Lake Van

Lake Van is the largest lake located in Turkey.

It sits in the Eastern Anatolia region within the Armenian highlands. The lake spans across the provinces of Van and Bitlis. It is a saline soda lake, which means its water is very salty. This lake is also an endorheic lake. An endorheic lake is a body of water that has no outlet to the sea. Because it holds so much water, it contains 38% of the surface water in Turkey.

The lake's unique chemistry comes from its high levels of sodium carbonate and other salts. This makes the water strongly alkaline, with a pH between 9.7 and 9.8. This high salinity affects how the lake reacts to the cold. Even when winter temperatures drop below 0°C, the lake usually does not freeze. Only the shallow northern section might freeze, but this is rare. The lake's water is also used by people. Some salt is extracted from evaporation ponds to be used in detergents.

Geologically, Lake Van is a tectonic lake. It formed more than 600,000 years ago. This happened because a large block of the Earth's crust sank. This sinking was caused by movement on several major faults in Eastern Anatolia. The lake's location is near the Karlıova triple junction. This proximity means molten fluids from the Earth's mantle collect in the strata below. This activity still causes gradual changes in the region today.

Volcanic activity has played a massive role in the lake's history. Originally, Lake Van had an outlet to the southwest. This outlet led to the Murat River and eventually the Euphrates River. However, successive lava flows from the Mount Nemrut volcano blocked this path. These flows moved toward the Muş Plain and closed the outlet. This turned the lake into the endorheic system we see now. The stratovolcano Mount Süphan also dominates the northern shore of the lake.

Researchers have studied the lake's depth and shape using acoustic surveys. In 1974, the first acoustic survey was performed. Scientists identified three distinct provinces within the lake. First is the lacustrine shelf, which covers 27% of the lake. Second is a steeper lacustrine slope that makes up 63%. Finally, there is a deep, flat basin province covering 10%. The deepest part is the Tatvan basin. This basin is almost completely surrounded by faults.

The history of the lake is also found in its changing water levels. Geologists have found land terraces that show where the shore used to be. In 1898, Felix Oswald noted three raised beaches at 5, 15, and 30 meters above the water. The PALEOVAN project has used sediment cores to study these changes. They found that the lake level has varied by as much as 1,600 meters over 600,000 years. During the last 90,000 years, the level has shifted due to climate and volcanic events. For example, a rapid rise occurred about 34,000 years ago. This might have been caused by meltwater or volcanic debris from Mount Nemrut.

Ancient civilizations have lived around Lake Van for thousands of years. The lake was the center of the kingdom of Urartu around 1000 BC. It was also part of the Armenian kingdom. In 2017, divers discovered a massive underwater fortress. This fortress is roughly one kilometer long. Archaeologists believe it was built during the Urartian period. They think the rising lake level eventually submerged the fortress and the surrounding city.

Life in the lake is specialized due to the alkaline water. Before 2018, the only known fish was the Pearl Mullet. This fish migrates to rivers in the spring to spawn. In 2018, a new fish species was discovered inside a microbialite. Microbialites are solid towers on the lake bed. They are formed by cyanobacteria that create mats of aragonite and calcite.

Many different organisms live in these waters. There are 103 recorded species of phytoplankton, such as diatoms and algae. There are also 36 species of zooplankton. The region is also home to the rare Van cat. These cats are known for their unusual fascination with water.