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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission 5 NAUTICAL INFORMATIONASA COMPONENTOFA MARINE GEOGRAPHIC INFORMATION SYSTEM The National Oceanic and Atmospheric Administration (NOAA) is in the process of producing a digital data base of the information appearing on its current nautical charts. When completed, this data base will simplify and speed nautical chart updating and production. This data base can also serve effectively as a key component of a broader marine geographic information system (GIS) with the potential of providing a wide range of coastal and marine environmental information products. As a result of the ongoing information science and technology revolution, GIS and related technologies, such as Global Positioning Systems and remote sensing, have emerged as premier tools to organize, analyze, and display coastal data for uses other than the traditional safe navigation of marine commerce. Yet both the traditional and the new users can be satisfied by the same data base. Information on the NOAA nautical charts serves well as the base layer for coastal zone and marine resource GIS applications, in the same way as a U.S. Geological Survey (USGS) quadrangle map is often used as the base map for land resource GIS applications. Critical nautical chart features for these purposes include shoreline, culturally and navigationally important landmarks, critical soundings and depth curves, shoals, wrecks, obstructions, boundaries of regulated areas, and fixed and floating aids to navigation. When the charts are digitized, these features become available for sophisticated spatial queries in the GIS. When the charts are scanned into raster files they can be used as a visual backdrop to add value and relevance to the project-specific data under investigation. Together, the two map representations form a powerful data base for managing the coastal zone. The needs of local, state, and federal resource managers for digital data from nautical charts are significant and growing. Given that there are 30 coastal states, including those bordering the Great Lakes, and more than 450 coastal counties, the growing number of GIS installations under development by private and public agencies constitutes a significant demand for coastal data. If NOAA does not provide data products, these users must find other ways to obtain the necessary data, often in a variety of incompatible formats and at a significantly higher cost. If NOAA is able to address the needs of these nontraditional users of nautical data, unnecessary duplication of effort can be avoided and better resource management decisions can be made.
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission INFORMATION FOR COASTAL MANAGEMENT Dealing effectively with coastal environmental degradation and resolving future land-use conflicts will require an intelligent balance between many competing demands. Engineers, scientists, planners, managers, decisionmakers, and the public need timely access to understandable information to assist in making difficult choices (Williams et al., 1991). Coastal management issues such as habitat modeling, carrying capacity analysis, fisheries assessment, pollution monitoring, and emergency contingency planning (including oil spill response) require vast quantities of data to be assimilated. Given that most of the information pertaining to the marine environment has a spatial component, a GIS provides a means to aggregate and analyze the disparate data generated by public and private sources. Such systems are rapidly replacing the traditional cartographic techniques that have typified most coastal mapping and resource inventory projects and that are now being applied to coastal management efforts worldwide (Ricketts, 1992). Effective use of these increasingly sophisticated spatial analysis tools is, in turn, dependent on the availability of high-quality data bases that characterize the physical and cultural resources of the coastal zone. Data-base development costs can be orders of magnitude higher than the cost of software and hardware involved in developing a coastal GIS (Haddad and Michener, 1991). To build affordable data bases, organizations usually rely on automating the production of existing paper map series or integrating derivative digital products that are maintained by federal agencies. The ubiquitous USGS quadrangle (quad) map series provides a rich base map upon which many land-based GIS users center their data-base development efforts. Land-based features are emphasized on the quads; however, coasts are the dynamic junction of land and water. The topographic and hydrographic surveys of NOAA's National Ocean Service, as well as NOAA nautical charts, provide the only comprehensive U.S. data base that depicts marine features from the shoreline seaward with an acceptable level of accuracy. EXAMPLES OF GIS APPLICATIONS TO COASTAL RESOURCE MANAGEMENT Many GIS developers in the 30 coastal states are digitizing elements of the NOAA nautical charts, NOAA topographic and hydrographic surveys, and USGS quadrangles to form digital base maps. The following examples provide a small but representative sample of how NOAA chart information is used in conjunction with project-specific data to support coastal decisionmaking in several states. These examples illustrate the advantages of using GIS for coastal resource management; however, the availability of a fully attributed nautical information data base would have saved time and money in all these cases. The Coastal and Marine Assessment program at the Florida Marine Research Institute has invested considerable resources to convert NOAA nautical chart information to a format for use in a GIS. The Florida Marine Research Institute is mandated to manage, protect, and enhance Florida's marine resources. To accomplish this objective, it developed the Marine Resources Geographic Information System, which uses the latest in raster and vector technologies to synthesize a broad range of cultural and marine resource information. Many
