A watershed is a region of land where water drains downhill into a specified body of water, such as a river, lake, sea, ocean or wetland. A watershed includes both the waterway and the land that drains to it. Each watershed is separated topographically by a ridge, hill or mountain. A watershed is like a funnel - collecting all the water within the drainage area and channeling it into a waterway. A body of water is any significant natural pool of water such as an ocean, a lake, or a river, covering the Earth or another planet. ... The Murray River in Australia. ... A Lake is a body of water surrounded by land. ... Sunset at sea Look up Sea on Wiktionary, the free dictionary Look up maritime on Wiktionary, the free dictionary. ... The worlds oceans as seen from the South Pacific Ocean (from Okeanos, Greek for river, the ancient Greeks noticed that a strong current flowed off Gibraltar, and assumed it was a great river); covers almost three quarters (71%) of the surface of the Earth, and nearly half of the... A subtropical wetland in Florida, USA, with an endangered American Crocodile. ...

So defined it may also be called a water basin or catchment basin, and this is the sense intended in this article, unless otherwise indicated. In many contexts, however, watershed is used to mean a water divide, a boundary between water basins.^[1] A water divide, or watershed, is relatively high ground between water basins. ...

Rain that falls anywhere within a given body of water's watershed or basin will eventually drain into that body of water. A map of the primary watersheds in the world can be found at [1]. A watershed that drains into a river is usually known as a river basin. Rain falling For other uses see Rain (disambiguation). ...

Each area of a drainage basin has its own drainage system. A drainage system is the pattern formed by the streams, rivers, and lakes in a particular watershed. ...

Watersheds in ecology

Watersheds constitute a very important type of ecoregion. They do things such as provide habitats for animals, lessen flooding, and prevent erosion. Pollution anywhere within the watershed can potentially affect life anywhere downstream from it. An ecoregion is a relatively large area of land or water that contains a geographically distinct assemblage of natural communities. ... Environmental Pollution is the release of harmful environmental contaminants, or the substances so released. ...

Watersheds in politics

Watersheds have been important historically in determining boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the Indian trade in the entire Hudson Bay watershed, an area called Rupert's Land. The company later acquired the North American watershed of the Arctic Ocean (the North-Western Territory). These lands later became part of Canada as the Northwest Territories, making up the vast majority of Canada's land area. Wikimedia Commons has media related to: England Travel guide to England from Wikitravel English language English law English (people) List of monarchs of England – Kings of England family tree List of English people Angeln (region in northern Germany, presumably the origin of the Angles for whom England is named) UK... The Hudsons Bay Company (HBC) TSX: HBC is the oldest corporation in Canada (and the second oldest in North America) and is one of the oldest in the world still in existence. ... Hudson Bay, Canada. ... Ruperts Land Ruperts Land was a territory consisting of much of modern Canada. ... The North-Western Territory at its greatest extent, 1859 The North-Western Territory was a region of British North America until 1870. ... Motto: None Other Canadian provinces and territories Capital Yellowknife Largest city Yellowknife Commissioner Tony Whitford Premier Joe Handley (Consensus government - no party affiliations) Area 1,346,106 km² (3rd) Land 1,183,085 km² Water 163,021 km² (12. ...

Today, bioregional democracy can include agreements of states in a particular watershed to defend it. These include the Great Lakes Commission, which deals with the largest fresh watershed in the world. Bioregional democracy (or the Bioregional State) is a set of electoral reforms designed to force the political process in a democracy to better represent concerns about the economy, the body, and environmental concerns (e. ... Great Lakes. ...

Analyzing watersheds

Rain gauge data is used to measure total precipitation over a watersheds, and there are different ways to interpret that data.

If the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In mathematics and statistics, the arithmetic mean of a set of numbers is the sum of all the members of the set divided by the number of items in the set (cardinality). ...

In the Thiessen polygon method, the watershed is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for the rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. This is the Voronoi diagram of a random set of points in the plane (all points lie within the image). ...

The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time consuming. An isohyet is a line joining places of equal precipitation on a map. ...

Ocean watersheds

One can divide up the world among the watersheds of the oceans and largest seas.

The Atlantic Ocean watershed consists of the Saint Lawrence River and Great Lakes watersheds, plus the Eastern Seaboard, Canadian Maritimes, Newfoundland and Labrador in North America; nearly all of South America (that portion east of the Andes); northern Europe; and the greatest portion of western Sub-Saharan Africa. The Saint Lawrence River (French: fleuve Saint-Laurent) is a large west-to-east flowing river in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. ... The Great Lakes from space The Great Lakes are a group of five large lakes on or near the United States-Canadian border. ... Categories: US geography stubs ... The Maritimes or Maritime provinces are a region of Canada on the Atlantic coast, consisting of New Brunswick, Nova Scotia and Prince Edward Island. ... This is about the Canadian province of Newfoundland and Labrador. ... World map showing North America A satellite composite image of North America North America is a continent in the northern hemisphere bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... The Andes between Chile and Argentina Satellite Image of the Andes (Source:http://earthobservatory. ... A satellite composite image of Europe // Etymology Picture of Europa, carried away by bull-shaped Zeus. ... A satellite composite image of Africa showing the ecological break between North and Sub-Saharan regions Sub-Saharan Africa, Africa south of the Sahara, is the term used to describe those countries of Africa that are not part of North Africa or some areas of West Africa. ...

