بالخاش دریاچهای واقع در جنوب شرقی قزاقستان است که پس از آرال بزرگترین دریاچههای درونبومی آسیای مرکزی است. اگر چه این دریاچه مخزنی ندارد، میزان شوری آن کم است و رود ایلی و چند رود دیگر به آن میریزد.
این دریاچه برای جغرافیدانان مسلمان در سدههای پیشین ناشناخته بود. قلموقها نخستین کسانی بودند که نام مغولی بالخاش را به این دریاچه دادند. این قوم در سده ۱۱ق و نیمه نخست سده ۱۲ق بر این مناطق تسلّط داشتند. سرزمین پیرامون بالخاش متروک و بسیار خشک است. این دریاچه تا زمان انقلاب اکتبر روسیه، از نظر اقتصادی نقشی نداشت. اهمیت این ناحیه، در ۱۹۳۶م، با بنای یک شهر بزرگ صنعتی به نام بالخاش در کرانه خلیج کوچک برتیس در ساحل شمالی دریاچه آغاز شد.
پیوند به بیرون[ویرایش]
Lake Balkhash (Kazakh: Balqas’ Ko’li; Russian: Озеро Балхаш, Ozero Balhaš) is one of the largest lakes in Asia and 15th largest in the world. It is located in Central Asia in southeastern Kazakhstan and belongs to an endorheic (closed) basin shared by Kazakhstan and China, with a small portion in Kyrgyzstan. The basin drains into the lake via seven rivers, the primary of which is the Ili River, bringing the majority of the riparian inflow; others, such as the Karatal, provide both 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 an area of about 16,400 km2 (6,300 sq mi). However, like the Aral Sea, it is shrinking as a result of the diversion of water from rivers that feed it. The lake is divided by a strait into two distinct parts. The western part is fresh water, while the eastern half is saline. The eastern part is on average 1.7 times deeper than the western section. The largest city near the lake is also named Balkhash and has about 66,000 inhabitants. Major industrial activities in the area include mining, ore processing and fishing.
While the size of the lake is temporarily growing, there is concern about the lake's shallowing due to desertification and industrial activity.
History and naming
From as early as 103 BC up until the 8th century, the Balkhash polity was known to the Chinese as 布谷/布库/布苏 "Pu-Ku/Bu-Ku". 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.
During China's Qing dynasty (1644–1911), the lake formed the northwestern-most boundary of the Empire. In 1864, the lake and its neighboring area were ceded to Imperial Russia under the Protocol of Chuguchak. With the dissolution of the Soviet Union in 1991, the lake became part of Kazakhstan.
The 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 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.
The lake has an area of about 16,400 km2 (2000), making it the largest lake which lies entirely within the territory of Kazakhstan. It is elevated about 340 m above sea level and has a sickle shape. 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, located near the middle of the lake, hydrographically divides it into two very different parts. The western part, which comprises 58% of the total lake area and 46% of its volume, is relatively shallow, quiet and is filled with freshwater, whereas the eastern part is much deeper and saltier. These parts are connected by the Uzynaral Strait (Kazakh: Ұзынарал – "long island") which is 3.5 km wide and about 6 m deep.
The lake includes several small basins. In the western part, there are two depressions 7–11 meters deep. One of them 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 western Balkhash. The average depth of the eastern basin is 16 m and the maximum depth of the eastern part (and of the lake) is 26 m. The average depth of the lake is 5.8 m, 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.
The lake contains 43 islands with a total area of 66 km2; 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.
Feeding the lake and the water level
Balkhash-Alakol Basin covers an area of 512,000 km2, and its average surface water runoff is 27.76 km3/year, of which 11.5 km3 come from the territory of China. The area of drainage basin of the lake is about 413,000 km2; with 15% belonging to the north-west of Xinjiang region in China and a small part in Kyrgyzstan. Lake Balkhash takes 86% of water inflow from Balkhash-Alakol basin. Ili River accounts for 73–80% of the inflow with the total volume quoted as either 12.3 km3/year or 23 km3/year. The river originates in Tian Shan mountains and is mainly fed by glacier. This results in daily and seasonal fluctuations of its water level with a strong increase during the glacier melting season in June–July. The river forms an extended delta which covers the area of 8,000 km2 and serves as an accumulator, providing water in the drought years.
The eastern part of the lake is fed by the rivers Karatal, Aksu and Lepsy, as well as by groundwater. The Karatal River originates on the slopes of Dzungarian Alatau and is the second largest water source for the lake. River Ayaguz, which fed the eastern part of the lake until 1950, barely reaches it nowadays. The annual difference in the flow to the western and eastern parts of the lake is 1.15 km3.
