What Is GIS?
The term GIS involves powerful, complex computer databases that organize information around a specific location. A simple description used by the Crescent School in Toronto, Ontario, Canada is "a computerized map with a potentially unlimited amount of information available for every point on that map."
Paper maps have always displayed various kinds of information. State highway maps, for example, show not only highways but also include the locations of cities, lakes, rivers, parks, and state and county boundaries.
Each category of information is called a “theme” or “layer.” The information on highways is one “theme” or “layer;” the information on county boundaries is another. One advantage of GIS over paper maps is that many more layers can be displayed in various combinations.
An Analytical Tool
The real strength of GIS lies in its potential to assist people in analyzing data and making informed decisions. Stacking themes or layers of information allows new patterns to emerge for scientific consideration. When information concerning different resources—such as wildlife, minerals, plant, hydrology, and soils—is entered into GIS, managers can look across disciplines and see the “big picture.” For example, newly discovered archaeological sites or endangered-species habitats can be seen along with standard hydrology and vegetation maps. GIS technology is used by resource managers for a number of purposes such as determining suitability of an area for wildlife habitat, mapping areas at risk for fire, or assessing the health of rangelands and riparian areas in order to manage grazing practices.
Another advantage to GIS is its ability to show changes in information over time. Data can be collected from even antiquated sources. In Wisconsin, some surveyor’s plats and field books are so complete that the state’s vegetation layer goes back to the 1850s. Trends can be projected into the future as well. In Southern California, support for managing development in San Diego and Los Angeles to protect rare desert species was boosted when the public was able to see, through GIS modeling, projected results of development trends over time. This resulted in the protection of more than 81,000 hectares of desert habitat.
All information that goes into GIS is tied to a point or location on the surface of the Earth. There are two primary coordinate systems used to describe location: spherical and Cartesian. Spherical coordinates are also known as latitude and longitude. Used primarily for navigation, these are measures of angular distances from the center of the Earth, north to south and east to west. This system is not suited for measuring precise distance and area on the land, however. Better for this is one of the Cartesian coordinate systems, which are based on map projections. These mathematical projections allow the curved surface of the Earth to be portrayed on a flat plane. (Try peeling an orange in one piece and laying the rind flat. The fewer cracks and spaces you have, the better the projection. Try peeling several oranges to see which one works best.)
Although there are many map projections, the one most commonly used in map making and in natural resources data collection is the Transverse Mercator Projection because it minimizes distortions caused by flattening a curved surface. The coordinate system based on this projection is called the Universal Transverse Mercator (UTM) Grid, which measures in meters the distance from an origin point on the equator. It is important when entering data into GIS that information on the coordinate system used to collect the data is provided to the user. That way, all data can be converted to and used in a single system.
The Public Land Survey System
Land ownership records are tied to another system—the public land survey system. Land surveys describe parcels of land and are the foundation of our system of land tenure (the record of who owns what and where it is located).
There are two very different types of land surveys conducted in the United States: (1) “metes and bounds” and (2) “grid” or “rectangular” surveys. “Metes and bounds” surveys trace boundaries based on physical features of the land, such as trees, boulders, roads, and fences. These were used in surveys of the original 13 colonies.
In a grid or rectangular survey, the land is described in relation to the “township” and “range” system established by the Land Ordinance of 1785, a law to encourage settlement of the lands west of the original 13 states. The resulting rectangles, known as “townships, sections, lots, and parcels,” are tied to a “meridian” or a “base line.” Meridians (which run north and south) and base lines (which run east and west) are long, straight lines used as reference points for the small rectangles established by the surveys. Today, the metes and bounds survey system is used in the 18 eastern states, plus Texas and Hawaii. The “rectangular” system is used in the other 30 states, and is most evident west of the Mississippi River. Together, these two survey systems provide the basis of our system of land ownership. There is currently an effort underway to tie the public land survey system to latitude and longitude, so this information can be easily used in GIS.
Collecting Data for GIS
There are many uses for GIS technology in natural resources management. But with all the sophisticated technology, the simple fact remains that GIS maps are only as good or accurate as the data that go into them. Significant amounts of data have been collected in the past 25 years, and much of it is widely available.
