Environmental GIS: The World in a Computer - ACS Publications

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FEATURE

Environmental GIS: The World in a Computer Expanding data resources are spurring widespread use of geographic information systems in the environmental field. TONY R E I C H H A R D T

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eographic information system (GIS) computer programs that manipulate and analyze spatial data represent one of the hottest growth areas in the world of computing. Depending on what is included in the category "GIS software," the market is now worth between $550 million and $1 billion, and is growing at 15-24% every year. The number of software packages available for GIS analysis (2) is increasing, too, both at the high and low ends of capability. Much of this growth has been fueled by business applications, as companies recognize that GIS, with its ability to locate and sort potential customers, is a powerful marketing tool. But the environmental field continues to make up a large part of the GIS market as well. Environmental applications of GIS include site assessment and cleanup, wildlife management, pollution monitoring, risk analysis, vegetation mapping, and public information. Many natural resource managers now use or are familiar with GIS, and undergraduates in natural resource fields are likely to gain some experience with the technology before they graduate.

Such maps were available before computers, of course, but GIS technology makes them simpler and faster to produce. "It allows you to put information together from different sources that you would probably not ever have a reason to put together, and make sense of it easily," says Lehnertz. As the capabilities of GIS have improved and the number of applications grown, the definition has broadened. At a conference on GIS and environmental modeling held in January 1996 and sponsored by the National Center for Geographic Information and Analysis (NCGIA) at the University of California at Santa Barbara, center director Michael Goodchild said GIS has come to mean "the wide range of activities within the broad rubric of digital geographic information," rather than its original, narrower definition of "a software system designed to store, retrieve, and analyze existing geographic information." Whatever the definition, GISs share the ability to integrate and manipulate spatial data that have been "geocoded," or fixed in geographic space. These might include census data, ZIP codes, or digital photographs. Environmental researchers might use data on watershed boundaries, pesticide loadingfigures,EPA air quality readings, or locations of chemical factories. A GIS program typically deals with these various attributes in "layers," mixing and matching the information to reveal associations, for example, the relationship between household income and proximity to a toxic release site.

"The power of GIS is that it gives you the spatial component of information," says Mark Lehnertz, cofounder of Environmental Database, Inc., in Littleton, Colo. "Most people do not have the ability to carry an entire map in their head, and GIS gives you the ability to organize the information in a realworld manner." Lehnertz's firm produces customized GIS products, primarily maps, for environmental engineers and consultants, law firms, chemical companies, and others. Most of the data used in these GIS analyses are publicly available; for example, information on leaking underground storage tanks might come from a state environmental agency; hydrological data would come from the U.S. Geological Survey (USGS), and soil maps from county or federal agricultural agencies. With little effort, a GIS can combine all these data to map likely sites of groundwater contamination.

Growing data resources available One key reason for the mushrooming popularity of GIS has been the increase in availability of different kinds of geographic data in electronic formats. Purvi Rajani, market research director for GIS World, Inc., publisher of the industry's leading trade magazine, says that "traditionally in this market, people had to create their own spatial databases, whether it was digitizing maps or scanning aerial photos. But what we're seeing is increasing availability of already made databases."

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Lehnertz agrees that "information is becoming cheap," as the federal government continues to digitize its vast holdings of natural resource data. As it does, environmental scientists, engineers, and lawyers are among those making greater use of it. Coordinating the push to make more government data available in digital form has been the Federal Geographic Data Committee (FGDC) created by the White House Office of Management and Budget in 1990. Comprising representatives from all government agencies that use or handle geospatial data, the committee is working with industry and academia to create standards and procedures for a National Spatial Data Infrastructure (NSDI). Dozens of federal and state agencies, universities, and private vendors already offer geospatial data for free or at relatively low cost (2). An increasing amount of the data is available online. USGS, for example, provides many varieties of cartographic data, including topographic and hydrographic information, land use and land cover data, and multispectral photography from Landsat and other remote-sensing satellites. Among the projects now under way at USGS is the production of 3.75minute orthophoto quadrangles digital images based on aerial photographs for which displacements caused by the camera and terrain have been removed. The photographs can be used as GIS base maps instead of illustrated maps. Government agencies often take one another's raw data and adapt it or add value. USGS hydrologic data, for example, are the foundation of EPA's "Reach" files, a digital database of the nation's surface waterways created in the 1970s at a scale of 1:500,000. An improved version, "Reach File 3," is expected to be completed this year with a scale of 1:100,000. Users will be able to view any river or stream (identified by name or location) and see its relationships to an entire drainage network, upstream and downstream. Several environmental researchers already have combined transport models with the Reach database to track the fate of pollutants and nutrients in a watershed. Using this method, USGS scientists have shown that pollution often originates outside the state where the problem resides. The U.S. Departments of Agriculture, Defense, and Energy all maintain geospatial data archives, and the Census Bureau has its own nationwide TIGER (Topographically Integrated Geographic Encoding and Referencing) database, which digitizes state, county, and local boundaries, school districts, highway designations, and census results. EPA developing U.S. land cover data EPA itself has a large amount of digital geographic data available for environmental researchers and the public, including information on Toxics Release Inventory (TRI) sites, air monitoring locations, nonattainment areas for air quality regulations, and current and proposed Superfund cleanup sites (3). One current EPA project is to make land cover maps based on Landsat Thematic Mapper (TM) satellite images available for GIS applications. The TM images, taken in several spectral bands, can be used to identify different types of vegetation and assess their health. The land cover maps, with a resolution of 30 m, already

