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of public land net and boundaries. During fiscal year 1982, 5,250 digital line graphs were added to the data base bringing the total to over 14,800. Toward the end of fiscal year 1982, production of drainage and transportation digital line graphs increased. Those categories are expected to reach a much higher production level during fiscal year 1983. Also, during fiscal year 1982, the U.S. Geological Survey initiated a project to integrate the digital technology with revision processes so that the digital line graphs will be the primary base for revision mapping by the end of the decade.

Information Services

The Geological Survey disseminates much of the Nation's earth science information through its Public Inquiries Offices, National Cartographic Information Centers, and Earth Resources Observation Systems Data Center. This information comes in many forms from maps and booklets to scientific and technical reports to machine-readable data tapes.

The value of any product cannot be accurately determined until the public knows its availability and application to their particular needs and has used it. Market research techniques are being used to identify the many different user publics. A prime example is the market study of the digital spatial data industry, which was created from the merging of the cartographic and computer sciences. This market study will help to answer questions about the best way to disseminate this new type of information: Who are the users? what are their needs? how can the Survey best serve them? Many of the potential users are other Federal and State agencies.

State map indexes portray available 7.5-minute topographic map coverage. The current single-sheet index shows only a few selected map series. A new booklet format will show the entire range of available map series from the standard topographic quadrangle to the ecological inventories of the coastlines, cooperative Federal products, and special maps prepared for particular needs. Other indexes reflecting Survey special-product availability also help to expand the availability of Survey cartographic products to the public.

Research, Investigations, and Development

Raster-Formatted Digital Data

Applications research and software and techniques development are being conducted to address raster-formatted digital data. Raster-formatted data result from scanning a map area (similar to a television raster) as opposed to vector-formatted data which result from tracing individual lines on a map. These efforts center on the capabilities of the Scitex RESPONSE 250 map scanning, editing, and plotting system. Among 1982 achievements with the Scitex system were:

Q Map Reproduction.—Reproduction of a 1931 edition of a Survey map demonstrated the application of the Scitex for map reproduction. The only available copy of the map was a paper copy that showed its age through fold marks, age stains, and other signs of use. The original color separates were hand engraved on copper plates that are no longer usable for reprint purposes. The paper copy was scanned, and, using the editing functions of the Scitex electronic design console, the age stains, fold lines, and other blemishes were erased from the digital copy. Lines and symbols were retouched and repaired, and the map was rescaled to more modern dimensions. The laser printer was then used to generate reproduction-quality color separates for printing. The entire process reduced to a few hours a task that previously would have required months of manual labor.

' Shaded-Relief Graphics. — Digital elevation data are used to produce graphics representing topographic relief, based on slope aspect and Sun elevation and azimuth. The elevation data are coded to represent colors or shades of gray and the laser plotter is used to produce a film transparency that can be combined with other map separates to print a shaded-relief map of the terrain. Before these procedures were developed, shaded-relief graphics could only be prepared manually by personnel having special artistic skills.

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' Open- Window Graphics-Thematic maps often contain thousands of areas. Manually etching and peeling an openwindow color separate for just one classification is a labor-intensive and time-consuming task. Because a large quantity of the data exist in a digital data base, they can be retrieved and entered into the Scitex. The openwindow graphics produced by the laser plotter can then be combined with other map separates to produce a particular map.

' Production of Digital Line Graph Data. — Another important application of the Scitex is the production of digital line graph data. Map separates of contours are scanned and entered into the system for editing and conversion from a raster to a vector format. This is considerably more economical than previous methods that required manual tracing of the contours.

Satellite Surveying System

To take advantage of rapid development in Earth satellite technology, the Survey teamed with the Defense Mapping Agency and the National Geodetic Survey for development of geodetic applications of the NAVSTAR Global Positioning System. It is a worldwide satellite navigation and positioning system under development by the Department of Defense. The system is scheduled to replace the TRANSIT satellite navigation system, now maintained by the U.S. Navy, by 1986 or 1988. Use of the Global Positioning System satellite promises to provide the capability of attaining geodetic posi

tional data with much less effort and in less time than is required for current land based techniques.

The results of this activity have led to a contract awarded to the University of Texas, Applied Research Laboratory, to develop an Advanced Geodetic Receiver which will track four satellites simultaneously and will be capable of achieving accuracies to less than 3 feet.

Mapping of Irrigated Cropland with Landsat Digital Data

Landsat digital data can be used to indirectly estimate water withdrawal from irrigated cropland acreage. The High Plains aquifer, covering parts of eight States, supplies water for one-quarter of the Nation's irrigated agriculture. That supply of water is being depleted rapidly with little natural recharge. A computerized hydrologic model which will assist in evaluating effects of future ground-water pumpage is being constructed by staff members of the Survey’s High Plains Regional Aquifer Systems Analysis Project.

The key parameter is water pumpage, which is estimated from knowing the amount of land that is irrigated and how much water is used to irrigate an average acre. Landsat digital data were used to map irrigated cropland.