The area and volume of the lake vary due to long-term and short-term fluctuations in water level. Long-term fluctuations had an amplitude of 12–14 m, which was minimum between the 5th and 10th centuries and maximum between the 13th and 18th centuries. In the early 20th century and between 1958 and 1969, the area of the lake increased to ~18,000 km2, and during the droughts, for example in the late 1900s, 1930s and 1940s, the lake shrank to ~16,000 km2 with the water level fluctuations of about 3 m. In 1946, the area was 15,730 km2 and the lake volume was 82.7 km3. From the late 1900s, the lake is shrinking due to the diversion of the rivers supplying it. For example, Kapshagay Hydroelectric Power Plant was built on Ili River in 1970. Filling the associated Kapshagay Reservoir disbalanced Balkhash Lake, causing deterioration of water quality, especially in the eastern part of the lake. Between 1970 and 1987, the water level fell by 2.2 m, the volume reduced by 30 km3 and the salinity of the western part was increasing. Projects were proposed to slow the changes down, e.g. by splitting the lake in two with a dam, but were cancelled due to the economic decline in the Soviet Union.
The minimal water level in the lake (340.65 meters above sea level) was recorded in 1987, when the filling Kapshagay Reservoir was completed. The level rose to 342.5 m by January 2005 that was attributed to large volume of precipitations in the late 1990s.
Balkhash is a semi-saline lake, and the chemical composition of its water strongly depends on the hydrographic features of the reservoir. Water in the western part is nearly fresh, with the content of total dissolved solids about 0.74 g/L, and cloudy (visibility 1 m); it is used for drinking and industry. Water in the eastern part is more transparent (visibility 5.5 m) and saline, with the average salt concentration of 3.5–6 g/L. The average salinity of the lake is 2.94 g/L. Long-term (1931–1970) average precipitation of salts in Lake Balkhash is 7.53 million tonnes and the reserves of dissolved salts in the lake are about 312 million tonnes. 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 climate of the lake area is continental. Average temperature is about 30 °C in July and −14 °C in January. Average precipitation is 131 mm per year and the relative humidity is about 60%. Wind, dry climate and high summer temperatures result in high evaporation rate – 950 mm in cold and up to 1200 mm in dry years. Wind has average speed of 4.5–4.8 m/s and blows mainly southward in the western part and to the south-west in the eastern part. The wind induces waves up to 2–3.5 m in height and steady clockwise currents in the western part.
There are 110–130 sunny days per year with the average irradiance of 15.9 MJ/m2 per day. Water temperature at the surface of the lake varies from 0 °C in December to 28 °C in July. The average annual temperature is 10 °C in the western and 9 °C in the eastern parts of the lake. The lake freezes every year between November and early April, and the melting is delayed by some 10–15 days in the eastern part.
Flora and fauna
The shores of the lake contain individual willow trees and riparian forests, mostly composed of various species of Populus. Plants include common reed (Phragmites australis), lesser Indian reed mace (Typha angustata ) and several species of cane – Schoenoplectus littoralis, S. lacustris and endemic S. kasachstanicus. Under water grow two types of Myriophyllum – spiked (M. spicatum) and whorled (M. verticillatum); several kinds of Potamogeton – shining (P. lucens), perfoliate (P. perfoliatus), kinky (P. crispus), fennel (P. pectinatus) and P. macrocarpus; as well as common bladderwort (Utricularia vulgaris), rigid hornwort (Ceratophyllum demersum) and two species of Najas. Phytoplankton, the concentration of which was 1.127 g/L in 1985, is represented by numerous species of algae.
The lake used to have a rich fauna, but since 1970, biodiversity began to decline due to deterioration of water quality. Before then, there were abundant shellfish, crustaceans, chironomidae and oligochaeta, as well as zooplankton (concentration 1.87 g/L in 1985), especially in the western part. The lake hosted about 20 species of fish, 6 of which were native: Ili marinka (Schizothorax pseudoaksaiensis), Balkhash marinka (S. argentatus), Balkhash perch (Perca schrenkii), Triplophysa strauchii, T. labiata and Balkhash minnow (Rhynchocypris poljakowi). Other fish species were alien: common carp (Cyprinus carpio), spine,[which?] Oriental bream (Abramis brama orientalis), Aral barbel (Luciobarbus brachycephalus), Siberian dace (Leuciscus baicalensis), tench (Tinca tinca), European perch (Perca fluviatilis), catfish,[which?] Diptychus, Prussian carp (Carassius gibelio) and others. The fishery was focused on carp, perch, asp (Aspius aspius) and bream.
Abundant and dense reeds in the southern part of the lake, especially in the delta of Ili River, served as a haven for birds and animals. Changes in the water level led to the degradation of the delta – since 1970, its area decreased from 3,046 to 1,876 km2, reducing wetlands and riparian forests which were inhabited by birds and animals. Land development, application of pesticides, overgrazing and deforestation also contributed to the decrease in biodiversity. Of the 342 species of vertebrate, 22 are endangered and are listed in the Red Book of Kazakhstan. Forests of the Ili delta were inhabited by the rare (now probably extinct) Caspian tiger and its prey, wild boar. Around the 1940s, Canadian muskrat was brought to the Ili delta; it quickly acclimatized, feeding on Typha, and was trapped for fur, up to 1 million animals per year. However, recent changes in the water level destroyed its habitat, bringing the fur industry to a halt.
