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GPS is a system of 24 satellites in the Earth’s orbit combined with ground-based receivers. Originally developed by the military, GPS is now available for people from hikers to drivers to government planners. The operation is based on the same laws you learned in high school geometry. The satellites continuously transmit signals. When a person with a GPS receiver wants to know his position, the receiver "finds" at least three satellite signals, then calculates the amount of time for each signal to reach it and determines the distance to each satellite. When the distances are calculated from three satellites, an exact position can be determined.

Map of Bull Trout habitat and facility discharge to the Bitterroot River

GIS operates on the level of Earth. GIS is a system of hardware and software tools that allows a user to integrate and visualize spatial data into a grid system. By overlaying different data, such as land use, soil types, storm runoff, and water quality, connections and interactions appear that might not be obvious on a flat map.

The most common GIS formats are found in the Arc family, developed by Environmental Systems Research Institute (ESRI). They include ArcView, ArcInfo, and ArcScript, a presentation application. Arc systems run on many computer systems, including Windows, Unix, and Linux.

The Geographic Resources Analysis Support System, commonly referred to as GRASS, was developed by the US Army Construction Engineering Research Laboratories for use by the military. The GRASS team now has headquarters at Baylor University in the United States and at the University of Hannover in Germany. GRASS has an intuitive Windows interface and can run on several Windows operating systems.

The biggest challenge with either type of system is getting the data into the right format. Data from such various sources as land-use maps, tax assessments, watershed information, photographs, and satellite imagery can use many different measurement types. The first chore is to produce compatible data, usually in a digital format, to input into the GIS. Once the data are in the system, however, they can be updated easily.

Digital data that can be used in a GIS include the following:

• raster quad maps
• digital elevation models
• land-use maps
• soil data
• precipitation runoff amounts, such as from Hydrologic Engineering Center’s Hydrologic Modeling System
• Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) data
• Soil and Water Assessment Tool (SWAT) data
• Stormwater Management Model (SWMM) data
• water-quality readings
• photographs and satellite imagery
• GPS location data

Many of these can be obtained from such government agencies as EPA, the Natural Resources Conservation Service, and the US Geological Survey.

One big advantage of GIS is that it can be customized by the user. A watershed management professional will use different data and produce different models than a stormwater manager. The watershed manager will probably use layers of information about rainfall and runoff, sediment yield, nonpoint pollution sources, and water-quality monitors. Many of these may have locations pinpointed by a GPS and integrated into the GIS. The stormwater manager will have layers of building footprints, sewer-system maps, and land-use maps. Each can produce reports and three-dimensional visualization of the information in the database.

The following case studies demonstrate the variety of uses for GIS and GPS. Each entity has determined its needs and customized the systems to meet them.

MontanaView

Map of Boulder River hydrologic unit showing impaired streams

The State of Montana wanted to build a GIS-based system to allow the Department of Environmental Quality (DEQ) to analyze watershed management techniques, assess total maximum daily loads (TMDLs), and protect water quality. Velda Welch, water information specialist with the DEQ, states that ArcView was chosen because "it was more user-friendly and easy for the public to use."

Using funding from EPA, a system called MontanaView was developed in 1998-1999. The system had ArcView as a foundation and was customized to be Montana-specific. William B. Samuels, from Science Applications International Corporation in McLean, VA, worked on the integration of the data systems. "The biggest challenge was that the data were in different systems, different platforms, and much of it not GIS-compatible," he says. Data used included demographics, land-use information, natural resources, and infrastructure. Now that the data are incorporated into MontanaView, Samuels points out, "It allows analysts to visualize the various layers and relate impaired water resources to the source of the problem."

One advantage to GIS is that it speeds up routine tasks. "One of my main jobs has been to synthesize maps of different water bodies in the state of Montana," says Stacy Diekhans, an environmental-quality intern with the DEQ. "It is important for these maps to contain information about surface water, mine locations, geographic place names, et cetera around the water bodies. Without MontanaView, generating these maps would be very tedious. The time that it would take me to make one map would probably go from 20 minutes to at least a day."

One of the DEQ’s objectives was to increase the ease of public access to information, especially on such topics of interest as water quality and TMDLs. Perri Phillips, a staff member in the TMDL Monitoring Section of the DEQ, uses data contained in the system in reviewing the history of water bodies on Montana’s 303(d) list–those identified under section 303(d) of the Clean Water Act as having impaired water quality. "MontanaView provides water chemistry, physical and field parameter data, and data distribution, which we used in conjunction with habitat information and biological data from other sources to make water quality—impairment determinations. It also provided us with land-use information, which enabled us to appropriately segment streams based on changes in land use. We were also able to identify potential pollution sources, such as abandoned and active mines. MontanaView maps facilitated our identification of correlations and interrelationships among data sets and information, as well as among pollutants and potential sources.

