Largest Lakes in Turkey

Hydrology and chemistry

Lake Van is 119 kilometres (74 mi) across at its widest point. It averages 171 metres (561 ft) deep. Its greatest known depth is 451 metres (1,480 ft). The surface lies 1,640 metres (5,380 ft) above sea level and the shore length is 430 kilometres (270 mi). It covers 3,755 km2 (1,450 sq mi) and contains (has a volume of) 607 cubic kilometres (146 cu mi).

The western portion of the lake is deepest, with a large basin deeper than 400 m (1,300 ft) lying northeast of Tatvan and south of Ahlat. The eastern arms of the lake are shallower. The Van-Ahtamar portion shelves gradually, with a maximum depth of about 250 m (820 ft) on its northwest side where it joins the rest of the lake. The Erciş arm is much shallower, mostly less than 50 m (160 ft), with a maximum depth of about 150 m (490 ft).

Geology

Lake Van is primarily a tectonic lake, formed more than 600,000 years ago by the gradual subsidence of a large block of the Earth's crust due to movement on several major faults that run through this portion of Eastern Anatolia. The lake's southern margin demarcates: a metamorphic rock zone of the Bitlis Massif and volcanic strata of the Neogene and Quaternary periods. The deep, western portion of the lake is an antidome basin in a tectonic depression. This was formed by normal and strike-slip faulting and thrusting.

The lake's proximity to the Karlıova triple junction has led to molten fluids of the Earth's mantle accumulating in the strata beneath, still driving gradual change. Dominating the lake's northern shore is the stratovolcano Mount Süphan.

History

Tushpa, the capital of Urartu, near the shores, on the site of what became medieval Van's castle, west of present-day Van city. The ruins of the medieval city of Van are still visible below the southern slopes of the rock on which Van Castle stands.

In 2017, archaeologists from Van Yüzüncü Yil University and a team of independent divers who were exploring Lake Van reported the discovery of a large underwater fortress spanning roughly one kilometer. The team estimates that this fortress was constructed during the Urartian period, based on their visual assessments. The archaeologists believe that the fortress, along with other parts of the ancient city that surrounded it at the time, had slowly become submerged over the millennia by the gradually rising lake.

Ecology

Prior to 2018, the only fish known to live in the brackish water of Lake Van was Alburnus tarichi or Pearl Mullet (Turkish: inci kefali), a Cyprinid fish related to chub and dace, which is caught during the spring floods. In May and June, these fish migrate from the lake to less alkaline water, spawning either near the mouths of the rivers feeding the lake or in the rivers themselves. After spawning season it returns to the lake.

Geography

The lake, occupying a tectonic depression in the central plateau of Turkey, is fed by two major streams, groundwater, and surface water, but has no outlet. Brackish marshes have formed where channels and streams enter the lake. Arable fields surround the lake, except in the south and southwest, where there is an extensive seasonally flooded salt-steppe.

For most of the year, it is very shallow (approx.0.4 m (1 ft)). During winter part of the salt is dissolved in the fresh water that is introduced to the lake by precipitation and surface runoff (to 32-34% salinity). During the summer the lake dries up exposing an average of 30cm thick salt layer in August. This mechanism is used as a basis for the process of the salt mines in the lake.

Geology

Subsidence in the Tuz Gölü Lower Basin occurred during the Upper Senonian-Lower Middle Eocene and was followed by a regression that started in the upper Eocene and continued until the end of the Oligocene. During the Upper Senonian-Lower Middle Eocene, the Tuz Gölü Lower Basin formed a single and continuous depression towards the north with the Haymana region. The Haymana Basin, which rose after the deposition of the Middle Eocene Nummulitic limestones, separated the Tuz Gölü Basin with a fault zone along the eastern edge of the Karacadağ uplift.

The connection of Tuz Gölü with the north-northeast Çankırı basin occurred during the Pliocene period and continued throughout the Middle Eocene-Oligocene, when the lake basin became a graben bounded by the north-west and north-east fault zones.

History

In antiquity, Lake Tuz was known as Tatta and was situated on the frontier between ancient Lycaonia and Galatia. Initially part of Phrygia, the region was later annexed into Lycaonia. Ancient sources described the lake as highly saline, with water so rich in brine that that any substance dipped into it, was immediately encrusted with a thick coat of salt; even birds flying near the surface had their wings moistened with the saline particles, so as to become incapable of rising into the air, and to be easily caught. Stephanus of Byzantium speaks of a salt lake in Phrygia, which he calls Attaea (Ἄτταια), near which there was a town called Botieum, tentatively linked to the modern settlements of Şereflikoçhisar or Eskil.

Hydrology

Lake Eğirdir is fed by about 40 different springs, some of which are intermittent, and also by rainfall within its 3,309-km2 drainage basin. The main streams which feed Lake Eğirdir are the Pupa, the Hoyran, the Yalvaç, and the Çay. Besides evaporation, water exits Lake Eğirdir either by flowing out through the Kovada Canal into Lake Kovada, by draining out into one of the about 20 natural ponors that exist at the bottom of the lake, or by being pumped out through one of the 11 irrigation pumps built around the lake. The average retention time for water in the lake is 2.5 to 3 years.

The lake has an average depth of 7 m and a maximum depth of 13 m. Significant fluctuations in Lake Eğirdir's water level are not uncommon.

Geology

Lake Eğirdir forms part of the Eğirdir-Kovada graben, a north–south depression that also includes Lake Kovada. Two distinct stages of geological deposits are visible on dry land. Deposits from the first stage are exposed above ground in the Yeşilköy area; this is called the Yeşilköy Formation. This may have been deposited by the prehistoric Gölcük Volcano, 50 km to the southwest near the city of Isparta. The second phase is recent alluvial sedimentary deposits from Quaternary times, especially visible in areas around Eğirdir and Barla as well as around Lake Kovada.

This region is very seismically active; for example, in March 2007, a magnitude 5.1 earthquake happened on the lake's eastern shore, along the Esinyurt Fault; it was followed by 93 smaller aftershocks over a period of 4 days.

History

Lake Eğirdir must have existed in ancient times, since coins from the nearby city of Parlaos have been found with ships on them, but no clear references to the lake have been found in ancient texts, and its ancient name is unknown. A number of ancient settlements have been located around the lake: places whose names are known were Eğirdir itself (historically known as Akroterion), Parlaos, Malos, and Prostanna; and places whose ancient names are not known were at the ruin sites of Bedre, Ghaziri, and Ertokuş Han, as well as on Yeşil Ada. (Based on its modern name, Bedre – now known as Gökçe – may have been called "Petra" in ancient times.) In the 14th century, Ibn Batutta mentioned merchant shipping on the lake at Eğirdir (or Akrīdūr, as he called the city in Arabic).

Economy

The total economic value of commercial fishing on Lake Eğirdir has ranged between a low of US$50,526 in 2008 and a high of US$3,001,920 in 1977. The most profitable period was the decade from 1975 to 1985, when the annual yield ranged from $2–3 million USD. The most important fish species have historically been the Eurasian carp and the pike perch, while crayfish were the most important species overall between 1975 and 1985.