Balkhash is also the habitat of 120 types of bird, including cormorants, marbled teal, pheasants, golden eagle and great egret; 12 of those are endangered, including great white pelican, Dalmatian pelican, Eurasian spoonbill, whooper swan and white-tailed eagle.
Cities and economy
In 2005, 3.3 million people lived in the basin of the Lake Balkhash, including residents of Almaty – the largest city of Kazakhstan. The largest city on the lake is Balkhash with 66,724 inhabitants (2010). It is located on the northern shore and has a prominent mining and metallurgy plant. A large copper deposit was discovered in the area in 1928–1930 and is being developed in the villages north of the lake. Part of the motorway between Bishkek and Karaganda runs along the western shore of the lake. The western shore also hosts military installations built during the Soviet era, such as radar missile warning systems. The southern shore is almost unpopulated and has only a few villages. The nature and wild life of the lake attract tourists, and there are several resorts on the lake.
The economic importance of the lake is mostly in its fishing industry. Systematic breeding of fish began in 1930; the annual catch was 20 thousand tonnes in 1952, it increased to 30 thousands in the 1960s and included up to 70% of valuable species. However, by the 1990s production fell to 6,600 tonnes per year with only 49 tonnes of valuable breeds. The decline is attributed to several factors, including the halt of reproduction programs, poaching and decline in water level and quality.
In 1970, the 364-megawatt Kapshagay Hydroelectric Power Plant was built on the Ili River, drawing water out of the new Kapshagay Reservoir for irrigation. Ili's water is also extensively used upstream, in the Xinjiang province of China, for the cultivation of cotton. Currently, there is a project for an additional counter-regulatory dam 23 km downstream from the Kapchagay. The associated 49.5-MW Kerbulak Hydroelectric Power Plant will partially solve the problem of providing electricity to the southern areas of Kazakhstan and will serve as a buffer for daily and weekly fluctuations in the water level of Ili River.
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, mouth of Ili River and Kapchagay Reservoir. The main piers are Burylbaytal and Burlitobe. The ships 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 thousand tonnes of construction materials, 3,500 tonnes of ore, 45 tonnes of fish, 20 tonnes of melons and 3,500 passengers were transported on Balkhash. However, these values decreased by 2004 to 1000 passengers and 43 tonnes of fish. In 2004, the Balkhash fleet consisted of 87 vessels, including 7 passenger ships, 14 cargo barges and 15 tugboats. The government projects that by 2012, the transported volume in the Ili-Balkhash basin will reach 233 thousand tonnes of construction materials, at least 550 thousand tonnes of livestock and agriculture products and at least 53 tonnes of fish. Development of eco-tourism is expected to increase the passenger traffic to 6,000 people per year.
Environmental and political issues
There are serious concerns about the ecology of the lake, especially in the view of repeating the environmental disaster at the Aral Sea. Since 1970, the 39 km3 outflow of water to fill the Kapchagay Reservoir resulted in a 2/3 decrease in the supply to the lake from Ili River. The concomitant decrease in the level of the lake was approximately 15.6 cm/year, much larger than the natural decline in 1908–1946 (9.2 cm/year). The shallowing of Balkhash is especially evident in its western part. From 1972 till 2001, a small salt lake Alakol, located 8 km south of Balkhash, had practically disappeared and the southern part of the lake lost about 150 km2 of water surface. Of the 16 existing lake systems around the lake only five remain. The desertification process involved about 1/3 of the basin. 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.
Another factor affecting the ecology of the Ili-Balkhash basin is emissions due to mining and metallurgical processes, mostly at the Balkhash Mining and Metallurgy Plant operated by Kazakhmys. In the early 1990s, emission level was 280–320 thousand tonnes per year, depositing 76 tonnes of copper, 68 tonnes of zinc and 66 tonnes of lead on the surface of the lake. Since then, emission almost doubled. Contaminants are also brought from the dump sites by the dust storms.
In 2000, a major conference "Balkhash 2000" brought together environmental scientists from different countries, as well as representatives of business and government. The conference adopted a resolution and appeal to the Government of Kazakhstan and international organizations, suggesting new ways of managing the ecosystems of Alakol and Balkhash basins. At the 2005 International Environmental Forum devoted to Lake Balkhash, Kazakhmys announced that by 2006 it will restructure its processes, thereby reducing emissions by 80–90%.
Contamination of Balkhash originates not only locally, but is also brought by inflow of polluted water from China. China also consumes 14.5 km3 of water per year from Ili River, with a planned increase by 3.6 times. The current rate of the increase is 0.5–4 km3/year. In 2007, 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.