Озеро Балхаш: География, экология и история

Lake in southeastern Kazakhstan

Lake Balkhash (, Balqaş kölı, ; озеро Балхаш) is a lake in southeastern Kazakhstan, 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 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.

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. 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.

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 time span. 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.

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 to 15,730 km2.

The lake covers 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 ( – "long island") – 3.5 km wide and about 6 metres deep. however, new islands are being formed due to the lowering of water level, and the area of the existing ones is increasing. The islands of the western part include Tasaral and Basaral (the largest), as well as Ortaaral, Ayakaral and Olzhabekaral. The eastern islands include Ozynaral, Ultarakty, Korzhyn and Algazy.

Balkhash is a semi saline lake. Chemical composition strongly depends on the hydrographic features of the reservoir. Water in the west half is nearly fresh, with the content of total dissolved solids about 0.74 g/L, and cloudy (visibility: 1 metre); it is used for drinking and industry. The east half has less silt in suspension (visibility: 5.5 metres) but resembles oceanic sea water in salinity, with concentration of 3.5–6 g/L. The water in the western part has a yellow gray tint, and in the eastern part the color varies from bluish to emerald blue.

The economic importance of the lake is mostly in its fishing industry. Systematic breeding of fish began in 1930;

Energy supply to the south eastern part of Kazakhstan is an old problem, with numerous solutions proposed in the past. Proposals to build power plants on Balkhash in the late 1970s and 1980s stalled, and the initiative to erect a nuclear plant near the village Ulken met strong opposition from environmentalists and residents. Therefore, in 2008, the Kazakh government reconsidered and announced building of a Balkhash Thermal Power Plant.

There is a regular ship navigation through the lake, the mouth of the Ili River, and the Kapchagay Reservoir. The main piers are Burylbaytal and Burlitobe. are relatively light due to the limiting depth in some parts of the lake; they are used mainly for catching fish and transporting fish and construction materials. The total length of the waterway is 978 km, and the navigation period is 210 days/year. Navigation on the Lake Balkhash originated in 1931 with the arrival of two steamers and three barges. By 1996, up to 120,000 tonnes of building materials, 3,500 tonnes of ore, 45 tonnes of fish, 20 tonnes of melons and 3,500 passengers were transported on Balkhash (per year). During 2004 there were 1000 passengers and 43 tonnes of fish. In 2004, the local fleets consisted of 87 vessels, including 7 passenger ships, 14 cargo barges and 15 tugboats. The government projected that 2012 would see in the Ili Balkhash basin 233,000 tonnes of construction materials, at least 550,000 tonnes of
livestock, fertiliser and foodstuffs and at least 53 tonnes of fish. Development of eco tourism is expected to increase the passengers to 6,000 people per year.

Academics and government advisors fear major loss of ecosystems in the lake. Salt dust is blown away from the dried areas, contributing to the generation of Asian dust storms, increase the soil salinity and adversely influencing the climate. Increasing formation of silt in the river's delta further reduces the inflow of water to the lake. In 2007, the Kazakhstan government proposed a price reduction for sales of Kazakh products to China in exchange for reduction of water consumption from Ili River, but the offer was declined by China.