Endorheic basin
Closed drainage basins with no outflow to oceans.
An endorheic basin (also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers and oceans. Instead, water drainage flows into permanent and seasonal lakes and swamps that equilibrate through evaporation. Endorheic basins are also called closed basins, terminal basins, and internal drainage systems. They constitute local base levels, defining a limit of the erosion and deposition processes of nearby areas.
- highest_percentage_by_continent
- Australia at 21%; Antarctica has about 18%, which is higher than North America's 5-10%.
Lore & Background
Endorheic basins are typically located in the interior of a landmass, far from an ocean, and in areas of relatively low rainfall. Their watersheds are often confined by natural geologic land formations such as a mountain range, cutting off water egress to the ocean. The inland water flows into dry watersheds where the water evaporates, leaving a high concentration of minerals and other inflow erosion products. Over time this input of erosion products can cause the endorheic lake to become relatively saline (a 'salt lake'). Since the main outflow pathways of these lakes are chiefly through evaporation and seepage, endorheic lakes are usually more sensitive to environmental pollutant inputs than water bodies that have access to oceans, as pollution can be trapped in them and accumulate over time.
Reader's Guide
Endorheic basins are significant because they represent a major component of Earth's hydrological system, covering about 18% of the planet's land area. They are most commonly found in desert locations, reflecting the balance between tectonic subsidence and rates of evaporation and sedimentation. These basins are vulnerable to pollution and climate change: because water can only leave through evaporation or seepage, pollutants and salts accumulate, and human activities such as dam construction have caused many endorheic lakes to contract dramatically, increasing salinity and disrupting ecosystems. The desiccation of saline lakes produces fine dust particles that impair agriculture productivity and harm human health. Anthropogenic activity has also caused a redistribution of water from these hydrologically landlocked basins, contributing to sea level rise. Notable examples include the Caspian Sea, the Chad Basin, and the Okavango Delta.
Did You Know?
- The term 'endorheic' derives from French 'endoréisme', combining Greek 'éndon' (within) and 'rheîn' (flow).
- The Black Sea is sometimes speculated to have been an endorheic lake, but the geological consensus is that it had outflow via the Bosporus and was not strictly endorheic.
- Australia has the highest percentage of endorheic regions at 21%, while Antarctica has about 18%, higher than North America's 5-10%.
- Endorheic basins often contain extensive salt pans, which are sometimes used for aviation runways or land speed record attempts.
Frequently Asked Questions
What exactly is an endorheic basin?
It is a drainage area in which water has no channel or pathway to reach the ocean or any other external water body. Rainfall and runoff instead collect in lakes, swamps, or salt flats within the basin and ultimately vanish through evaporation.
How does water actually leave an endorheic basin if there is no outflow?
Because no river or stream carries water out of the system, evaporation into the atmosphere is the only real exit. The internal lakes and wetlands shrink and expand seasonally until a moisture balance is reached.
What other terms do geomorphologists use for endorheic basins?
You will also encounter the labels closed basin, terminal basin, and internal drainage system in the literature. All three names highlight the same defining trait: no hydrological connection to the outside world.
Which continents have the highest share of endorheic basins?
Australia leads with roughly 21 percent of its land area falling within closed drainage systems. Antarctica follows at about 18 percent, while North America registers a lower 5 to 10 percent.
Why do endorheic basins matter for erosion and deposition in nearby terrain?
They serve as local base levels, setting the lowest elevation to which surrounding rivers and streams can erode. This imposes a hard limit on how far fluvial processes can carve valleys or deposit sediment in the adjacent landscape.
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