hydrography

hydrography
hydrographer, n.hydrographic /huy'dreuh graf"ik/, hydrographical, adj.hydrographically, adv.
/huy drog"reuh fee/, n.
1. the science of the measurement, description, and mapping of the surface waters of the earth, with special reference to their use for navigation.
2. those parts of a map, collectively, that represent surface waters.
[1550-60; HYDRO-1 + -GRAPHY]

* * *

      the art and science of compiling and producing charts, or maps, of water-covered areas of the Earth's surface. A brief treatment of hydrography follows. For full treatment, see map and surveying: Hydrography (surveying).

      The terms hydrography and hydrographer are based on an analogy with geography and geographer and date from the mid-16th century. Hydrography ordinarily denotes only the study of ocean depths and of the directions and intensities of ocean currents; other facets—such as temperature profiles or mineral content—are covered by the sciences of hydrology and oceanography.

      The British navy appointed its first hydrographer in 1795; and the United States established a naval observatory and hydrographical office in 1854. Since then many maritime nations have established hydrographic offices to furnish mariners with nautical charts and other publications necessary for navigation of their territorial waters and the oceans of the world. Hydrographic survey information is exchanged through the International Hydrographic Organization, chartered in 1970 under the auspices of the United Nations.

      The earliest navigators sailed from headland to headland by always keeping the coastline within sight. Navigators did not require charts until the advent of the magnetic compass in 1187 made it possible to proceed directly from one port to another across open water. Early charts were hand-drawn and very expensive. They were based entirely on magnetic directions and on map projections that assumed a degree of longitude equal to a degree of latitude. The assumption was not significant in the Mediterranean, but it caused serious distortions in maps drawn of areas at higher latitudes.

      Interest in the charting of the oceans away from seacoasts developed in the second half of the 19th century. A feature of marine science since the 1950s has been increasingly detailed bathymetric (water-depth measurement) surveys of selected portions of the seafloor.

      A hydrographic survey consists of two operations: determining the horizontal coordinates of points on the surface of the body of water (position fixing) and determining the water's depth at those points.

      The scale of a hydrographic chart expresses the relationship between a given distance on the chart and the actual distance it represents on the Earth's surface. Hydrographic charts are constructed on widely different scales; they range from ocean sailing charts drawn to a small scale of 1:5,000,000 (where 1 inch on the map represents 79 miles; or 1 cm = 50 km) to harbour charts, which are drawn to a scale of 1:50,000 (1 inch to 0.8 mile) or larger. Virtually all navigational charts, except for those made of the polar regions, represent the Earth's surface by the ordinary Mercator projection.

* * *


Universalium. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Hydrography — focuses on the measurement of physical characteristics of waters and marginal land. In the generalized usage , hydrography pertains to measurement and description of any waters. With that usage oceanography and limnology are subsets of… …   Wikipedia

  • Hydrography — Hy*drog ra*phy, n. [Hydro , 1 + graphy: cf. F. hydrographie.] 1. The art of measuring and describing the sea, lakes, rivers, and other waters, with their phenomena. [1913 Webster] 2. That branch of surveying which embraces the determination of… …   The Collaborative International Dictionary of English

  • hydrography — 1550s, from HYDRO (Cf. hydro ) + GRAPHY (Cf. graphy). Related: Hydrographic …   Etymology dictionary

  • hydrography — ► NOUN ▪ the science of surveying and charting bodies of water. DERIVATIVES hydrographer noun hydrographic adjective …   English terms dictionary

  • hydrography — [hī dräg′rə fē] n. [Fr hydrographie: see HYDRO & GRAPHY] 1. the study, description, and mapping of oceans, lakes, and rivers, esp. with reference to their navigational and commercial uses 2. the oceans, lakes, rivers, etc. of a region, esp. as… …   English World dictionary

  • hydrography — hidrografija statusas T sritis Gynyba apibrėžtis Mokslas, apimantis vandenynų, jūrų, ežerų, upių ir jų pakrančių matavimus ir jų fizinių ypatybių aprašymus, iš dalies siejant tai su jų naudojimu navigacijos reikmėms. atitikmenys: angl.… …   NATO terminų aiškinamasis žodynas

  • Hydrography of the San Francisco Bay Area — The Hydrography of the San Francisco Bay Area is a complex network of watersheds, marshes, rivers, creeks, reservoirs, and bays predominantly draining into the San Francisco Bay and Pacific Ocean.BaysThe largest bodies of water in the Bay Area… …   Wikipedia

  • hydrography engineer — hidrografijos inžinierius statusas T sritis profesijos apibrėžtis Inžinierius, kuris specializuojasi vandens tekėjimo, jo garavimo, nuosėdų susidarymo ir kitų susijusių reiškinių tyrimo ir analizės srityje. atitikmenys: angl. hydrographer;… …   Inžinieriai, technikai ir technologai. Trikalbis aiškinamasis žodynėlis

  • hydrography — The science which deals with the measurements and description of the physical features of the oceans, seas, lakes, rivers, and their adjoining coastal areas, with particular reference to their use for navigational purposes …   Military dictionary

  • hydrography — noun see hydrographic …   New Collegiate Dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”