Data exist in many forms, depending on the intended use of the information. Data can come from old-fashioned maps, survey plats and field notes, or from state-of-the art Global Positioning Systems (GPS) and remote sensing. Examples of remote sensing include but are not limited to infrared photography, photogrammetry (using photographs to measure and map an area), aerial photography, or satellite imagery. The federal government, commercial, international, and other sources digitized maps. Natural resource and other data can then be layered on top of these data sets. Sensors such as cameras, rain gauges, wind gauges, or thermometers can be employed to record data at a particular location. Some of these sensors are automated and continually send in new information. More often, however, natural resource specialists gather data in the field. The accuracy of GIS data layers depends on careful field checking and verification of this new data.
For example, the Bureau of Land Management’s (BLM) Eagle Lake Field Office in northern California created a base vegetation map of all the public lands in the Susanville area, covering more than 1.2 million hectares. To create this map, a satellite image was made of a 161-square-kilometer area, called a “scene.” A remote sensing specialist analyzed this “scene” and classified the information according to vegetation community type (such as grasses, shrubs, and forbs). A botanist then verified the accuracy of this work through field observations. This verification process (also known as “ground-truthing”) is essential with high altitude imaging in order to make sure that what is on the computer screen is an accurate representation of what is on the ground. Once the information and field observations have been converted into data and digitized, they will become a layer or theme for use in GIS maps. Other important layers are USGS terrain data, land ownership data, or state and county maps showing major roads, rivers, and cities.
An Innovative Approach
Satellites, planes, and helicopters can be used to collect data from the air. But to get an even closer view, an innovative group of scientists used a small remote controlled airplane to document the BLM’s Red Gulch Dinosaur Tracksite in the Bighorn Basin of northern Wyoming. This 16-hectare site contains hundreds of fossilized dinosaur footprints. Part of the tracksite, nicknamed "the ballroom" for its series of dinosaur steps, is important in that it could reveal social habits of dinosaurs during the Middle Jurassic Period, 165 million years ago.
In order to photograph this unique site, scientists mounted a 35 mm camera on a low altitude remote controlled airplane and were able to take a series of aerial photos while flying 43 meters above the ground. The pictures were then pasted together to create a panoramic, high-resolution mosaic of the ballroom. These photos are being included in a database with other information collected by a team of scientists. Examples include detailed measurements of the individual footprints, survey coordinate data, geologic information, large-scale aerial photographs, and close-range stereo photographs. This data will be integrated into a GIS framework so that all site documentation will be tied to a picture or "map" of the site. This provides the detail needed to analyze the tracks and trackways in order to draw conclusions about the activity patterns of the dinosaurs that made these footprints.
Scientists also took close-range stereo photographs of the tracks in order to study the shape of the footprints in great detail. These photographs were used to make three- dimensional or elevation models that represent the track-bearing surface and will be used to compare different footprints within the Red Gulch Dinosaur Tracksite as well as with tracks from other locations in the world.
Global Positioning System
For collecting data on the ground, Global Positioning System (GPS) receivers are commonplace. GPS is a satellite navigation system developed by the Department of Defense that can pinpoint a location anywhere on Earth. GPS receivers are able to obtain signals from satellites orbiting the Earth. Signals from three of the 24 orbiting satellites are needed to calculate latitude and longitude, using basic triangulation methods. A fourth satellite signal can be used to calculate altitude. Because the Defense Department obscures exact readings for security reasons, GPS readings are not 100 percent accurate for civilian use. GPS can locate positions within 100 meters of a point, however, and taking several readings over a number of minutes can improve the accuracy to 50 to 20 meters. Using two GPS receivers, with one on a known location, can also increase accuracy.
GPS offers a range of possibilities for users, limited only by the imagination. Units are used in rental cars, delivery trucks, on recreational boats, and in backpacks. Applications in natural resources management are just as varied and include mapping natural and cultural resources, navigating in remote areas, and monitoring wildlife migrations.
Sharing GIS data can be challenging and is complicated by incompatible GIS systems and incompatible data used by federal, state, and local agencies; universities; and private industry. While the GIS industry is working hard to develop software to make separate systems “talk to each other,” resource specialists are still struggling with standards for data to go into these systems. How data are put into the system determines the accuracy of the system and the scale at which one can work with it.