Land Cover of the Arctic National Wildlife Refuge Coastal Area

A land cover map of the Arctic National Wildlife Refuge coastal plain in northern Alaska was produced for an environmental

impact statement regarding proposed oil and gas exploration that was being prepared with Geological Survey support by the U.S. Fish and Wildlife Service. Three Landsat scenes were selected for analysis using knowledge of sites mapped in the field along with computer clustering techniques to establish spectral classes for the land classification. Results were validated with field reconnaissance notes and a description of vegetation associated with each category was compiled.

This unique thematic map depicts 12 land cover classes on a topographic base. Area tabulations of each class by public land survey township are also included, a distinct advantage of computer classification techniques.

Automated Names Processing Research

The processing of geographic names constitutes a significant portion of the mapmaking process. Now that geographic names are available in digital form in the Geographic Names Information System and output devices are available that automatically generate high-quality type in the correct position, the process of placing geographic names on maps can be automated. The names are selected and positioned on a proof copy of the map manuscript. The type is then generated and placed on the final manuscript automatically.

The members of one research team are investigating the use of the computercontrolled digital data editing system to prepare map lettering plates where the type in both the map border and the map interior is rapidly and accurately positioned using a

video screen. In most instances, the type style and size are automatically selected for the operator, thus eliminating many errors that occur in conventional type placement.

National Gazetteer Series

The Survey has reinstated the gazetteer program and is publishing the National Gazetteer of the United States of America on a State-by-State basis, with New Jersey as the first completed State. All volumes of the gazetteer will be published as parts of the Survey’s Professional Paper 1200. Each entry will contain the official name of the geographic feature (spelling and form), the feature class (kind of place and feature named), the official status of the name, the county in which the feature is located, the geographic coordinates (with sources and mouths of rivers, streams, canyons, and valleys identified), the elevation of place or feature, and the name of the Survey topographic map or the number of the National Ocean Survey chart on which the feature is found.

Aerial Profiling of Terrain System

The Aerial Profiling of Terrain System, under development since 1974, is a precision airborne surveying system capable of measuring elevation profiles across various types of terrain from a relatively light aircraft at flight heights up to 3,000 feet above the ground. A laser profiler measures the distance from the aircraft to the terrain, and an inertial measuring unit and a laser tracker provide the aircraft position by measuring the distance to ground-based reflectors.

Geologic and Mineral Resource Surveys and Mapping

Mission and Outlook

During fiscal year 1982, the Geologic Division conducted programs to assess energy and mineral resources onshore and offshore, to identify and investigate geologic hazards, and to evaluate the Nation's geologic framework, the geologic processes that have shaped it, and their relationship to long-term climatic changes. The mission of the Division was essentially unchanged from that of previous years, with the exception of the departmental decision on January 19, 1982, to transfer all direct suppport functions of the Outer Continental Shelf Leasing Program to the newly created Minerals Management Service. Although the Department's action to strengthen the Outer Continental Shelf Leasing Program resulted in a loss to the Geologic Division of mission responsibilities, the action simultaneously clarified and strengthened the Division's responsibilities in basic earth science research.

Fiscal year 1982 was a year of change as well as accomplishment in the Geologic Division with several implications for the future. In addition to its traditional basic research and fact finding role, the Division will be increasingly called upon to emphasize its data dissemination and public information activities in support of such diverse mission objectives as land use planning, energy and mineral development, and geologic hazard mitigation. These increased responsibilities will require closer collaboration with agencies at the Federal, State, and local levels.

The articles in this section of the Yearbook describe some of the most significant accomplishments of the Geologic Division during fiscal year 1982. We believe that these articles, while representing only a select few of the activities of the Division, show how geologic research simultaneously opens new avenues in geoscience and provides the basic information to serve missions central to the national welfare.

Major Programs

The Geologic Division budget is presented to Congress under five major program

headings. A discussion of accomplishments under these sub activities during this last fiscal year follows:

Geologic Hazards Surveys

In addition to the work described in the articles regarding the Los Angeles, California, urban areas earthquake hazards assessment and the studies of subsidence near Houston, Texas, the Geologic Division continued to monitor and assess the potential for the imminent renewal of volcanic activity at Mount St. Helens, Washington, and Mammoth Lakes-Long Valley, California. Because of the threat to human life and the major economic impacts that would be associated with an earthquake, volcanic eruption, or major landslide, the Geologic Division recognizes its Hazards Program responsibilities as among the most challenging that it must address in the next several years. The Division will continue to emphasize increasing its capability to identify and understand geologic hazards while also providing products that will enable Federal, State, and local governments to make informed land use, zoning, and engineering design decisions that will enhance the Nation's capability to avoid and mitigate these potential hazards.

Land Resource Surveys

During fiscal year 1982, the Geologic Framework Program continued to provide new insights into the fundamental geologic structure of the United States. The publication of numerous maps and reports resulting from these studies translate directly into new understanding of geologic hazards and the Nation's energy and mineral resources. A following article on the evolution of the Pacific Coast is illustrative of the nature of the research provided by the Geologic Framework Program. In addition, observations from the 11 geomagnetic observatories produced data that supported the preparation of topographic, nautical, and aeronautical maps and charts. The Geologic

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