Environmental impact statements

Air quality modeling of sulfur dioxide at U.S. Army base. Conducting a comprehensive environmental impact study (EIS) for a 100-square-mile Army base, the Aberdeen Proving Ground on Maryland's Chesapeake Bay, would be no easy task under any circumstances. But, says James Kuiper of the Argonne National Laboratory, who was a GIS technical leader for the project, "GIS technology helped us tremendously with the project." Building the GIS database took a year, as the team sifted through hundreds of existing documents and data, much of it containing good information but little of it easily accessible for integrated analysis and decision making. Along with physical data about the site, the diverse information fed into the database ranged from locations of bald eagle nests to aircraft noise models to locations of archaeological sites. Once analysis began, the team could easily make many crossdisciplinary connections using GIS. Watershed boundaries and 100year flood contours produced for hydrological studies were used by waste management specialists for risk assessments. Ecologists and archaeologists used noise-modeling results to consider effects on wildlife and historic buildings. The final EIS products will include more than 250 GIS-produced maps and an extensive environmental database for Aberdeen site managers to use in the future,

are available for the Mid-Atlantic region, and maps for the rest of the United States are expected to be available by the end of 1997. These should be useful for ecological and habitat studies, particularly those that track changes over time, such as accelerating deforestation. In addition to providing data for outside consumption, EPA uses GIS to coordinate geospatial data agencywide, says Andrew Battin of EPA's national GIS office. The lack of such coordination became obvious during the Midwestern floods of 1993. Attempts to gain a clear picture of which regulated facilities had been affected by the flooding were hampered because the maps for one EPA region did not match the adjoining region's. By digitizing and sharing base maps in a common GIS, the agency now has a "100% seamless concept," in which information can be shared freely among the regions. States and localities are also beginning to make geospatial data more widely available. One example is North Carolina, whose Center for Geographic Information and Analysis has compiled a wealth of local GIS-compatible information, from county soil data to hazardous waste disposal sites in the state (4). Commercial vendors of geospatial data are also VOL.30, NO. 8, 1996 /ENVIRONMENTAL SCIENCE & TECHNOLOGY / N E W S * 3 4 1 A

Farm runoff

"Agro-ecoregions" of the Minnesota River, based on soil drainage, geomorphology, and slope steepness data.

The Minnesota River basin, which drains nearly 15,000 square miles of mostly farmland in 12 major watersheds, has been ranked as one of the 10 most polluted rivers in the United States. Researchers at the University of Minnesota and other institutions, under the sponsorship of the state department of agriculture, are using GIS to gain a better understanding of the principal nonpoint sources of pollution.

The GIS database incorporates a variety of attributes, including slope steepness, erosion potential, and proximity to lakes and streams. Considering all these factors together has led to the identification of different "agro-ecoregions," each of which might have its own preferred method of reducing the pollution problem, says Ananda Mallawatantri of the University of Minnesota. The GIS work has been fairly straightforward, he says; "Nothing surprising, just a simplification of the analysis process." But the GIS-generated maps also have helped present the information in understandable ways to nonspecialists, particularly farmers, who ultimately will be the ones to implement the new agricultural practices.