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission of the most useful data bases in the Marine Geographic Information System are derivative products of NOAA nautical charts. These data bases have been used to support a variety of projects, including fisheries management, marine mammal research, oil spill response planning, site selection for testing of explosives, and diving operations in the Florida Keys. Appendix G provides some details of these examples. In response to the Exxon Valdez oil spill, the State of Alaska and federal agencies developed a uniform digital coastline to track oil impacts, manage cleanup activities, and conduct natural resource damage assessment studies. The Alyeska Pipeline Company has developed a graphical resource data base to assist in its response to future oil spills and help meet state and federal spill contingency planning requirements. The Alaska Department of Fish and Game utilizes the SEAPLOT nautical charting and navigation system on several of its vessels engaged in fisheries research. The U.S. Fish and Wildlife Service utilized a digital bathymetric contour map to aid in its assessment of injury to sea otters from the Exxon Valdez oil spill. Details of these projects are given in Appendix G. Louisiana has about 40 percent of the nation's coastal wetlands. They represent a renewable natural resource base that is valued at more than $1 billion annually and include 25 percent of the nation's fish harvest, its largest fur harvest, the highest concentration of waterfowl, and the country's largest recreational marine fishery. Recent studies indicate that coastal Louisiana has one of the world's most rapidly changing shorelines with retreat rates exceeding 20 meters per year in some areas. Wetland habitats protected by outer coast deposits are being replaced by open water at a rate of 65 square kilometers per year. Various agencies and universities in Louisiana are studying these ecosystems to better understand their origin and evolution and the impact of human activities on environmental response. As an example, personnel at the Center for Coastal, Energy and Environmental Resources at Louisiana State University are performing comprehensive studies of coastal change using repetitive NOAA shoreline position and bathymetric survey data. Further details are given in Appendix G. MEETING USER REQUIREMENTS It is useful for NOAA to look at the information on its nautical charts in terms of comprising several data bases and to establish a process for marketing them by theme or geographical area to GIS users from the NOAA digital nautical data base of the future. Several data themes on existing nautical charts could easily be made available as data bases ready for use in a GIS. Users will need to be made aware of the existence of NOAA digital data through technical presentations and a formal marketing program. The USGS has taken this approach with its popular Digital Line Graph files. These files reflect the cartographic information extracted from 1:100,000 and 1:24,000 map sheets for the United States. Digital Line Graph information can be easily exchanged and directly imported to a GIS because it is in a standard format. Experience with the Digital Line Graph files has shown that they are of very high quality, in both their cartographic information and their attribute data (Dangermond, 1990).
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission Many of the needs of nonnavigation users can be met with some additional design considerations at very little additional cost to NOAA. The fundamental data themes such as shoreline, bathymetry, and aids to navigation are already planned as elements of NOAA's digital nautical data base. Marine GIS users need the files to be designed and created as data bases, not just graphic layers. Older NOAA digital shoreline products contained the cartographic representation as graphics. This was adequate for reproducing the shoreline as drawn on the chart, but the shoreline recorded in the digital file was interrupted by other map features such as text labels, compass roses. Naturally, GIS users need the data to be free from errors. Older NOAA shoreline data products contain significant errors, such as wild points, missing data, and duplicate data. The quality control processes used to validate the data need to be clearly described, so that users will be assured that they can use the data immediately, without having to make an unexpected investment in data cleansing. Nontraditional users also need the data base to be complete. A data base that is completely populated for only some charts in a region or partially populated for some data features is much less useful. After implementing greater data accuracy and quality reporting, NOAA needs to be less cautious and more open with its data holdings. NOAA has many data sets that represent data in some stage of processing, which may not be suitable for navigation purposes but can be very useful for marine GIS purposes. Some marine GIS users need older data for time-series studies, as well as data displayed on the most recent charts. NOAA does not plan to digitize data that are not displayed on the most recent charts. Older data not in digital form could be digitized and stored in the digital nautical data base or made available in analog form to users who would return the results of their digitizing to NOAA. NOAA should participate in the spatial data clearinghouse efforts being coordinated by the Federal Geographic Data Committee and adopt standards that are compatible with the Federal Data Transfer Standard under development by this committee. BEYOND THE DIGITAL NAUTICAL DATA BASE There are additional needs of nontraditional users that go beyond the planned elements of NOAA's digital nautical data base. Some of these could be accommodated through a modest collaborative effort. For instance, a state or local agency might perform a detailed large-scale survey, producing more detailed shoreline or bathymetry data than are shown on any nautical chart. While these detailed data might not be necessary or even useful for the production of existing or planned nautical charts, such data could be a logical extension of the digital nautical data base and could be built on the spatial framework of nautical chart data. The digital nautical data base would serve as the vehicle for dissemination of these data to potential users. NOAA could bring data from other contributors into the digital nautical data base by assisting in the development of format and quality standards and by providing consulting services to potential data contributors. Cartographic consistency between map series is an important issue for builders of coastal zone GIS data bases. Since shoreline depictions on NOAA nautical charts and USGS quadrangle map products do not match, the GIS analyst is faced with a significant challenge
