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Physical Geography of Northern Eurasia

Rivers, Lakes, Inland Seas, and Wetlands

Lakes

<<< The Caspian Sea | Physical Geography Index | The Issyk-Kul >>>

The Balkhash

Lake Balkhash is located in the vast Balkhash-Alakul depression and is a part of the system of faults of the Dzhungarsky Alatau, which also contains many other lakes (e.g., Alakol, Sysyk-Kul, and Lake Ebinur in China). Level fluctuations are typical of the Balkhash and the other lakes. The long-term fluctuations in the Balkhash have an amplitude of 12-14 m, with a minimum between the 5th and the 10th centuries and a maximum between the 13th and the 17th centuries, when water probably overflowed from the Alakol to the Balkhash. At present, levels of all lakes of the region, including the Balkhash, are in a declining phase of the cycle (Shaporenko, 1995). Against the background of these long-term fluctuations, shorter-term variations in the lake level occur in response to natural climatic variability.

Lake Balkhash extends from west to east for 600 km and there are considerable variations in the characteristics of the lake throughout its length. The large Sary-Isek peninsula divides the Balkhash into the western and the eastern sectors which have very different characteristics. About 80 per cent of the lake inflow is carried by the Hi river flowing into the western sector. Water salinity increases eastwards: in the western sector it varies between 1.04 and 1.56 g l-1 within the seasonal cycle, while in the eastern part it changes from 3.65 to 4.42 g l-1 (Shaporenko, 1995). The salt content of the Balkhash varies naturally in time in line with climatic conditions, changes in salt runoff, precipitation of carbonates, and losses in isolated pools. During the period of stable level before the 1960s, the total salt reserve of the Balkhash was falling because an increase in river runoff was accompanied by a decrease in salt runoff. However, the construction of the Kapchagay reservoir on the Hi has affected both the level and salinity of the lake. A rapid decrease in river runoff, caused by the filling of the Kapchagay reservoir and also by water abstractions for irrigation, has resulted in lowering of the lake level by approximately 2 m, a reduction in volume by 30 km3, and the growth of salinity especially in the western, most productive, sector of the lake (Ratkovich, 1993). Analysis of the Balkhash water balance has shown that if the natural regime had continued, the stable phase would have been replaced by a decline in 1975 (Skotselyas, 1989). The Balkhash environment, therefore, is now experiencing the combined effect of unfavourable natural and human factors. Numerous projects have been developed to prevent the decline of the western part of the Balkhash, focusing mainly on the construction of a dam separating the western and the eastern sectors (Shaporenko, 1995). However, the currently poor state of the regional economy does not allow these problems to be addressed.

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