Groundwater monitoring sites EPA is choosy when it comes to approving sites for groundwater monitoring studies in connection with the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), which regulates pesticides. EPA requires that a monitoring site meet specific criteria for soil type, depth of ground water, and history of crop planting and pesticide use. Because of these multiple requirements. Stone Environmental, Inc., a consulting company in Montpelier, Vt, recognized FIFRA site selection as a prime candidate for GIS integration. Pulling together soils data and crop acreage statistics from the U.S. Department of Agriculture, along with county soils data and other geologic and hydrologic information, the company produced an atlas of areas that meet FIFRA groundwater siting criteria.

Potential groundwater monitoring sites for the state of Georgia, based on soil characteristics.

proliferating. Generally these companies, like Environmental Database, take publicly available information and enhance it by including proprietary data or by repackaging the information and tailoring it to specific markets (5). Several commercial satellite systems also will be launched in the next few years to provide high-resolution (1-m) satellite imagery, which 3 4 2 A • VOL. 30, NO. 8, 1996 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS

can be used in GIS. Not only is GIS affecting the way geospatial data are analyzed, it is changing the way data are collected. Inexpensive and portable global positioning system (GPS) receivers, which use satellite navigation to pinpoint a location, are now commonly used in field operations to provide accurate digital data for use in a GIS model. Lightweight "pen" computers and speech recognition software also can be used to produce digital field notes that can easily be plugged into a GIS database. The result, according to Goodchild, is that "the database becomes the product of GIS, rather than its input." One example of this shift is an environmental remediation project at The Presidio, the famed San Francisco military base now converted to a national park. Part of the job has been to characterize lead contamination at eight historic firing ranges, which have been closed for more than 30 years. The trouble was, until recently, no one knew exactly where they had been. Maps dating to the 1880s showed the boundaries of the old ranges, but in only one case were any physical indicators left. So a team from the U.S. Army Corps of Engineers and the San Francisco office of Montgomery Watson, Inc., an environmental consulting company, digitized the historic maps using a computer-aided drawing (CAD) program. Then they overlaid that map on a modern one using GIS software. Digital map in hand, field workers armed with GPS receivers used the coordinates to stake out the boundaries of the old ranges. Next, X-ray fluorescence sensors sampled every 120 ft for signs of lead. Each reading was duly pinpointed using the GPS, and the recorded levels and location were loaded into the GIS model to build a 3-D map of the lead plume in near-real time. Using conventional surveying techniques, says Kimberley McDade of Montgomery Watson, "would have been a lot more expensive, and it wouldn't have been as accurate."

GIS merging with other software As GIS becomes more common in environmental and other applications, it is being incorporated into more mainstream types of software. New versions of CAD and database programs such as AutoCAD and Oracle, for example, include the ability to analyze and manipulate GIS data. Some companies have used GIS as the foundation for more comprehensive software packages designed specifically for environmental uses. GIS\Solutions, Inc. (Concord, Calif.), has developed an environmental data management system named GIS\Key, tailored to assessment and reporting at hazardous waste sites. The program merges GIS, database, and CAD capabilities and stores and integrates chemical, hydrological, and geological data, as well as other types of information. The company reports that GIS\Key users, which include NASA's Ames Research Center and DuPont Chemical, report a 30-60% reduction in costs associated with site investigation and compliance. As with any technology, GIS has its limitations. Historically, users have had to spend significant amounts of time converting maps and other data sources to GIS-usable formats. Once the conversion is done, the information can be manipulated in

