Geographic Information Systems

Transcription

1 Jan Coyne, William C. Bell, Mary Maureen Brown, Chad Rupert, and James Nolan Geographic Information Systems A geographic information system (GIS) combines database management and analysis functions with computer-aided mapping. It adds a visual and locational dimension to municipal management and decision making. Since much of the data municipalities manage is land based, a GIS can help managers and decision makers manage municipal affairs more effectively. With the correct data, a GIS allows users to ask questions such as the following: What is at this location? Where are the underground utilities located? Where should new infrastructure such as fire hydrants be located? What is the address of this parcel? What is the average income in the municipality? What areas of the municipality are suitable/unsuitable to build on? What is the pattern of land-use change? What is the best route for service-delivery vehicles (emergency or general)? This chapter provides an overview of GIS technology and discusses the issues involved and the potential for GIS to help municipal governments make better decisions. GIS technology is widely used in local

2 2 Geographic Information Systems government, either as an in-house service or as a service provided by other public-sector organizations or private firms. GIS technology is also used by businesses, nonprofit organizations, and community groups. Whether or not a municipality uses a GIS, chances are that municipal decision makers will encounter the products of GIS technology. Implementing and managing a GIS requires a level of funding that may seem unwarranted without some knowledge of why the funding is necessary and what the benefit is to the municipality. Knowing the limitations and capabilities of GIS technology allows municipal decision makers to use it economically and effectively. WHAT IS A GIS? A GIS is a system of hardware, software, geographic data, and experienced personnel whose purposes is to support the capture, management, manipulation, analysis, modeling, and display of spatially referenced data for solving complex planning and management problems. In other words, it is a computer system that is used for collecting and analyzing data that can be mapped, and it displays the resulting information as a map or series of maps. Spatially referenced means that the data displayed on the computer screen are tied to a real-world location; that is, the latitude and longitude of a feature on the ground (such as an intersection) would be automatically reflected on the onscreen map. Spatial Data Types of spatially referenced data that a municipality would use include the following: Jurisdictional boundaries county and city limits special services districts census divisions property boundaries electoral districts parks

3 Geographic Information Systems 3 Physical features roads utility lines and other features buildings land use (residential vs. industrial, for example) The spatial data are linked to attribute data in a database. Attribute data refer to additional information about a feature such as the name and length of a road, the size and pressure capacity of a water line, and the owner and value of a parcel. One way municipal information is organized in a GIS is by layers of spatial features with their attributes (Figure 1). These layers can then be presented singly or overlaid with other features, depending on what information is being sought. For example, the roads, land-use, and facilities layers can be overlaid to see where the best location for a new fire station might be. It is this ability to integrate disparate types of data and display the relationships between and among them that makes a GIS powerful. Data that are useful to a municipality can take significant amounts of time and money to acquire. Although free digital data are available from both state and federal governments, the usefulness of such data for local governments may be limited due to lack of scale or spatial accuracy. The GIS user must be aware of differences in spatial accuracy in order to determine whether or to what degree the results of analysis should be trusted. For example, FEMA flood data that are used in conjunction with parcel data, which have a much higher degree of spatial accuracy, should be interpreted cautiously. Related Technologies A GIS can be developed as a general-purpose tool or for a narrowly defined set of functions. For example, a land information system (LIS) focuses on the mapping and analysis of land and property records. Transportation management uses a specialized set of analysis tools supplied by developers of GIS technology for transportation. Other automated mapping systems were developed for specific fields that are now incorporating GIS functions. These include computer-aided drafting (CAD), widely used in industrial design and architecture;

4 4 Geographic Information Systems automated mapping/facilities mapping (AM/FM), used to manage utilities; and global positioning system (GPS). The latter system, GPS, includes receivers and satellites that can pinpoint locations on the earth. It is used in the computerized navigational systems found on boats and in some automobiles. Surveyors use GPS to help them make more accurate surveys. It is one way to collect sufficiently detailed data for a municipality or to check the accuracy of data acquired in other ways. Figure 1. Map Overlay Potential of a GIS MAP LAYERS ASSOCIATED DATA Zoning Layer Utilities Layer Topographic Layer R-1 R- 2 R-15 No Size Year Mat. Depth Press. Ins. by Ins. no. Parcel Layer 12 Planimetric (or base) Layer State Plane Reference Grid No Owner Address L.B. P. Land value Bldg. value Prop. code Bldg. code Zoning Stories Garage Area Frontage Last sold Geodetic Survey Control Layer

