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This method revolutionized hydrographic surveying, as it allowed a quicker, less laborious, and far more complete survey of an area than did the use of lead lines and sounding poles. From a navigational safety point of view, a wire-drag survey would not miss a hazard to navigation that projected above the drag wire depth.
Bathymeric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
Bathymeric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward. [27]
Bathymetric surveys are traditionally done from the surface, by measuring depth (soundings) at measured positions along transect lines and later plotting the data onto a bathymetric chart, on which lines of constant depth (isobaths) may be drawn by interpolation of soundings.
Depth contour lines show the shape of underwater relief. Coloured areas of the sea emphasise shallow water and dangerous underwater obstructions. Depths are measured from the chart datum, which is related to the local sea level. The chart datum varies according to the standard used by each national Hydrographic Office.
The International Hydrographic Organisation IHO operates a project team on Satellite-derived bathymetry supporting the Hydrographic Surveys Working Group. It has published the B-13 IHO publication an Guidelines for Satellite-derived bathymetry which provides more detailed information on each method.
Table of geography, hydrography, and navigation, from a 1728 Cyclopaedia.. Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary purpose of safety of navigation and in support of all other marine activities ...
The GEBCO chart series was initiated in 1903 by an international group of geographers and oceanographers, under the leadership of Prince Albert I of Monaco.At that time there was an explosion of interest in the study of the natural world and this group recognized the importance of a set of maps describing the shape of the ocean floor.