| Abstract from DBPedia | Bathymetry (/bəˈθɪmətri/; from Ancient Greek βαθύς (bathús) 'deep', and μέτρον (métron) 'measure') is the study of underwater depth of ocean floors (seabed topography), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. Bathymetric (or hydrographic) charts are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines (called depth contours or isobaths) and selected depths (soundings), and typically also provide surface navigational information. Bathymetric maps (a more general term where navigational safety is not a concern) may also use a Digital Terrain Model and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is sometimes combined with topography data to yield a global relief model. Paleobathymetry is the study of past underwater depths.水深測量（すいしんそくりょう）とは、水深を測量すること。海の水深については潮汐により変化するため、一般には最低水面（略最低低潮面）から海底までの長さをいう。 (Source: http://dbpedia.org/resource/Bathymetry) |