Developing data standards is not a simple process, however. It is difficult to reach agreement on what the standards should be because users’ needs vary. In terms of scale alone there is wide discrepancy. A point on a national map representing a section (259 hectares) could be adequate detail for a map showing weed infestations nationwide. But at a county level, a manager could not find the weed infestation in 259 hectares without more information on its location. In addition, some databases record plants by genus, while others use species only, and still others use one of a number of code names. These are just a few of the myriad issues related to data sharing.
At the national level, the Federal Geographic Data Committee is working to establish data standards, coordinate data collection, and establish a common infrastructure to enable sharing of information between agencies. The committee represents 16 agencies but is reaching out to state, local, and tribal governments; private industry; and universities as partners.
GIS in Action
As GIS technologies become more accessible, land managers increasingly use GIS to make decisions and communicate with the public. GIS allows people to see data at both large and small scales. Among large-scale GIS projects underway in federal resource management is the USGS National Biological Service’s “Gap Analysis,” an effort to look at where the major gaps exist in the distribution of wildlife and plant habitat and the management of these across the nation. GIS also figures prominently in developing comprehensive management plans over broad areas, such as in the newly designated Grand Staircase-Escalante National Monument in southern Utah, encompassing 769,000 hectares. But many GIS applications are smaller in scope.
One such project involved finding the flat tailed horned lizard in the Arizona Desert. These small creatures can be hard to locate, especially during the day when they take cover from the heat. In 1993, the U.S. Fish and Wildlife Service proposed the flat tailed horned lizard as a threatened species. Land managers wanted to know where they might find the lizards throughout remote areas of the Barry Goldwater Air Force Range near Yuma, Arizona, in order to more accurately protect and manage them. Rather than walking the entire area, biologists took a more systematic approach. First, they documented several field observations of lizard tracks and scat. The associated vegetation and soil properties in these areas became indicators or “signatures” of potential lizard habitat. This information was correlated to satellite images from the Landsat Thematic Mapper sensor. GIS specialists used these “signatures” to locate other areas that had high probability of containing lizards. Field checking verified that this method worked well to predict areas of high- to moderate-density lizard populations. Maps of these areas were then provided to field biologists, enabling them to concentrate their work in areas likely to contain lizards.
GIS Battles Weeds
GIS technology also helps land managers fight the battle against invasive exotic plants that are spreading across the country at alarming rates (1,862 hectares a day on federal lands alone). In Wyoming’s Bighorn Basin, where weeds are invading large areas of critical high desert habitat, the BLM is spearheading an extensive weed inventory that has already entered data for more than 400,000 hectares into GIS format. Field personnel used GPS units and old fashioned field mapping (by USGS topographic quads) to document weed locations. So far, more than 3,000 locations have been found, verified, and recorded. Maps are easily updated as new weed locations are found, and are used to pinpoint areas for treatment. Consequently, weed specialists have been able to keep some infestations of spotted knapweed under control. This long-term proposition requires constant vigilance. Some weed seeds stay viable in the soil for 15 to 20 years, and new species are always cropping up.
In addition to providing the basis for treatment plans, GIS maps can be a powerful education tool. By sharing up-to-date data with neighboring land owners, land managers are seeing increased interest in battling the spread of weeds. The GIS technology allows land managers to illustrate—in a picture—the hypothetical or potential exponential growth of weed infestations over time. Indeed, these pictures do speak thousands of words.
In Miles City, Montana, resource specialists from the BLM, county weed supervisors, and a number of national and local partners, including students from Forsyth High School, conducted an extensive inventory of 690,000 hectares to document the location of weeds, particularly leafy spurge. Traditional on-the-ground inventory methods are cost prohibitive over large areas. Using helicopters, however, scientists and students were able to cover thousands of hectares a day to mark locations of weed infestations with GPS. This data was downloaded into GIS software, enabling the students and recent graduates to create detailed maps showing the infestations. Within 10 days, the team gave neighboring landowners up-to-date maps of weed infestations in their own backyards. With this information, landowners agreed to treat these weed infestations. This level of early detection and rapid response would not be possible without GIS technology.