5 Geographic Information Systems 5 Remote sensing is the acquisition of data from satellites or airplanes using infrared sensors, radar, Light Detection and Ranging (LiDAR), 1 cameras, or other sensors. Once adjusted, images can be used for interpreting land-use patterns over wide areas or for updating and checking the accuracy of other map layers, such as land cover or land use. GPS, remote sensing, and air photography are technologies that enable municipalities to create sufficiently detailed and accurate data for the scale of a municipal-level GIS. The expense of acquiring the imagery or hiring a surveyor is part of the reason why data acquisition can be one of the more costly aspects of GIS implementation, usually second only to the salaries of GIS personnel. LOCAL GOVERNMENT APPLICATIONS The strength of a GIS lies in its ability to combine both visualization and analytical functions. The combination of maps and graphics with a relational database is a powerful tool for managing information. A GIS can integrate diverse sources of information that create patterns and relationships that might otherwise be missed. Patterns of population growth, road networks, waterways, or vegetation distribution can be compared with one another. Hypothetical scenarios, such as how the landscape would look with different levels of population growth or different land-use policies, also can be seen. An individual attribute can be viewed in multiple ways: with more or with less detail, alone or with other attributes, or in its current, past, or possible future state. For example, data can be classified or abstracted before being displayed to show an average or number of entities above or below a certain threshold. Initially, GIS technology was predominantly used to automate manual tasks already being performed in local governments, such as mapping and information management. Current systems allow more complex analyses of data, including three-dimensional visualization of landscapes and forecasting. Researchers and practitioners are also investigating ways to incorporate GIS technology into the public participation process so that citizens and decision makers can benefit from the technology throughout all phases of planning and policy creation. GIS technology can be applied to the following functions of a municipal government, among others: public works water works

6 6 Geographic Information Systems elections police tax assessment solid waste management planning and zoning natural resources emergency services management parks and recreation transportation planning In addition, the availability of a GIS can directly affect citizen participation, particularly with regard to taxation issues: A GIS can be used to analyze the relationship between tax revenues drawn from different neighborhoods or areas and the expenditures being made in those areas. Citizens can use the GIS to learn how taxes drawn from their neighborhood are budgeted for different functions. As recent surveys suggest, citizens are more likely to approve of needed taxations when they know that their dollars are being spent on specific services especially services that might benefit their neighborhood or themselves individually. 2 Data can be analyzed in order to reveal patterns or trends that need to be addressed or to assess the impact of a municipal policy. For example, where and when certain types of crime occurs may be associated with land use (does it occur in residential or business areas? does it occur at the same general time? is it concentrated in one area or widely dispersed?), proximity to transportation, population characteristics, and other information that law enforcement agencies can use in deciding how to focus their efforts. Such data may suggest other solutions, such as installing streetlights in dark areas or providing crime prevention education for citizens.

