Lake Balkhash

Lake Balkhash, also known as Lake Balqash, is a lake in southeastern Kazakhstan. It is one of the largest lakes in Asia and the 15th largest in the world. It is located in the eastern part of Central Asia and sits in the Balkhash-Alakol Basin, an endorheic (closed) basin. The basin drains seven rivers, the primary of which is the Ili, bringing most of the riparian inflow; others, such as the Karatal, bring surface and subsurface flow. The Ili is fed by precipitation, largely vernal snowmelt, from the mountains of China's Xinjiang region.

The lake currently covers about 16,400 km2 (6,300 sq mi). However, like the Aral Sea, it is shrinking due to diversion and extraction of water from its feeders. The lake has a narrow, quite central, strait. The lake's western part is fresh water and its eastern half is saline. The eastern part is on average 1.7 times deeper than the west. The largest shore city is named Balkhash and has about 66,000 inhabitants. Main local economic activities include mining, ore processing and fishing.

There is concern about the lake's shallowing due to desertification of microclimates and water extraction for multiplied industrial output. Moreover, the impacts of climate change may also negatively affect the lake and its ecosystems.

History and naming

The present name of the lake originates from the word "balkas" of Tatar, Kazakh and Southern Altai languages which means "tussocks in a swamp".

From as early as 103 BC up until the 8th century, the Balkhash polity surrounding the lake, whose Chinese name was Yibohai 夷播海, was known to the Chinese as 布谷/布庫/布蘇 "Bugu/Buku/Busu." From the 8th century on, the land to the south of the lake, between it and the Tian Shan mountains, was known in Turkic as Jetisu "Seven Rivers" (Semirechye in Russian). It was a land where the nomadic Turks and Mongols of the steppe mingled cultures with the settled peoples of Central Asia.

Beginning in 1759, the lake marked the northwesternmost limit of Qing suzerainty as recognized by the Qing and Russians. In 1864, the lake and its neighboring area were ceded to the Russian Empire under the Treaty of Tarbagatai. With the dissolution of the Soviet Union in 1991, the lake became part of Kazakhstan.

Origin of the lake

Balkhash lies in the deepest part of the vast Balkhash-Alakol depression, which was formed by a sloping trough between mountains of the Alpine orogeny and the older Kazakhstan Block during the Neogene and Quaternary. Rapid erosion of the Tian Shan has meant the depression subsequently filled with sand river sediments in what is geologically a very short timespan. The basin is a part of Dzungarian Alatau, which also contains lakes Sasykkol, Alakol, and Aibi. These lakes are remnants of an ancient sea which once covered the entire Balkhash-Alakol depression, but was not connected with the Aral–Caspian Depression.

Description

All the rivers of this region that carry their waters from high mountains flow into Lake Balkhash, however, none of them flows out. The major ones are: Ili, Aksu and Karatal. River Tokrau flows from the north, but its waters get lost in the sands before reaching the lakeshore. The lake is divided into two parts by the Saryesik peninsula (which means "Yellow Door" in the Kazakh language). These two parts are connected by the Uzynaral strait. In ancient times Balkhash was much larger and many lakes in the area were part of it, such as Zhalanashkol, Itishpes, Alakol and Sasykkol. Even farther back it was a sea, stretching all the way to the Dzungarian Alatau.

As recently as 1910 the lake was considerably larger with an estimated area of 23,464 km2. By 1946 this had shrunk by a nearly third, to 15,730 km2.

Relief

The lake has a surface area of about 16,400 km2 (2000), making it the largest lake wholly in Kazakhstan. Its surface is about 340 m above sea level. It has a gentle curve (sickle) shape yet with jagged shorelines. Its length is about 600 km and the width varies from 9–19 km in the eastern part to 74 km in the western part. Saryesik Peninsula, near the middle of the lake, hydrographically divides it into two very different lakes. The western lake covers 58% of the surface area but only 46% of the volume. It is thus relatively shallow, quiet and filled with freshwater. The eastern lake is much deeper and saltier. These parts are connected by the Uzynaral Strait (Kazakh: Ұзынарал – "long island") – 3.5 km wide and about 6 metres deep.

The lake includes several small basins. In the western part, are two depressions 7–11 meters deep. One extends from the western coast (near Tasaral Island) to Cape Korzhyntubek, whereas the second lies south from the Gulf Bertys, which is the deepest part of the "half". The average depth of the eastern basin is 16 m and the maximum depth is 26 m.

The average depth of the lake is 5.8 metres, and the total volume of water is about 112 km3.

The western and northern shores of the lake are high (20–30 m) and rocky; they are composed of such Paleozoic rocks as porphyry, tuff, granite, schist and limestone and keep traces of ancient terraces. The southern shores near the Gulf Karashagan and Ili River are low (1–2 m) and sandy. They are often flooded and therefore contain numerous water pools. Occasional hills are present with the height of 5–10 m. The coastline is very curvy and dissected by numerous bays and coves. The large bays of the western part are: Saryshagan, Kashkanteniz, Karakamys, Shempek (the southern pole of the lake), and Balakashkan Ahmetsu, and those in the eastern part are: Guzkol, Balyktykol, Kukuna, Karashigan. The eastern part also includes peninsulas Baygabyl, Balay, Shaukar, Kentubek and Korzhintobe.