Endorheic basin

Uureg Nuur

Wfm tarim basin

DeltaOkawango

Ocean drainage

Caspian Sea from orbit

Endorheic Basin

An endorheic basin is a closed drainage basin that retains water and allows no outflow to other external bodies of water, such as rivers or oceans. The water in these basins may evaporate or seep into the ground, making these areas unique ecosystems. Endorheic basins are often found in arid and semi-arid regions where evaporation greatly exceeds precipitation.

Characteristics

Endorheic basins are characterized by their inability to drain to the sea. This isolation from the global hydrological cycle significantly affects their hydrology, ecology, and water chemistry. Water balance within these basins is maintained through a delicate equilibrium between inflow—primarily from precipitation and sometimes from rivers or streams—and loss through evaporation or subsurface seepage.

Formation

The formation of endorheic basins is typically the result of tectonic activity and climatic changes. They can form in areas where rainfall is insufficient to drain away through rivers or where geological activity has created a closed depression. Over geological time scales, these basins can experience phases of isolation and connection with the global hydrological system.

Examples

Some of the most notable examples of endorheic basins include the Caspian Sea, the world's largest inland body of water, and the Great Basin in the United States. Other examples are the Aral Sea, which has significantly shrunk in recent decades, and Lake Chad in Africa.

Ecological and Environmental Concerns

Endorheic basins are sensitive to environmental changes and human activities. Because they are closed systems, any alteration in water balance can lead to significant changes in water level and salinity. This can affect the unique ecosystems that have adapted to these conditions. The Aral Sea is a stark example of how diversion of inflowing rivers for irrigation purposes can lead to ecological disaster.

Economic and Social Impact

Regions within endorheic basins often face water scarcity challenges, impacting agriculture, industry, and the livelihoods of local communities. The management of water resources in these areas requires careful planning to balance human needs with the preservation of ecosystems.

See Also

• Hydrology
• Water cycle
• Saline lake
• Desertification