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Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia.
Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. Cyclopaedia or A Universal Dictionary of Arts and Sciences ( folio, 2 vols

Hydrography focuses on the measurement of physical characteristics of waters and marginal land. Water is a common Chemical substance that is essential for the survival of all known forms of Life. In the generalized usage, "hydrography" pertains to measurement and description of any waters. With that usage oceanography and limnology are subsets of hydrography. Oceanography (from the greek words Ωκεανός meaning Ocean and γράφω meaning to write also called oceanology or Limnology (from Greek Λίμνη limne, "lake" and λόγος logos, "knowledge" is the division of Hydrology that studies inland In specialized usage the term applies to those measurements and descriptions of navigable waters necessary for safe navigation of vessels. A body of water such as a River, Canal or Lake, is navigable if it is deep wide and slow enough for a vessel to pass and there are no obstructions like Navigation is the process of reading and controlling the movement of a craft or vehicle from one place to another

Contents

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. In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon.

Hydrographical measurements will include the tidal, current and wave information of physical oceanography. Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood An ocean current is continuous directed movement of Ocean water. A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. 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. "Ocean Floor" redirects here For the 2001 song by Audio Adrenaline, see Lift (Audio Adrenaline album. A shoal or sandbar (also called sandbank) is a somewhat Linear Landform within or extending into a body of Water, In nautical terminology a reef is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less at low water A ship /ʃɪp/ is a large vessel that floats on water Ships are generally distinguished from Boats based on size 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. Hydrographic survey in its strictest sense is the process of gathering information about navigable waters for the purposes of safe navigation of vessels A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak Towers are tall human-made Structures that are always taller than they are wide usually by a significant Margin.

Hydrography, partly for reasons of safety, tends to be more traditional in outlook and has conventions that are not entirely "scientific" in some views. Safety is the state of being "safe" (from French sauf) the condition of being protected against physical social spiritual financial political 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. Topography ( topo-, "place" and graphia, "writing" is the study of Earth 's Surface features or those of Planets A bathymetric chart is the submerged equivalent of an above-water Topographic map. 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. Geomorphology (from Greek: γη ge, "earth" μορφή morfé, "form" and λόγος Logos, "knowledge" 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. Echo sounding is the technique of using Sound pulses directed from the surface or from a submarine vertically down to measure the distance to the bottom by means of sound waves


Hydrography of streams will include information on the stream bed, flows, water quality and surrounding land. A stream is a body of Water with a current, confined within a bed and stream-banks Water quality is the physical chemical and biological characteristics of Water in relationship to a set of standards Basin or Interior Hydrography pays special attention to rivers and potable water. A drainage basin is an extent of Land where Water from Rain or Snow melt drains downhill into a body of water such as a River, "Riverine" redirects here For the use of that term in Maritime geography, see there Water of sufficient quality to serve as drinking water is termed potable water whether it is used for drinking or not

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. Commerce is a division of trade or production which deals with the exchange of goods and services from producer to final consumer A military is an Organization authorized by its Nation to use force usually including use of Weapons in defending its Country (or by attacking 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. James Whistler may refer to James Abbott McNeill Whistler, 19th-century American-born British-based painter known for the painting colloquially known as 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. A harbor or harbour (see spelling differences) or haven, is a place where ships may shelter from the Weather or are stored

Organisations

Hydrographic services in most countries are carried out by specialised hydrographic offices. A hydrographic office is an organization which is devoted to acquiring and publishing hydrographic information The international coordination of hydrographic efforts lies with the International Hydrographic Organization. The International Hydrographic Organization (IHO was originally established in 1921 as the International Hydrographic Bureau (IHB

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. The United Kingdom Hydrographic Office (or UKHO) is an organisation within the UK government responsible for providing Navigational and other hydrographic

See also

External links


Dictionary

hydrography

-noun

  1. (nautical) the scientific measurement and description of the physical features and conditions of navigable waters and the shoreline
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