Firefighting with Technology
GIS maps help land managers identify areas at risk, not only from weed invasions but from wildfires as well. The National Interagency Fire Center in Boise, Idaho, uses remote sensing satellite imagery and GIS to map fire fuel loads and to locate fires quickly. Fuel load modeling, when analyzed with weather patterns, can help predict fire danger. A wet spring can increase fuel loads, which are determined by calculating the kilograms various vegetation types, and the fire’s activity inside and outside the perimeter. Thermal infrared scanners mounted on aircraft can pinpoint a 15 cm hot spot from an altitude of 2,400 m above the ground. Information from the scanners is then transferred to topographic maps, giving managers precise location information.
Federal fire dispatchers in Utah plot fire locations on a GIS map to assist them in making quick, accurate decisions about fire suppression. The map can display more than 20 themes or layers of information allowing managers to consider such things as vegetation types, proximity to structures, rights-of-way, archaeological sites, rivers and wetlands, threatened or endangered species, and sensitive plants to determine the best approach. They also can look at fuel loads, weather patterns, and past fire history to assist in predicting likely fire behavior. Utah State University (USU) graduate students helped develop this system as part of USU’s Landscape Ecology Model Analysis (LEMA) Center, a cooperative BLM program with USU.
Multi-level analysis: The Northwest Forest Plan
One of the most comprehensive natural resource projects involving GIS was undertaken as part of the President’s Northwest Forest Plan of 1993. This plan outlines a comprehensive program to manage close to 10 million hectares of federal forest lands across western Oregon, western Washington, and northern California. Beginning with the controversy over protection of the northern spotted owl, the plan ultimately adopted a broad goal to protect the diversity and health of entire ecosystems while providing for a sustainable level of timber harvests across the vast landscape.
Under the plan, activities such as timber sale planning hinge on careful watershed analysis. Watershed analysis organizes data at a watershed scale and provides a basis for land managers to look at the big picture in making decisions.
Historically, decisions were made on a site-specific scale through individual “project plans” with little consideration of the impacts on neighboring areas. Under this new approach, more information is analyzed on a larger scale as managers consider not only a single action’s effect on their lands but also all agency actions and their collective effects on the entire watershed. Experts suggest this requires a level of analysis only possible with GIS technology. To provide the information needed to perform such analysis, more than 50 GIS experts from three federal agencies created a regional GIS database containing more than a hundred layers of information, with more added as new information becomes available.
At a local level, this database allows managers to perform the complex analyses required by the plan and to meet the objectives of a comprehensive watershed conservation strategy. Information on the age classes of tree stands; locations of spotted owl reserves; definition of riparian areas, streams, and associated buffer areas; and habitat of lesser known species are just a few of the themes of local and regional maps available to land managers on desktop computers. This information allows scientists to create models that will show effects of different actions over time, illustrate long-term trends, and predict future conditions. To many, GIS technology alone has made possible the change in the way natural resource decisions are made in the Northwest. through the use of GIS. (Photo of the NW forest).
School Uses GIS to Assist Watershed Analysis
A key feature of The Northwest Forest Plan is that it encourages communities to get involved with local ecosystem management efforts. Students at Glide Middle School have taken on this challenge by collecting and recording data on water quality in the Little River Adaptive Management Area adjacent to the small community of Glide, Oregon. This is a unique ecosystem designated in the Plan to encourage managers to try new approaches to manage timber harvesting while restoring and maintaining sensitive riparian areas. Some of the streams in this watershed are listed as water quality impaired by the Oregon State Department of Environmental Quality; careful monitoring of water quality over time, therefore, is important.
Each fall, agency hydrologists and GIS specialists train a team of six student leaders in GIS techniques and the use of a water quality instrument for measuring stream pH, conductivity, turbidity, stream temperature, and other water quality elements. Throughout the school year, teams of students measure water quality at five locations within the Little River watershed on a weekly basis. Students transfer the data to GIS Arcview software; students can then see how water quality relates to other components of the watershed's ecosystems and to ecosystem management practices. The students also e-mail their measurements to the GLOBE (Global Learning and Observations to Benefit the Environment) program, a worldwide network of students, teachers, and research scientists who monitor the worldwide environment and share observations via the Internet.
