Hydrography 164974 221642569 2008-06-25T12:40:00Z JAnDbot 1725149 robot Removing: [[zh:水文地理學]] [[Image:Table_of_Geography_and_Hydrography,_Cyclopaedia,_Volume_1.jpg|thumb|right|200px|Table of geography, hydrography, and navigation, from the 1728 ''[[Cyclopaedia]]''.]] '''Hydrography''' focuses on the measurement of physical characteristics of [[water]]s 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 [[vessel]]s. == 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 [[hydrocarbon]]s. Hydrographical measurements will include the [[tides | tidal]], [[Ocean currents | current]] and [[wave]] information of physical oceanography. They will include [[seafloor | bottom]] measurements, with particular emphasis on those marine geographical features that pose a hazard to navigation such as rocks, [[shoal]]s, [[reef]]s 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 [[hill]]s, [[mountain]]s and even lights and [[tower]]s 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 [[depth]]s and ignore the actual submarine [[topography]] that will be portrayed on [[Bathymetric chart|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 [[geomorphology | geomorphologic]] descriptive requirements of the latter. As just one important example the [[Echo sounding | 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 [[stream]]s will include information on the stream bed, [[flow]]s, [[water quality]] and surrounding land. [[drainage basin | 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 [[Commerce|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 office]]s. 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 == * [[Bathymetric chart]] * [[Cartography]] * [[Coastal geography]] * [[Drought]] * [[Evapotranspiration]] * [[Flood]] * [[Hydrology]] * [[Hydrologic cycle]] * [[Hydrometeorology]] * [[Hydrometry]] * [[Trasvasement]] * [[Virtual water]] == External links == * [http://www.ukho.gov.uk United Kingdom Hydrographic Office] - an executive agency of the UK's Ministry of Defence. * [http://www.hydrographicsociety.org International Federation of Hydrographic Societies (formerly The Hydrographic Society)] * [http://www.uky.edu/KGS/gis/kydrain.htm Hydrography of Kentucky] * [http://sun1.giac.montana.edu/gyadc/metadata/grtehydr.html Hydrography of Grand Teton National Park] and surrounding area * [http://www.regione.abruzzo.it/turismo/en/territorio/hydrography.htm The hydrography of an Italian region] * [http://www.dhyg.de/joomla/index.php German Hydrographic Society] * [http://chartmaker.ncd.noaa.gov/hsd/hydrog.htm NOAA Hydrography and coastal surveys] * [http://nhd.usgs.gov/ USGS National hydrographical dataset] * [http://www.hcu-hamburg.de/geomatik/department/department.htm HafenCity Universität Hamburg Department Geomatik] * [http://www.hydrobharat.nic.in Indian Hydrography * [http://www.ccom.unh.edu The Center For Coastal and Ocean Mapping - Joint Hydrographic Center] * [http://www.charts.gc.ca Canadian Hydrographic Service] {{Physical geography topics}} [[Category:Hydrography| ]] [[Category:Oceanography|Hydrography]] [[Category:Hydrology]] [[Category:Physical geography]] [[bs:Hidrografija]] [[cs:Hydrografie]] [[de:Hydrographie]] [[et:Hüdrograafia]] [[es:Hidrografía]] [[fa:آب‌نگاری]] [[fr:Hydrographie]] [[gl:Hidrografía]] [[hr:Hidrografija]] [[it:Idrografia]] [[he:הידרוגרפיה]] [[lb:Hydrographie]] [[ms:Hidrografi]] [[nl:Hydrografie]] [[pl:Hydrografia]] [[pt:Hidrografia]] [[ru:Гидрография]] [[sk:Hydrogeografia]] [[sh:Hidrografija]] [[sv:Hydrografi]] [[tr:Hidrografi]]