National Academies Press: OpenBook

Current Problems in Geodesy (1987)

Chapter: OBJECTIVES OF GEODESY

« Previous: HISTORY
Suggested Citation:"OBJECTIVES OF GEODESY." National Research Council. 1987. Current Problems in Geodesy. Washington, DC: The National Academies Press. doi: 10.17226/19180.
×
Page 2
Suggested Citation:"OBJECTIVES OF GEODESY." National Research Council. 1987. Current Problems in Geodesy. Washington, DC: The National Academies Press. doi: 10.17226/19180.
×
Page 3

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

HISTORY Recognizing that geodesy provides valuable ideas and data and makes fundamental contributions to the earth sciences, the then Division of Earth Sciences (now the Board on Earth Sciences) of the National Research Council proposed the establishment of a Committee on Geodesy in 1975. The Committee began operations in early 1976. Its objectives were: (1) to review the state of scientific and technological advances in modern geodesy and related fields and to determine when technique and methodology transfer is practicable; (2) to review the planning for space-borne instrumentation pertinent to geodesy during the 1980s and to make appropriate recommendations; (3) to review the need for geodetic control for the oceans and to recommend any action needed to implement such control; (4) to review educational opportunities in geodesy and surveying and to recommend needed actions for their improvement; (5) to review the status of current work in plane surveying and mapping and to recommend action needed to improve their significance with respect to science, technology, and society; (6) to review the status of current work on traditional geodesy and to recommend action to complement the work; and (7) to provide a Visiting Scientist Program in Geodesy. These objectives have been pursued through a series of published reports (Appendix I), letter reports (Appendix II), and Senior Scientist reports (Appendix III). Classically, geodesy was considered a branch of applied mathematics that determined by observations and measurement the exact positions of points and the shapes and areas of large portions of the earth's surface, the shape and size of the earth, and variations of terrestrial gravity. Today, geodesy is considered both an applied and a basic science, a subdivision of both geophysics and engineering with applications to the oceans, moon and planets, and the solid earth. OBJECTIVES OF GEODESY The major goals of this science may be summarized as follows: (1) Establishment and maintenance of national and global three-dimensional geodetic control networks, recognizing the time variant aspects of these networks.

Geodetic networks provide the control essential for mapping and charting programs. The ultimate goal is a global system providing three-dimensional coordinates for national and international mapping and charting programs with confidence that there will be no inconsistencies between networks produced by individual countries. Closely related to these programs are the positions of boundary points, ranging from private property to international boundaries, for which geodetic data must be of the highest accuracy and reliability. These geodetic data should provide the basis for the definition of tracts of land, land parcel identification, tax mapping, and land use management. For the space program, these data provide the positions of tracking stations and rocket launch sites. Applications of these data are also essential to engineering activities such as highway construction, pipelines, transmission lines, and dams. These activities fall into the category of engineering applications of geodesy. (2) Measurement and representation of such geodynamic phenomena as polar notion, earth tides, and crustal motion. The dynamic behavior of the earth introduces another dimension to geodetic measurements: time. Tectonically significant rates are on the order of millimeters/year; to monitor these motions is a real geodetic challenge. The establishment and maintenance of a reference frame within which the time variant phenomena can be represented is one of the important geodetic goals. The task of maintaining accurate up-to-date control networks is made difficult by changes occurring in the earth's crust, either natural or induced by man. Ground water extraction has induced subsidence and some flooding along the sea coast, along the shores of the Great Lakes, and in the upper Mississippi Valley. Periodic releveling or use of the Global Positioning System (GPS) may be used to monitor these changes. Where large quantities of water and/or petroleum are extracted, there is generally an associated pattern of horizontal displacement. In regions of seismic activity, the rate of crustal deformation is sufficient to justify a program of periodic resurveys. The differential motions detected by these surveys may provide essential information for determining stress patterns and rates of strain accumulation. In the event of an earthquake with a surface fracture, resurveys are needed to measure the displacements and to restore the network for its fundamental use. These activities fall into the category of geophysical applications of geodesy. (3) Determination of the gravity field of the earth, including temporal variations. Over large portions of the solid earth and the sea surface, the gravity field has been mapped but not in detail sufficient to meet the needs of oceanographers and geophysicists. A geometrical

Next: AREAS OF STUDY »
Current Problems in Geodesy Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF
  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!