Elementary Students Develop Road Proposal
Increasingly, GIS is being introduced at the upper elementary level. Fourth- through sixth-grade students at Joseph Cook Elementary School in Utah used GIS to analyze state plans to build a road in the Salt Lake City area in order to reduce traffic congestion. One plan called for a road that would run through Antelope Island, a prime recreation area. Students found that existing maps of the area contained conflicting information. They took a field trip to the recreation area to compare the maps with the site, then returned to the site with GPS units to measure key features.
Back in the classroom, they produced updated GIS maps, analyzed the proposed route, and developed a preferred alternative route for the road. They shared their data with the state’s Automated Geographic Reference Center and were most pleased when they compared their preferred route with that of the Utah Transportation Authority—they matched! The students’ teacher credits the GIS exercise with teaching them how to think spatially and integrating subject areas such as geography, math, and language arts. But most impressive is that the fourth-, fifth-, and sixth-grade students met challenges and complexities normally expected of individuals twice their age.
Government and Businesses Assist Schools with GIS
There are many government agencies and private corporations reaching out to assist schools in using GIS on their own campuses. One such example is at Piney Woods School outside of Jackson, Mississippi. Here, through private and federal grants and ongoing assistance from the Bureau of Land Management, officials have trained students to conduct extensive urban tree inventories using GPS and GIS technologies on the school’s 81 hectare wooded campus. A fully-operational GIS laboratory at the school is used by all urban forestry, biology, and chemistry classes. Training includes a three-day teacher workshop on Arcview, a popular GIS software, and student instruction in GPS and tree species identification. Students then receive instruction on how to collect data and use the Piney Woods Tree Inventory System to complete an Urban Ecological Analysis. The urban forestry class meets once a week, alternating sessions between field data collection and computer laboratory data entry. By plotting trees on a map of their campus and then recording information such as tree location, size, and species, students can calculate air pollution removal rates, energy conservation, carbon storage, and sequestration rates for their urban forest. In the process, students learn the value of trees in urban environments, such as reducing air pollution, conserving energy by providing shade to buildings and air conditioning units, reducing erosion, and providing aesthetic improvements. For more information on this program, go to http://www.pineywoods.org, then click on Facilities.
FOR THE CLASSROOM
Locating a Campground Site and Mapping Exercises
Click Here for additional mapping exercises including one where students take on the role of land manager and designate a campground in the remote Grand Staircase-Escalante National Monument.
What Data Do You Need?
This exercise demonstrates how having the right data and the ability to view them simultaneously allows for better decision making.
Tell the students that they are going to act as city planners. Talk about what a city planner does. You may want to invite a city planner into the class to talk about his or her job.
Read the following scenario to the students: The citizens want to install a swimming pool in their city park. (Ask students to identify city or other parks that they have visited. How might the parks be improved? Did the park have a swimming pool? What other facilities did it have?) To locate the best site for the swimming pool, certain information will be needed. Explain to students that as a city planners, it is their job to identify the kinds of information that are needed. Make a list of the ideas the students come up with. Examples might include: boundaries of the park; locations of existing facilities, such as sidewalks, playgrounds, gardens, parking lots, and restrooms; corridors for utilities, such as buried or overhead electric lines, water lines, telephone lines, and other cable; traffic patterns both outside and in the park; shade trees; and wildlife habitat.
Explain that the information linked to a physical location can be displayed on a GIS, and several themes can be simultaneously displayed. Ask students why this is important. (This allows the decision maker to see several different factors all at once.) Have students give some examples of information they will need to know about the area. (For example, the pool could be located in an area that is easily accessible for people and where wildlife habitat is not affected. Wildlife habitat, water lines, and road maps would be useful here.)
How Much is Too Much?
Although GIS can display a limitless amount of information, displaying multiple layers of data at once can make a map indecipherable. Most uses require that only a few data layers be analyzed. A major benefit of GIS is that it can depict only the data that are needed. To demonstrate this to students, either hand out a photocopy of a section of a state road map (choose a section that already has a lot of information displayed) or project the image with an overhead projector and have students work along with you.
First discuss what information is already shown on the map. Ask students to think of other hypothetical data layers (such as farmland and non-farmland, clay soils and sandy soils, landscapes visible and not visible from a road, and high income and low income areas.) You will now add symbols and/or large areas of overlapping color to the map, showing the locations of these data themes. Place press-on stars or stickers to indicate bird nests, rest areas, and springs. Draw lines to show powerlines and railroads.