7 Geographic Information Systems 7 A GIS can be used to help decide which of a number of possible changes might be the best one(s) to implement. For example, population growth trends can be modeled in terms of land-use or zoning regulations to see how each might affect the municipality in terms of infrastructure requirements. Regulations can be changed, land-use or zoning types can be shifted, and the effects can be assessed to help evaluate whether current regulations will be viable in the future. BENEFITS AND COSTS OF IMPLEMENTING GIS TECHNOLOGY Cost savings can be very difficult to quantify. For example, cost savings were realized when local governments converted from paper-based systems to computer-based systems, but just how much was saved? The use of GIS technology in small jurisdictions has become commonplace only in the last two decades. Larger local governments, such as those in major urban areas, were early adopters of the technology and have been the focus of studies of the effectiveness and costs and benefits of using GIS technology. The results of these initial studies were based on the early use of GIS technology to automate tasks, which was considered a beneficial function. The studies indicate that there is not necessarily an immediate return on investment; jurisdictions generally began seeing cost decreases and efficiencies in three to five years. Other benefits of GIS technology adoption include eliminating duplication (i.e., one database can serve multiple users, and therefore fewer opportunities exist for the introduction of human error) and improving data management, information processing, access to information, analysis and problem-solving capabilities, and the quality of decisions because they are backed by sufficient data. Greater efficiencies in answering citizen inquiries through GIS can result in savings for a local government. Continued software innovations, such as advancements in GPS technology and reduced costs of aerial photography, have resulted in lower data-acquisition costs. This greater access to data has made it possible for even the smallest jurisdiction to develop a GIS. In the past decade, there has been a surge in the development of GIS Web sites, where citizens can view tax records to verify the correctness of information used in the assessment process or determine if they are being treated fairly compared with other taxpayers. Besides tax parcel information, these Web sites often host GIS data related to zoning, road networks, aerial photography, rivers and streams, and a variety of other features. They allow the general public to answer their own questions without assistance from government employees.

8 8 Geographic Information Systems Aside from the fact that improvements may not be apparent for years, part of the difficulty in measuring the benefit of a GIS is that much of it is not quantifiable. It is hard to separate the effects of the system from the effects of its environment. Local governments benefit from GIS and other technology when the implementation of it is well researched and planned. The purpose of the system needs to be clear, and those responsible for managing it need to be trained in its use. The jurisdictions that have been disappointed in their return on GIS investment have generally not done enough groundwork to understand all of the costs involved, or they have not received the appropriate level of employee training to properly use and maintain their system. Local governments, regional commissions, and local authorities are permitted to charge fees for providing information from or access to their GIS. Fees must be based on the development costs of creating or maintaining the GIS and may include cost to the municipality... of time, equipment, and personnel in the creation, purchase, development, production, or update of the geographic information system. The code also authorizes local governments to contract with private firms to provide GIS information to the public. 3 The costs of adopting a GIS vary with how much is required of the system, whether new people need to be hired, and, if so, how many. Expenditures for GIS software range from applications having little or no cost to applications costing tens of thousands of dollars that run on computers ranging from inexpensive desktop PCs to massive networked servers. Other than ongoing salary costs, initial database development is usually the most costly aspect of GIS implementation both in terms of funding and time, and it varies with the amount and detail of data needed. Regular hardware, software, and database upgrades need to be considered in the long-term budget for a system. Municipalities change, as do the data about them, and the uses of the GIS will change as well. Personnel training is often neglected when considering costs. Initial training and periodic updates are necessary in order for the system to be fully utilized. There is no point in paying for functions that the staff is not aware of or able to use properly. Implementation The first step in considering adoption of a GIS is to decide what kinds of analysis a municipality wants to perform and what information it wants to obtain from the analysis. The next step is to conduct a cost-benefit analysis and feasibility study. These studies should address more than just technical issues, since organizational and policy issues play a role in

9 Geographic Information Systems 9 implementation. Employee receptivity to technology and ability to adapt to new technology, how effectively potential users of the system communicate, and users conception about what is wanted and needed in the system all affect how much a GIS costs and how long it takes to implement. All potential users of the system should be consulted at this stage to make sure that all data needs or requirements are taken into account. Once the decision to adopt a GIS is made, the municipality needs to decide how to organize it. There are a number of organizational models of GIS implementation: single department, multidepartment, or multiagency. Single Department Model In the single department approach, the GIS is developed in a single department of the government and used only for the applications of that department. This approach is common. For example, the municipal planning department may develop a GIS to manage land records information. As other departments learn about the system, they may request GIS services from that department. Multidepartment Model In this model, various departments share costs and responsibilities. Cost sharing among the departments funds database development and updating. Sometimes this model evolves from the single department model as requests for service impede the use of the system for its original purpose. There are a couple of approaches to the multidepartment model. One department may be chosen as the lead department and be responsible for housing the GIS and providing the services to other departments. The other approach is to create a GIS department to manage the system. Both approaches have advantages and disadvantages. Having a lead department with its own priorities may affect how service is provided to other departments, and a centralized GIS department may not be able to respond to the specialized needs of individual municipal departments. Multiagency Model The multiagency model shares costs and responsibilities between several levels of local government or between a number of partners governmental or nongovernmental. Typical agreements involve utilities such as gas, power, cable, and telephone companies that share the cost of data development with municipalities and exchange information such as underground structures data with them. If there is sufficient interest on behalf of the partners, this approach is the most economical option.

