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Types and Methods

The hydrographic survey is intended to investigate water depths, coastline configuration, rock locations and heights, and submarine geology.
The survey results are recorded in nautical charts and every waterway related publication, for the purpose of the use in the safety of navigation, port construction, and marine development.

Types of the Hydrographic Survey

  • Harbor survey This survey is intended for the safe navigation of vessels near ports and their surroundings.
  • Passage survey This survey is intended for safe navigation in main sea lanes.
  • Coastal survey This survey is intended for safe navigation and gaining knowledge about the bottom topography, sea-bottom sediments, and more in offshore waters.
  • Survey for correction The survey for correction (general hydrographic survey) is designed to measure water depths, coastlines, and geological features after dredging, artificial fish-reef installation, and such, and change waterway related publications such as nautical charts accordingly.

Methods of the hydrographic survey

DGPS

Hydrographic survey flow chart

  • Planning
    • Area and accumulation
    • Triangular net
    • Sounding line interval
    • Tidal observation
    • Waterway Service Act
    • Enforcement ordinance of the same Act
    • Enforcement Rule of the same Act
    • Regulation on hydrographic surveys
    • standard of the same regulations
  • Exploration
  • Formation of surveying team
    • Vessels
    • Personnel and equipment
  • Location survey
    • Surveying origins
    • Leveling
    • Coastline survey
    • Tidal observation
    • bathymetric surveying
    • Data edition
  • Survey drawing
  • Analysis and Summary
  • Result report

Changes in the hydrographic survey

  • Control point bathymetric surveying The control point surveying has been used to measure water depths in random points of coastal waters in Korea with the use of lead since the late 1800s when it was initiated for the purpose of defense against Japanese continental attack.
DGPS
  • Path based bathymetric surveying (single beam surveying) This surveying is conducted by a research vessel which navigates along defined paths at regular intervals and continuously records water depth on recording paper by means of the echo sounder.
DGPS
  • Sextant based positioning Between 1957 and 1978, positions at sea were determined by measuring two included angles among three targets with the use of a sextant.
DGPS
  • Sextant based positioning Between 1957 and 1978, positions at sea were determined by measuring two included angles among three targets with the use of a sextant.
DGPS
  • Trisponder based positioning (Trisponder) This method is to continuously measure distances by radio ranges between master and remote stations so as to determine the position, with two remote stations situated on land and one master station located in the sea within the effective range of microwave. Also, the orthocenter of a vessel is determined by means of the range-range manner.
  • Differential global positioning system(DGPS) This is designed to determine the location of a vessel by installing DGPS stations on land and correcting GPS coordinates received from the master station of a vessel.
DGPS