The largest endorheic lake also happens to be the largest overall lake in the world.
What is an Endorheic Lake?
An endorheic lake is a lake that doesn’t drain towards the ocean. The word endorheic stems from Ancient Greek: ἔνδον, éndon, “within” and ῥεῖν, rheîn, “to flow”. These lakes are also known as terminal lakes, closed lakes, or sink lakes.
The local topography prevents these lakes from eventually draining towards the ocean via rivers. Endorheic lakes are typically found far inland and are most common in desert regions. The main loss of water from these types of lakes occurs through evaporation and seepage.
The World’s Largest Lake
The largest endorheic lake in the world is the Caspian Sea.
The Caspian Sea is also the largest lake on Earth when calculating by both area and volume with a surface area of 371,000 square kilometers (143,000 square miles). The lake’s volume is 78,200 cubic kilometres (18,800 cubic miles).
The Caspian Sea is also the largest saline water-body in the world that doesn’t have ocean access.
The Caspian Sea is oriented in a north-south direction, with a length of about 1,000 kilometers (600 miles) from Kazakhstan to Iran.
The Caspian Sea is bordered by five countries: Russia to the north, Kazakhstan to the northeast, Turkmenistan to the southeast, Iran to the south, and Azerbaijan to the west.
How big is the Caspian Sea?
The sea’s surface area is approximately 143,200 square miles (371,000 square kilometers), making it roughly the size of Montana or Germany. Its maximum depth is around 3,360 feet, making it one of the world’s deepest lakes. The Caspian Sea is also an important source of oil and natural gas, with extensive deposits located beneath its waters and the surrounding region.
The northern part of the lake is the shallowest with depths of around 5 to 6 meters (16 to 20 feet) deep. The southern part of the lake is the deepest with depths of more than 1,000 meters (3,300 feet).
Sources of water for the Caspian Sea
Over 130 rivers empty into the Caspian Sea.
The Volga River, Europes longest river and which flows through central Russia, is the largest source of water and flows into the Caspian Sea from the north. The Volga River brings significant amounts of freshwater into the Caspian Sea, which helps to regulate its salinity levels and supports a range of aquatic life.
The Caspian Sea loses water only by evaporation.
A unique ecology
The Caspian Sea is also notable for its unique ecology.
Due to its high salinity, it has a distinctive set of plant and animal species, many of which are adapted to life in this extreme environment. For example, the Caspian seal, a critically endangered species, is found only in the waters of the Caspian Sea.
Additionally, the sea is home to a wide range of commercially important fish species, including sturgeon, which is prized for its caviar.
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References
Waterbodies that don’t flow to the sea. (2008). Newsletter and Technical Publications United Nations Environ. Program.
Caspian Sea. (2010). NASA Earth Observatory.
Huseynov, S. (2012). Fate of the Caspian Sea. Natural History Magazine.
