AskDefine | Define hydrography

Dictionary Definition

hydrography n : the science of the measurement and description and mapping of the surface waters of the earth with special reference to navigation

User Contributed Dictionary

English

Noun

hydrography
  1. the scientific measurement and description of the physical features and conditions of navigable waters and the shoreline

Translations

Extensive Definition

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 hydrography. In specialized usage the term applies to those measurements and descriptions of navigable waters necessary for safe navigation of vessels.

Overview

Large scale hydrography is usually undertaken by national or international organizations that sponsor data collection through precise surveys and the publication of charts and descriptive material for navigational purposes. The science of oceanography is, in part, an outgrowth of classical hydrography. In many respects the data are interchangeable, but marine hydrographic data will be particularly directed toward marine navigation and safety of that navigation. Marine resource exploration and exploitation is a significant application of hydrography, principally focussed on the search for hydrocarbons.
Hydrographical measurements will include the tidal, current and wave information of physical oceanography. They will include bottom measurements, with particular emphasis on those marine geographical features that pose a hazard to navigation such as rocks, shoals, reefs and other features that obstruct ship passage. Unlike oceanography, hydrography will include shore features, natural and manmade, that aid in navigation. A hydrographic survey will therefore include accurate positions and representations of hills, mountains and even lights and towers that will aid in fixing a ship's position as well as the aspects of the sea and seabed.
Hydrography, partly for reasons of safety, tends to be more traditional in outlook and has conventions that are not entirely "scientific" in some views. For example, hydrographic charts will usually tend to over represent least depths and ignore the actual submarine topography that will be portrayed on bathymetric charts. The former are the mariner's tools to avoid accident. The latter are best representations of the actual seabed, as in a topographic map, for scientific and other purposes.
A hydrographic survey is quite different from a bathymetric survey in some important respects, particularly in a bias toward least depths, because of the safety requirements of the former and geomorphologic descriptive requirements of the latter. As just one important example the echosoundings will be conducted under settings biased toward least depths while in bathymetric surveys they will be set for best description of the submarine topographical features that may include sound velocity and slope corrections that are more accurate but eliminate the safety bias.
Hydrography of streams will include information on the stream bed, flows, water quality and surrounding land. Basin or Interior Hydrography pays special attention to rivers and potable water.

History

Hydrography's origin lies in the making of chart like drawings and notations made by individual mariners. These were usually the private property, even closely held secrets, of individuals who used them for commercial or military advantage. Eventually organizations, particularly navies, realized the collection of this individualized knowledge and distribution to their members gave an organizational advantage. The next step was to organize members to actively collect information. Thus were born dedicated hydrographic organizations for the collection, organization, publication and distribution of hydrography incorporated into charts and sailing directions.
An interesting historical relationship is that of James Whistler to hydrography. His artistic talents were applied to the sometimes beautiful shore profiles that appeared on charts during his work as a cartographer with both the civilian and naval U. S. hydrographic organizations. Those profiles on early charts were etchings designed to aid mariners in identifying their landfall and harbor approaches.

Organisations

Hydrographic services in most countries are carried out by specialised hydrographic offices. The international coordination of hydrographic efforts lies with the International Hydrographic Organization.
The United Kingdom Hydrographic Office is one of the oldest and most respected hydrography organisations in the world, supplying the widest range of charts covering the globe to other countries, allied military organisations and the public.

See also

hydrography in Bosnian: Hidrografija
hydrography in Czech: Hydrografie
hydrography in German: Hydrographie
hydrography in Estonian: Hüdrograafia
hydrography in Spanish: Hidrografía
hydrography in Persian: آب‌نگاری
hydrography in French: Hydrographie
hydrography in Galician: Hidrografía
hydrography in Croatian: Hidrografija
hydrography in Italian: Idrografia
hydrography in Hebrew: הידרוגרפיה
hydrography in Luxembourgish: Hydrographie
hydrography in Malay (macrolanguage): Hidrografi
hydrography in Dutch: Hydrografie
hydrography in Polish: Hydrografia
hydrography in Portuguese: Hidrografia
hydrography in Russian: Гидрография
hydrography in Slovak: Hydrogeografia
hydrography in Serbo-Croatian: Hidrografija
hydrography in Swedish: Hydrografi
hydrography in Turkish: Hidrografi
hydrography in Chinese: 水文地理學
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