patch of invasive plants was recorded, you could upload that information and relocate the area in subsequent years.
  

What It Takes

GPS can be integrated into a Land Trust on a number of different levels. What used to require a GPS receiver now can be accomplished using a standard smart phone.  GPS has really expanded into the realm of everyday data users.  Depending on the GPS enabled device being used it may require some skill and some software knowledge to get the data from your GPS device to your GIS system.

Basic - The most recent and simplest device is the smart phone with GPS enabled.  The quickest technique for projects requiring dedicated GPS is to go to your local outdoor outfitter and pick up a receiver. These can run in the range of $250-$1,000. There may be options for less, but you will want the ability to record data and these units start at around $250. Garmin and Magellan are industry standards for low end units.

Garmin units are preferable because of the free software utility available for converting data from your unit to a GIS created by the Minnesota Department of Natural Resources.  This extension will allow you download your collected GPS data into your GIS or upload existing GIS data into your GPS. It works with most Garmin units.

The main limitation to the Basic option is that the receiver has a small, usually black and white screen which allows for sub-par navigation and limits viewing a digital map on your GPS screen while in the field. These units are also limited in collecting attribute information about features you define ("waypoints"), other than a short name and ID number.  If you want more information about the feature you need to right it down on datasheet or in a notebook with the corresponding waypoint number and then manually enter into your GIS once in the office.

Intermediate - The next step up allows for enhanced data collection, map viewing in the field, and navigation. Using a Personal Digital Assistant (PDA - for example, the HP IPAQ) and a plug-in GPS receiver (fits in a PDA expansion slot),  you can gather more extensive attribute information. Combined with a program like ESRI's ArcPad, this system functions as a robust GIS allowing you to have immediate access to your field data for GIS use. This whole package will cost about $1,000- $1,500 per unit but is considerably more useful than the basic option.

Once it is all set up you can upload aerial or satellite imagery onto your PDA with any other vector data and bring it out in the field with your. If you are going to visit a property to collect some information on the trails on site you will have the ability to see an aerial image of landscape as you are walking along the trail collecting information on the width of the trail, erosion problems, or other characteristics.

Advanced -  If your land trust is collecting large amounts of complex data and very high accuracy is a priority you will need a more sophisticated solution.  At this level you will have one GPS unit that does everything the PDA option offers except it is already integrating into one unit. Trimble, Magellan and Leica are the industry leaders and offer a wide suite of different units that range from $2,500 - $15,000. These units come fully loaded with their own proprietary internal software for complex data collection and integration with GIS, a good sized screen for viewing GIS data on your unit while in the field, alpha-numeric keypads for easily typing in information about features, and post-processing software for producing locationally highly accurate data. They may also be available for rent from providers in your area.

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MORE INFORMATION

Wikipedia GPS entry

- General web site for all types of GPS information and products

- Garmin information on GPS