This exercise quickly demonstrates that it is as difficult to plan a project with too much irrelevant information as it is with not enough data. Emphasize to students that a GIS can display only the relevant data, and that the data sets required may vary according to the project.
Create a Grid System
The various mapping grid systems described in this article provide a critical element for using geographical data: they are reference points from which all other locations can be described and relocated. This system allows the transfer of information to anyone else who can “read” the grids. In this activity, students create their own grid system to describe a location. Give each pair of students two oranges (a ping pong ball will also work for the first part of this exercise) and two markers. One student draws a star, a triangle, and a dot anywhere they want to on the “globe” without letting the other student see. The student with the blank orange now tries to duplicate the markings on his “globe,” following directions from the first student, who is not allowed to use measurement terms. The students will quickly see how difficult it is to complete the exercise.
Working in pairs, students next invent a system that will allow them to reference their markings and accurately describe the markings’ locations to their partner. Most students will create a variation of a grid system on the “globe,” and some may invent a system that references to a datum that is not on the globe. This would be equivalent to a GPS satellite.
If the students use an orange for the exercise, have them attempt to peel the orange so that the skin remains in one piece. Laying the orange skin flat will cause it to split from the top and bottom. This demonstrates the concept of the Mercator map projection.
Mapping Central City, Colorado
This is a more indepth activity illustrating the use of maps and aerial photos in answering natural resource questions. Students also draw their own map from a grid they create, transferring natural resource features onto the grid from the photo and topographic map. The exercise, suitable for upper elementary school students, is posted on the BLM’s Web site at http://www-a.blm.gov/gis/narsc/national.html. Click on nstamapmaking.html.
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About the Authors
Melinda Walker is a remote sensing specialist at the BLM’s National Applied Resources Sciences Center in Denver, Colorado. Julie Casper is a remote sensing specialist with the BLM’s Utah State Office in Salt Lake City, Utah. Frank Hissong is an outreach specialist with the Geographic Sciences Group in BLM’s Washington, DC office. Elizabeth Rieben coordinates national environmental education programs for the BLM in Washington, DC.
The authors would like to acknowledge the following BLM employees for their contributions: Jerry Asher, Dayne Barron, Bibi Booth, Todd Christensen, Stephen Christy, Dan Couch, Duane Dippon, Peter Dorn, Pat Durland, Shelly Fischman, Gary Gale, Tom Gough, Lars Johnson, Hubert Livingston, Neffra Matthews, Dianne Nelson, Jeff Nighbert, Dianne Osborne, Peter O’Tool, Jim Rolfes, Bob Schoolar, Shelley Smith, Woody Smith, and Sheldon Wimmer. The authors also would like to acknowledge Brent Breithaupt, Director of the Geologic Museum, University of Wyoming; Danielle Bruno, Idaho State Department of Agriculture; Don Cressall , Electronic Instruction Specialist for Davis School District in Utah; Richard Rieben, GIS Specialist, Winstar; Barbara Ward, Piney Woods School; and Theresa Foster, GIS Specialist, St. Paul, Minnesota.
Environmental Systems Research Institute, Inc. (1998). Explore Your World with a Geographical Information System: A Teaching Supplement for Grades 5–12. Redlands, CA: Environmental Systems Research Institute, Inc.
Friedrich, R. L. and Blystone, R. (1998). Internet teaching resources for remote sensing and GIS. BioScience, 48(3) 187–193.
National Geographic. (1998). Geography Awareness Week 1998: Exploring People, Places and Patterns with Geographic Information Systems. (CD-ROM). Washington, DC: National Geographic.
Robison, L. (1996). Plotting an island’s future. Geo Info Systems, 6(5), 22–27.
U.S. Geological Survey, U.S. Department of the Interior. (1998). Geographic Information Systems. (Brochure). For a copy, call 1-800-USA-MAPS or visit http://www.usgs.gov/education.
Environmental Systems Research Institute
Mapping the National Parks, Library of Congress: 200 maps dating from the 17th century at l
National Geographic Society
National Interagency Fire Center:What Data Do You Need?
National Public Radio (Interview on the Fire Center and infrared mapping.)