Sajun.org
:''For a term related to television programmes, see
watershed (television).''
A '''watershed''' or '''water basin''' is the region of land that drains into a specified
body of water, such as a
river,
lake,
sea, or
ocean.
Rain that falls anywhere within a given body of water's watershed will eventually drain into that body of water. A map of the primary watersheds in the world can be found at
[1].
The term ''watershed'' can also mean the
topographical dividing line between water basins: watersheds usually run along
mountain ridges. Current usage is
watershed divide.
Each area of a drainage basin has its own
drainage system.
== 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.
== 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 majority of Canada's land area.
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.
== 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
Caribbean Sea watershed consists of all of the
American interior (the
Louisiana Purchase, which involved the watershed of the
Mississippi River); eastern
Central America; and far northern
South America.
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.
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.
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).
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.
==Watersheds in the
curriculum==
As the linked forces of curricular reform and standards-based assessment continue to delineate important ideas and skills to learn in science and other subjects, there is a growing need to identify focal points for organizing school programs. Locally relevant topics are needed to connect concept and skill development across subject areas and grade levels. A study of watersheds can serve this role; everyone on earth lives within a watershed; the quality of life is greatly affected by the condition of the local watershed; and watersheds can serve as an instructional focus for active learning in science, mathematics, social studies, environmental education, and other subject areas. Here are some examples:
* A watershed's
geological history and
hydrological processes teach elements of
earth science.
* Analysis of the chemical and biological parameters of a river teaches physical and
biological sciences.
* The gathering of quantitative, empirical data involves students in
statistics and
mathematics.
* Land and water use within a watershed provide a context for the
social sciences in watershed management.
Furthermore, the study of watersheds provides the perfect forum for engaging community partners in the school curriculum. Many local issues relate to the supply and protection of
drinking water, and many occupations relate to monitoring and managing the
environmental health of watersheds.
See the
Bryant Creek Watershed Atlas link below. This is an educational website focusing on all aspects of a local watershed in the southern
Missouri Ozarks that is a tributary of the
White River in
Arkansas.
== See also==
*
List of watersheds (a list of the largest watersheds of the world)
*
Hydrology
*
River
*
Watersheds of Indiana
== External links==
*
Map of primary watersheds in the world
*
Studying Watersheds: A Confluence of Important Ideas
*
'''Bryant Creek Watershed Atlas'''de:Wasserscheide
et:Valgla
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ja:分水界
nl:stroomgebied
zh:流域
simple:Watershed