The Caribbean Sea watershed consists of all of the American interior (the Louisiana Purchase, the western Mississippi River watershed; as well as the eastern half such as the Ohio River and its tributaries); eastern Central America; and far northern South America. Map of Central America and the Caribbean The Caribbean Sea is a tropical body of water adjacent to the Atlantic Ocean and southeast of the Gulf of Mexico. ... From Frank Bond, Louisiana and the Louisiana Purchase. ... This page is about the river in the United States; there is also a Canadian Mississippi River (Ontario). ... Commonly, Central America is the region of North America located between the southern border of Mexico and the northwest border of Colombia, in South America. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...

The Mediterranean Sea watershed consists of much of northeastern Africa, including Egypt, Libya, and Sudan (the Nile watershed), as well as southern and eastern Europe, Turkey, and the Levant. Satellite image The Mediterranean Sea is a part of the Atlantic Ocean almost completely enclosed by land, on the north by Europe, on the south by Africa, and on the east by Asia. ... // Etymology World map showing Africa (geographically) The name Africa came into Western use through the Romans, who used the name Africa terra — land of the Afri (plural, or Afer singular) — for the northern part of the continent, as the province of Africa with its capital Carthage, corresponding to modern-day... The Nile (Arabic: النيل an-nīl), in Africa, is one of the two longest rivers on Earth. ... The Levant Levant is an imprecise geographical term historically referring to a large area in the Middle East south of the Taurus Mountains, bounded by the Mediterranean Sea on the west, and by the northern Arabian Desert and Upper Mesopotamia to the east. ...

Of course, the previous two can be considered part of the Atlantic watershed, since the Caribbean Sea is part of the Atlantic Ocean, and the Atlantic drains into the Mediterranean due to its higher evaporation.

The Indian Ocean watershed consists of the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf, the Indian subcontinent, Burma, and most of Australia. Location of the Red Sea The Red Sea (Arabic البحر الأحمر Baḥr al-Aḥmar, al-Baḥru l-’Aḥmar; Hebrew ים סוף Yam Suf; Tigrigna ቀይሕ ባሕሪ QeyH baHri) is a gulf or basin of the Indian Ocean between Africa and Asia. ... Map of the Persian Gulf. ... Composite satellite image of the Indian subcontinent Map of South Asia. ...

The Pacific Ocean watershed consists of much of China, southeastern Russia, Japan, Korea, most of Indonesia and Malaysia, the Philippines, the rest of the Pacific islands, and the northeast coast of Australia; as well as Alaska, British Columbia, the western United States and Central America, and the coast of South America (the smaller portion west of the Andes). Korea refers to South Korea and North Korea together, which were a unified country until 1948. ... State nickname: The Last Frontier, The Land of the Midnight Sun Official languages English Capital Juneau Largest city Anchorage Governor Frank Murkowski (R) Senators Ted Stevens (R) Lisa Murkowski (R) Area  - Total  - % water Ranked 1st 663,267 mi² / 1,717,854 km² 13. ... Motto: Splendor Sine Occasu (Latin: Splendour without diminishment) Official languages English Capital Victoria Largest city Vancouver Lieutenant-Governor Iona Campagnolo Premier Gordon Campbell (BC Liberal) Parliamentary representation  - House seat  - Senate seats 36 6 Area  - Total  - % water Ranked 5th 944,735 km² 2. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... The Andes between Chile and Argentina Satellite Image of the Andes (Source:http://earthobservatory. ...

The Arctic Ocean watershed consists of the aforementioned Rupert's Land, and most of the territory of Russia.

In addition to the oceanic watersheds, there are numerous endorheic watersheds, inland basins which drain into no ocean. The largest of these consists of much of the interior of Asia, and drains into the Caspian Sea and the Aral Sea. Other basins include the Great Basin in the United States, much of the Sahara Desert, the watershed of the Okavango River, highlands near the African Great Lakes, the interiors of Australia and the Arabian Peninsula, and parts in Mexico and the Andes. The shores of Lake Hart, an endorheic desert lake in South Australia In geography, an endorheic basin is a watershed from which there is no outflow of water (either on the surface as rivers, or underground by flow or diffusion through rock or permeable material). ... Asia is the largest and most populous of the Earths continents. ... Caspian Sea viewed from orbit The Caspian Sea is a landlocked endorheic sea between Asia and Europe (European Russia). ... Map of area around the Aral Sea. ... Map showing the Great Basin in orange The Great Basin is a large, arid region of the western United States, commonly defined as the contiguous watershed region, roughly between the Rocky Mountains and the Sierra Nevada, that has no natural outlet to the sea. ... The Sahara is the worlds second largest desert (second to Antarctica), over 9,000,000 km² (3,500,000 mi²), located in northern Africa and is 2. ... The Okavango River is a river in southwest Africa. ... The Great Lakes and the East African coastline as seen from space. ... The Arabian Peninsula The Arabian Peninsula is a mainly desert peninsula in Southwest Asia at the junction of Africa and Asia and an important part of the greater Middle East. ...

See also

• List of watersheds (a list of the largest watersheds of the world)
• Hydrology
• River

It has been suggested that this article or section be merged with List of drainage basins. ... Water covers 70% of the Earths surface. ... The Murray River in Australia. ...

Footnote

• 1. ^  Watershed meaning water basin predominates in American English, while the meaning water divide predominates in Commonwealth English.

American English (AmE) is the dialect of the English language used mostly in the United States of America. ... Commonwealth English is intended as a collective term for the perceived standard English language used in the Commonwealth of Nations1, applying in theory to Australian English, British English, Caribbean English, Canadian English, Hiberno-English (Irish English)2, Hong Kong English3, Indian English (includes Pakistani English), formal Malaysia English, New Zealand...

External links

• Map of primary watersheds in the world
• Studying Watersheds: A Confluence of Important Ideas
• Bryant Creek Watershed Atlas
• Santa Ana Watershed Information
• Science in Your Watershed