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission (Needham and Lanzer, 1993). While there are some cases when different maps portray the same shoreline differently for justifiable reasons (e.g., different tidal data), there are other cases in which the depictions simply reflect two different agencies drawing the shoreline with independent sources and methods. For instance, NOAA maps the shoreline at a scale of 1:40,000, while the USGS maps it at 1:24,000. NOAA and the USGS should develop ways to more closely coordinate their depictions. A priority should be placed on accuracy and currency of these depictions. This will require a greater emphasis on acquiring data from other sources (e.g., other agencies) and, where necessary, collecting new data. A digitized attributed shoreline should be a fundamental data theme that is jointly maintained by NOAA and the USGS and made available through the digital nautical data base (see Appendix H). For NOAA nautical chart data to have widespread utility, they need to be made available in a format that is appropriate for nautical charting, electronic charting systems, and GIS. In the future the format issue will be resolved if nautical chart information is produced by using the Spatial Data Transfer Standard (Federal Information Processing Standard 173). Users also need data elements that are similar to, but not exactly the same as, those in NOAA's planned data base. Among these are the shoreline drawn with respect to different tidal data (higher high water, lower low water, etc.) and bottom samples. Although these data elements are not in the nautical charting data base, they might be available from other NOAA programs. The shoreline shown on the nautical charts represents the line of contact between the land and a selected water elevation. At the present time, the shoreline on NOAA nautical charts approximates the mean high water line. In areas affected by tidal fluctuations, this line of contact is usually the mean high water line. In confined coastal waters of diminished tidal influence, the mean water-level line may be used. However, for charting purposes (i.e., safety of navigation and maritime boundary determination) the low water line is more critical. It would be valuable if both of these data elements could be supplied for use in a GIS. With respect to these nonnavigation users, NOAA needs to be less cautious and more open with its data holdings. NOAA has many data stores that represent data in some stage of processing. While unverified data are clearly not suitable for navigation purposes, they can be enormously useful for a marine GIS. When a new chart is produced, traditional users are notified through Notices to Mariners and other means. A similar service could be provided for the planned digital data holdings to be reported to the nonnavigation users. Most elements of the digital nautical data base are useful for environmental studies and coastal zone management; however, the following data elements have the highest priority for many nontraditional users: shoreline position (consistent with USGS), bathymetry (denser than on charts, especially near shore), aids to navigation, bottom types, managed areas (special areas), scanned and edge-matched master charts, and a digital coast pilot. Bringing together data from separate programs may be the biggest challenge. Agencies that use NOAA data for purposes other than navigation do not distinguish between the separate mandates of the various NOAA programs, such as the Nautical Charting Program and the Coastal Zone Management Program or programs established under the Oil
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission Pollution Act of 1990. Users expect that NOAA should facilitate its activities by making nautical chart data (and other data) readily available in a usable format. To meet these needs, NOAA would have to broaden its responsibilities beyond the mandates of the separate programs to include the needs of the coastal zone research and management community and other marine GIS users. Managers of the Coastal Zone Management Program and spill contingency plans could, in turn, facilitate marine GIS activities by supporting the transfer of their data to NOAA. Data from all NOAA programs could be managed through a well-designed digital nautical data base for general distribution to a variety of users. SUMMARY The digital nautical data base developed and maintained by NOAA as its core mission in nautical charting can also serve effectively as a key component of a broader marine GIS, providing a wide range of coastal and marine environmental information products to fulfill NOAA's mandate for marine environmental stewardship. NOAA has a clear statutory mandate and the expertise to be the lead agency for coordination and maintenance of such a master nautical data base. The format and content of NOAA data can be made amenable for use with a marine environmental GIS at very little additional cost to NOAA. To facilitate use of nautical chart information in a GIS, efforts should be made to adopt the Spatial Data Transfer Standard developed by the Federal Geographic Data Committee. NOAA and the USGS should seek a closer coordination between their depictions of the shoreline. This information would serve the nation's growing concerns about marine and coastal environmental quality and avoid duplication of effort by other public (federal and state) agencies. REFERENCES Dangermond, J. 1990. A review of digital data commonly available and some of the practical problems of entering them into a GIS. Pp. 222-232 in D. J. Peuquet and D. F. Marble (eds.), Introductory Readings in Geographic Information Systems. Taylor & Francis, Inc., Bristol, Pennsylvania. Haddad, K. D., and W. K. Michener. 1991. Design and implementation of a coastal resource geographic information system: administrative considerations. Pp. 1958-1967 in Proceedings of the Seventh Symposium on Coastal and Ocean Management/ASCE. Charleston, S.C. Needham, E. L., and E. L. Lanzer. 1993. The Puget Sound Geographic Information System: a tool for coordinated environmental management. Computers, Environment and Urban Systems 17:1-23.
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Charting a Course into the Digital Era: Guidance for NOAA's Nautical Charting Mission Ricketts, P. J. 1992. Current approaches in geographic information systems for coastal management. Marine Pollution Bulletin 25:82-87. Williams, S. J., K. Dodd, and G. K. Krafft. 1991. Coasts in Crisis. U.S. Geological Survey Circular 1075. U.S. Geological Survey, Washington, D.C.
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