"We have inserted hard copies of MontanaView water-body maps in each of the TMDL files as essential documentation of our impairment determinations. The maps are excellent overviews of each water-body drainage and enable concerned citizens to quickly discern information within its proper spatial context, in lieu of rummaging through numerous pages of analytical data. These maps are also excellent visual aids during public meetings."

Welch says that the state of Montana has moved further since the unveiling of MontanaView, developing a Web-based, interactive program called (for now) "the mapper application," also based on GIS. The original MontanaView required one gigabyte to be installed on a desktop computer. Users can access the new system through the Internet and do not have to have ArcView on their computers to receive information. A user can define an area of interest, such as a watershed or a single stream, and the program will generate reports. So far, other state agencies have been the number-one client for the new system. There are plans to take a survey to identify other users and the type of data they require.

Welch has been involved in the Montana Drought program. Usually drought assistance is determined by county. Montana has large counties, however, some bigger than the size of many states. If data are gathered only from points in a county, the resulting analysis might show no drought. By using GIS to define multiple points, a different picture of severe drought can emerge.

The new GIS-based system will also receive updates regarding water quality and erosion based on the fires of 2000. Montana has volunteer water monitors who collect data and upload them to the state. This dynamic water-quality information gives environmentalists a "warning light" before a problem can fully develop. For this network, GPS also comes into play, pinpointing the locations of the monitoring stations.

Montana is also making the system available to educators and students; the Web site includes tutorials and graphics for students from kindergarten through college.

Coastal Uses

Map of Yellowstone River showing dischargers, water supplies, and stream flow data

In 1989, Hurricane Hugo struck the coast of South Carolina. The Office of Ocean and Coastal Resource Management (OCRM) personnel attempted to assess storm damage, but because the damage was so extensive, they had problems orienting themselves and identifying damaged structures. Since that hurricane, South Carolina officials have developed a GIS-GPS protocol to facilitate damage assessment. The eight coastal counties use the new system built with grant money from the National Oceanic and Atmospheric Administration.

"Knowing what’s there on the beach before a storm hits is half the battle," says Douglas Marcy, an intern with OCRM. He developed a plan to take GPS position readings of houses, docks, and sea walls along the coast. A handheld GPS unit contains a data dictionary that also allows a person conducting an inspection or reviewing sites for permits to input information that keeps the system updated. Back in the office, that information is added to ArcView GIS, which also contains tax information, such as property owners and addresses. Bill Eiser, GIS manager for OCRM, states that many beachfront-property owners do not live on the property full-time, so contacting them in the event of a storm is critical. Other GIS layers include aerial photographs, maps, and cadastral data. Erosion control devices as well as structures are indicated.

If and when the next hurricane hits South Carolina, damage assessments can be carried out more efficiently and quickly. Marcy produced a CD-ROM tutorial on how to use the GIS-GPS damage-assessment protocol, and personnel try to review it at the beginning of each hurricane season so they can be current when the storm occurs. "We haven’t actually tested the system yet because we haven’t had a hurricane," says Eiser.

South Carolina’s OCRM is also using GIS on an everyday basis. The system allows easy review and comparison of permits, such as for a dock or a marina. To provide consistency, the system compares the new request to permits approved in the past. Most importantly, the system is loaded with information on endangered species and archaeological sites. It will raise a red flag if a new permit interferes with habitats or known archaeological sites. "I wear two hats," relates Eiser, "GIS manager and oceanographer." But he foresees that soon there will be a need to separate these two jobs because of the increase in GIS information and use.

Prince William County

Prince William County, VA, set up a countywide GIS based on ArcInfo. The system is used for drainage-system inventory, National Pollutant Discharge Elimination System (NPDES) permit compliance, and watershed management, as well as to help set stormwater fees. Data input includes soil types, storm-drainage outfalls, and inspection points, including erosion control devices.

The digital layer of soil types identifies areas that require geotechnical analysis before development, taking much of the guesswork out of that process and making it unnecessary to do extensive studies on all land. It also marks highly permeable or highly erodible soils that must be monitored. Mark Colwell of the county’s Department of Public Works states, "By utilizing GIS, the digital layers of mapped features are readily available for use and can be easily revised or updated." The staff uses the system to review development plans and perform hydrologic analysis.

Inspections were performed on about 250 stormwater management devices and easements, and the results were added into the system. The maps allow maintenance crews to quickly locate pipes and other structures for repair. This system also allows operators to review permit applications for compliance with NPDES in a more efficient way.

