Drainage basin

Illustration of a drainage basin. The dashed line is the main water divide of the hydrographic basin.
Digital terrain map of the Latorița River's drainage basin in Romania
Digital terrain model of the Latorița River's drainage basin in Romania

A drainage basin is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. The drainage basin includes all the surface water from rain runoff, snowmelt, and nearby streams that run downslope towards the shared outlet, as well as the groundwater underneath the earth's surface.[1] Drainage basins connect into other drainage basins at lower elevations in a hierarchical pattern, with smaller sub-drainage basins, which in turn drain into another common outlet.[2]

Other terms used interchangeably with drainage basin are catchment area, catchment basin, drainage area, river basin, and water basin.[3] In North America, the term watershed is commonly used to mean a drainage basin, though in other English-speaking countries, it is used only in its original sense, that of a drainage divide.

In a closed drainage basin, or endorheic basin, the water converges to a single point inside the basin, known as a sink, which may be a permanent lake, a dry lake, or a point where surface water is lost underground.[4]

The drainage basin acts as a funnel by collecting all the water within the area covered by the basin and channelling it to a single point. Each drainage basin is separated topographically from adjacent basins by a perimeter, the drainage divide, making up a succession of higher geographical features (such as a ridge, hill or mountains) forming a barrier.

Drainage basins are similar but not identical to hydrologic units, which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system. Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins.[4]

Major drainage basins of the world


Major continental divides, showing drainage into the major oceans and seas of the world.
Drainage basins of the principal oceans and seas of the world. Grey areas are endorheic basins that do not drain to the oceans.

Ocean basins

The following is a list of the major ocean basins:

Largest river basins

The five largest river basins (by area), from largest to smallest, are the basins of the Amazon (7M km2), the Congo (4M km2), the Nile (3.4M km2), the Río de la Plata (3.2M km2), and the Mississippi (3M km2). The three rivers that drain the most water, from most to least, are the Amazon, Ganga, and Congo rivers.[5]

Endorheic drainage basins

Endorheic drainage basins are inland basins that do not drain to an ocean. Around 18% of all land drains to endorheic lakes or seas or sinks. The largest of these consists of much of the interior of Asia, which drains into the Caspian Sea, the Aral Sea, and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert, the drainage basin of the Okavango River (Kalahari Basin), highlands near the African Great Lakes, the interiors of Australia and the Arabian Peninsula, and parts in Mexico and the Andes. Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins.

In endorheic bodies of standing water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this is the Dead Sea.

Other Languages
Afrikaans: Opvanggebied
العربية: مستجمع مائي
aragonés: Compleganza
azərbaycanca: Çay hövzəsi
башҡортса: Йылға бассейны
беларуская: Вадазбор
беларуская (тарашкевіца)‎: Вадазбор
भोजपुरी: नदी थाला
bosanski: Sliv
brezhoneg: Diazad doureier
Cebuano: Tubig-saluran
čeština: Povodí
Deutsch: Einzugsgebiet
eesti: Valgla
Esperanto: Akvokolekta areo
français: Bassin versant
한국어: 유역
हिन्दी: जलसम्भर
hrvatski: Slijev
Bahasa Indonesia: Daerah aliran sungai
עברית: אגן ניקוז
қазақша: Өзен алабы
Kiswahili: Beseni
Kreyòl ayisyen: Basen drenaj
Кыргызча: Дарыя алабы
latviešu: Sateces baseins
lumbaart: Basin imbrìfer
македонски: Слив
მარგალური: წყარმალუშ ღანჩო
Bahasa Melayu: Lembangan saliran
မြန်မာဘာသာ: ရေဝေကြော
Nederlands: Stroomgebied
नेपाली: जलाधार
日本語: 流域
Nordfriisk: Iintoochregiuun
norsk nynorsk: Nedslagsfelt
олык марий: Вӱдкундем
polski: Dorzecze
саха тыла: Өрүс бассейна
shqip: Pellgu
slovenčina: Povodie
slovenščina: Porečje
српски / srpski: Слив
srpskohrvatski / српскохрватски: Sliv
தமிழ்: வடிநிலம்
татарча/tatarça: Сулык бассейны
тоҷикӣ: Обхез
Türkçe: Havza
Türkmençe: Basseýn
українська: Басейн річки
Tiếng Việt: Lưu vực
中文: 流域