hydrography

Information about hydrography

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Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia.


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.

Hydrographic 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 differs 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 maps done by geographers in by means 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.

See also

External links

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Sub-fields of Physical Geography
Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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Oceanography (from Ocean + Greek γράφειν = write), also called oceanology or marine science, is the branch of Earth Sciences that studies the Earth's oceans and seas.
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Limnology (from Greek: Λίμνη limne, "lake"; and λόγος, logos, "knowledge") is the study of inland waters (both fresh and saline), including their biological, physical, chemical, geological and hydrological aspects.
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A body of water, such as a river, canal or lake, is navigable if it is deep and wide enough for a vessel to pass and there are no obstructions, like rocks, trees and low bridges. Shallow rivers may be made navigable by the installation of locks that increase and regulate water depth.
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Navigation is the process of planning, recording, and controlling the movement of a craft or vehicle from one place to another.[1] The word navigate is derived from the Latin roots navis meaning "ship" and agere meaning "to move" or "to direct.
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wave is a mode of energy transfer from one place to another, often with little or no permanent displacement of the particles of the medium (i.e. little or no associated mass transport); instead there are oscillations around almost fixed positions.
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shoal is a somewhat linear landform within or extending into a body of water, typically comprised of sand, silt or small pebbles. Alternatively termed sandbar or sandbank
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reef is a rock, sandbar, or other feature lying beneath the surface of the water yet shallow enough to be a hazard to ships. Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but the
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ship is a large watercraft capable of offshore navigation. Ships may be operated by:
  • Governments (military, rescue, research, transportation)
  • Private companies and institutions (transportation, offshore resources, research)
  • Individuals (large yachts, research).

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worldwide view.
Hydrographic survey in its strictest sense is the process of gathering information about navigable waters for the purposes of safe navigation of vessels.
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Topography (Greek topos, "place", and graphia, "writing") is the study of Earth's surface features or those of planets, moons, and asteroids.

In a broader sense, topography is concerned with local detail in general, including not only relief but also
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bathymetric chart is the submerged equivalent of an above-water topographic map. Bathymetric charts are designed to present accurate, measurable description and visual presentation of the submerged terrain.
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worldwide view.

This article or section deals primarily with the United Kingdom and does not represent a worldwide view of the subject.
Please [ improve this article] or discuss the issue on the talk page.

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Flow may refer to:
  • Flow (physics) is the flux times the area. This is the rate at which something travels through a given cross section.

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Water quality is the physical, chemical and biological characteristics of water, characterized through the methods of hydrometry. The primary bases for such characterization are parameters which relate to drinking water, safety of human contact and for health of ecosystems.
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river is a natural waterway that transits water through a landscape from higher to lower elevations. It is an integral component of the water cycle. The water within a river is generally collected from precipitation through surface runoff, groundwater recharge (as seen at baseflow
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Drinking water is water that is intended to be ingested by humans. Water of sufficient quality to serve as drinking water is termed potable water whether it is used as such or not.
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James Whistler may refer to:
  • James McNeill Whistler, a 19th century British painter best known for painting Whistler's Mother
  • James Whistler (Prison Break character), A fictional character on the TV series Prison Break

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Cartography is the study of map making and cartographers are map makers.

Before 1400

  • Anaximander, Greek Anatolia, (610 BC-546 BC), first to attempt making a map of the (known) world

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A hydrographic office is an organization which is devoted to acquiring and publishing hydrographic information.

Historically, the main tasks of hydrographic offices were the conduction of hydrographic surveys and the publication of nautical charts.
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Headquarters
(and largest city)
Official languages French, English
Establishment 1921
Website
[1] The International Hydrographic Organization
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Cartography or mapmaking (in Greek chartis = map and graphein = write) is the study and practice of making representations of the Earth on a flat surface.
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drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region.
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Evapotranspiration (ET) is a term used to describe the sum of evaporation and plant transpiration from the earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies.
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flood is an overflow of an expanse of water that submerges land, a deluge.[1] In the sense of "flowing water", the word is applied to the inflow of the tide, as opposed to the outflow or "ebb".
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Hydrology (from Greek: Yδωρ, hudōr, "water"; and λόγος, logos, "knowledge") is the study of the movement, distribution, and quality of water throughout the Earth, and thus addresses both the hydrologic cycle and water resources.
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water cycle.]]

The Earth's water is always in movement, and the water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth.
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Hydrometeorology is a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere.

See also

  • Hydrological transport model
  • Hydrometry

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Hydrometry is the monitoring of the components of the hydrological cycle including rainfall, groundwater characteristics, as well as water quality and flow characteristics of surface waters.
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aqueduct is an artificial channel that is constructed to convey water from one location to another. The word is derived from the Latin aqua, "water," and ducere, "to lead.
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