Watershed modeling is also an important facet of the system. Officials in Prince William County have developed models with input from the HEC-1 and HEC-2 models. Using the system is much less time-consuming than gathering data by hand, produces a more detailed picture, and allows "what-if" situation modeling. Three watersheds were chosen for testing, and the process went so well that it will be implemented in all 32 watersheds.

The Chesapeake Bay Resources Protection Area boundaries are also set by GIS. Composite data layers of soils, environmental resources (e.g., wetlands), streams, steep slopes, and wildlife habitat allow operators to visualize potential environmental problems and prevent them.

Prince William County also has used GIS for setting stormwater management fees. The impervious areas of 80,000 parcels were determined and added to the system. These areas can be updated continuously as development continues. Stormwater fees are based on the impervious area of a parcel of land, which relates to the runoff that will occur.

Planning in Spokane

Reach File map (Basin Creek) showing linkage to the beneficial-use/use-impairment database and Montana Rivers Information System

Stormwater management and city planning are the major uses of GIS in Spokane, WA. The city also needed to implement planning for compliance with the Washington State Growth Management Act. Officials decided that GIS best fit the bill. The city, along with ESRI and engineering company Merrick and Company of Aurora, CO, developed a plan to cover these different needs.

Spokane is a city with a population of about 200,000, with neighboring urban areas that add about 100,000 more. The city uses the ArcInfo software with UNIX hardware. Lars Handron, senior engineer with the Capital Programs and GIS Division, says one very important consideration was that the systems be compatible with county hardware and software. The city and county ensured compatibility by using the same systems and sharing information through data licenses. Although the initial use of the ArcInfo system was for stormwater management, it is presently expanding to include sewer maintenance, NPDES compliance, and water-system management. GIS programs are also used for a fire department atlas, a public-safety dispatch system, and the parks department.

Sewer maintenance is being handled more cost-effectively by a combination of GIS and the Hansen asset management system. The system contains work orders, locations, and data on work done. Handron says that the big advantage is knowing what a project costs as you go, not at a later date. "Also, we know where to increase maintenance costs and where to reduce them."

GPS is also in use in Spokane. The city hired Merrick and Company to produce topographic data sets using flight photos and satellite positioning data. Frank Somarriba, project manager for ESRI, reports that a test by the water department proved very useful. The project surveyed water valves and hydrants and updated manhole positions. "The challenge is to resolve inconsistencies in the paper data," he says. "There is always room for improvement."

Handron agrees, saying, "We need to focus on data management now. Some of our information is getting a bit out of date and needs to be updated." The city is expanding its use of GIS into other departments. Handron predicts a slow, steady growth pattern. "We want to make sure we have a good, solid implementation." The city has obtained GPS receivers within the last year and is beginning to use those to convert old data into GPS information compatible with the GIS programs. Handron states that might take up to a year for the conversion. An engineering study has been done to confirm the location of facilities, such as storm drains and sewer pipes. The city expects to expand use of the system to the water department soon.

Stillwater

The Village of Stillwater, NY, put GIS capabilities to good use after it requested a study of its aquifer from the Capital District Regional Planning Commission (CDRPC) in Albany. The aquifer is the sole drinking-water source for the village, but no protection laws were in place. Data were collected about residential properties using septic tanks, a fuel storage depot, and other potential pollution sources. Using ArcView, these data were superimposed over a map showing the location of the aquifer. Todd Fabbozi of CDRPC reports, "Most people had no perception of a problem. Then they saw the overlays of the land use and permeable soils, and the potential problems really jumped out." The village has instituted an aquifer protection law, and work on connecting those residences to a local sewer system is continuing.

Many other government entities of all sizes are implementing GIS and GPS to improve their planning, permitting, and management capabilities. Fort Worth, TX, has instituted a GIS that includes graphical user interface—generated forms to be filled out by inspectors when viewing industrial sites and construction sites to determine compliance with stormwater pollution-prevention plans. The information is stored in an ArcView database and can be accessed to see how industrial facilities are impacting watersheds.

The City of Atlanta is using GIS and a hydrologic and hydraulic software called Hydra, developed by Pizer Inc. of Seattle, WA, to coordinate a watershed management program. The plan includes such information as land use and development, stormwater and sewer systems, and the potential impact of future development. The visual aspects of the GIS programs make tremendous amounts of information understandable to city planners and officials at all levels.

Even rural entities are tapping into GIS and GPS to handle pollution-prevention and restoration efforts. The Otter River restoration project in Michigan consists of a GIS foundation to keep track of restoration efforts and results. Prevention of sediment pollution was the main goal. A database with site reports, restoration techniques, work orders, permits, and hydrologic analyses can be accessed through the Internet.

The use of high-tech tools such as GIS and GPS will continue and expand as more communities develop customized tools to aid in carrying out many management functions. As cities come to rely on all the information readily available through these tools, the demand will only increase.