powerful ways. Still, says Goodchild, "GIS-based projects when considered in their entirety are often significantly slower than ones completed using more traditional methods." The increasing availability of digital data should improve this situation. Using GIS with existing environmental modeling tools is another potential rough spot. According to Karen Kemp of the NCGIA, "There is often a conceptual mismatch between the analog data models used by environmental scientists when they collect real-world data and the digital data models offered by GIS" (6). Longstanding models for such environmental processes as groundwater transport or soil loss also will need to be modified to incorporate GIS-produced spatial data, say many advocates of GIS technology. The danger of overinterpretation Then there is the danger of overinterpreting GIS products. Lehnertz gives the example of radon risk maps for large areas, which tell an individual little about the situation in a single home. Any user of GIS needs to know the assumptions that went into creating the map, including the scale and quality of the original data. At the same time, another digital technology, the Internet—and particularly the World Wide Web— affords GIS the opportunity to reach a much wider audience, not only in the environmental community but among the public. Several projects are under way to collect a large amount of geospatial data under a single online "roof," among them the Alexandria Digital Library at the University of California at Santa Barbara (7). This Web site, which is still being tested, will allow users to browse and retrieve maps, imagery, historic aerial photos, and other GIS-compatible data. Other groups are using GIS technology to generate digital maps "on the fly" over the Internet, primarily as a means to disseminate public information about the environment. The British-based Friends of the Earth, for example, sponsors a Web site where users enter their postal code on a search form and immediately get a map showing past chemical releases in their neighborhood (8). EPAs "SITEINFO" Web site, currently available only for the northwestern states (9), offers a similar service for the U.S. public; GIS is used to generate maps displaying a wide range of environmental factors, from local wetlands to Superfund sites. EPA calls this concept "Maps on Demand" and recently unveiled an ambitious example in its "Surf Your Watershed" Web site (10). Environmental professionals and the public can locate and view their own watersheds (after searching by name or by coordinates), view them at different scales, and generate maps showing different environmental themes, such as air quality or ecosystem protection. In addition to the maps, the various layers of digital GIS data also are available for downloading. Perhaps most important, says Karen Klima, who is working on the site for EPA's Office of Water, is the ability of localities and researchers to link their own data on individual watersheds to the Web site through an easy-to-use, fill-in form. "What we really need is all the local information," she says, which in many cases is more detailed than data collected on a larger scale by federal and state agencies. University researchers, for example, might link their own Web sites, or even provide access to their own data.

Oil spills Standard GIS software is often modified or enhanced to tackle specific jobs, sometimes spinning off new standard products in the process. In 1994, the Magnavox Electronic Systems Company teamed up with the Environmental Systems Research Institute, makers Managing the impact of a hypothetical of the industry-leading Arcoil spill in the Gulf of Mexico View GIS program, and Jamestown Marine Services to create an integrated program that could help in the management of oil spills. The result, the Oil Spill Response Management System, allows everyone involved in a cleanup operation to read simultaneously from the same electronic map, no matter what the location. The system combines up-to-the-minute data on ocean and weather conditions with spill trajectory models and baseline data provided by several agencies. The interactive system can be updated in real time with satellite images and even includes the capability to track costs as the cleanup operation progresses.

Apart from an increasing presence on the Internet, the next step in the evolution of GIS, says Denice Shaw of EPA's Office of Research and Development, is to merge 3-D GIS applications with computerized techniques for "scientific visualization," which adds the fourth dimension of time. This convergence, which is just beginning, will eventually produce rich, 4-D animations showing complex environmental processes, such as nutrient flow in an aquatic ecosystem, varying in space and time. Shaw sees this as a natural extension of GIS, particularly as more users become familiar with the systems. And that is happening, she says. "I've had to fight for years to get people to appreciate what GIS could do. And I'd say the past two years have been revolutionary; now everybody is viewing environmental data from that perspective." References CD List of GIS software packages: http://triton.cms.udel.edu/ —Oliver/gis_gip/gis_gip_list.html. (2) Federal Geographic Data Committee Internet site: http:/ /fgdc.er.usgs.gov. (3) EPA Internet data sites: http://nsdi.epa.gov/nsdi and http:/ /www.epa.gov/docs/grd. (4) North Carolina Center for Geographic Information and Analysis: http://cgia.cgia.state.nc.us. (5) GIS data publishers: http://www.esri.com/products/ arcdata / publishers.html. (6) Kemp, K. Presentation at the Third International Conference/Workshop on Integrating GIS and Environmental Modeling, Santa Fe, N.M., lanuary 1996. (http:// www.ncgia.ucsb.edu/conf/SANTA_FE_CD-ROM/ sf_papers/kemp_karen/kemp.html). (7) Alexandria Digital Library: http://alexandria.sdc. ucsb.edu. (8) Friends of the Earth: http://www.foe.co.uk/index.html. (9) SITEINFO: http://www.epa.gov/regionlO/www/ siteinfo.html. (10) Surf Your Watershed: http://www.epa.gov/surf/.

Tony Reichhardt is a contributing editor o/ES&T based in Fredericksburg, Va. His article on environmental Internet resources appeared in the February 1996 issue. VOL.30, NO. 8, 1996 /ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 3 4 3 A