10 10 Geographic Information Systems However, with this model, it generally takes much longer to get projects under way because of the need to conduct joint discussions on cost sharing and to consider different kinds of data, different levels of accuracy, and the different viewpoints and politics of the various agencies. Nevertheless, the greater variety of data provided by multiple partners yields better benefits at lower costs (Figure 2). Figure 2. Multiagency GIS Law Enforcement Gas Company Public Works Bus System Telephone Company Power Company Water Dept. GIS Coordinating Unit E911 Planning Dept. Elections Assessment Dept. Data Once the approach to implementation has been decided, data issues need to be addressed. Data maintenance and sharing agreements among partners need to be created unless a single department is implementing the system. Database standards need to be agreed upon. Standards should include the following: naming and definition conventions (so that each named type of road, for instance, means only that type of road and all road names are entered in the same format)

11 Geographic Information Systems 11 mapping standards (coordinate system, scale, and symbols used to represent objects, line colors and widths, etc.) data documentation (information about the data such as source, coordinate system, scale, extent, and date of compilation) access privileges (who gets to do what with the data, software, and hardware) liability for inaccurate data quality assurance (who is responsible for data updates and accuracy checks and how often they occur) data backup and recovery procedures Policies created by the municipality based on database standards that have been agreed to and developed with all users of the system will streamline later steps in the implementation process. Before data are collected, a data model and database design should be decided upon. Users needs and expectations should be clearly defined at this stage. Database design affects how data should be collected and what kinds of analysis can be performed. It can also affect the software and hardware used. What kind of data are collected and how they are collected will depend on the preceding steps. As mentioned earlier, a basic set of data layers is available at no cost from state and federal sources. The Georgia GIS Data Clearinghouse makes Georgia data available over the Internet. County and municipal boundaries, roads, hydrology, elevation, and other data are provided by the U.S. Geological Survey, the U.S. Bureau of the Census, the Georgia Department of Transportation, and the Georgia Department of Natural Resources, among others. Other data will have to be acquired by manually digitizing or scanning paper maps or by using GPS data or aerial photography. The method used will depend on the types of data available, the equipment and personnel available, the accuracy required, and the cost. Different applications of GIS technology require different levels of accuracy. Engineering applications, such as utility or infrastructure management, generally require more accurate data than do planning applications. Regardless of the approach pursued in GIS implementation, an experienced consultant is generally required because of the highly technical nature of a GIS project. In addition, a GIS manager position should be established to ensure that the system continues to meet the evolving needs of the municipality.

12 12 Geographic Information Systems Available Resources The Regional Commissions (RCs) provide GIS services to member local governments, especially for comprehensive planning. Georgia colleges and universities provide GIS education. Some provide GIS services, including implementation planning and database development. Information Technology Outreach Services ( uga.edu/itos) is a University of Georgia unit that assists local governments with GIS technology (i.e., data development; training on the use, maintenance, and integration of GIS data with existing databases; and system implementation). The Urban and Regional Information Systems Association (URISA) is an organization of professionals using information technology and spatial information in planning, public works, and other governmental areas. URISA provides educational and other resources. NOTES 1. LIDAR is a remote sensing technology. Pulses of light are emitted from a laser source, and high-speed counters record the time it takes for the light signal to bounce off a surface and return to its source location. These recorded data can be used to model changes in elevation along the earth s surface and for a number of topography-related applications. 2. John O Looney, Beyond Maps (Redlands, CA: ESRI Press, 2000), Official Code of Georgia Annotated (O.C.G.A.)