关键词: 博斯腾湖, 开都河, 水矿化度, 大湖, 孔雀河, 小湖区, 控制途径, 盐化, 盐量, 农田排水

Abstract: The Bositeng Lake is the biggest fresh water lake in the inland region of China. The area of the lake is 980 square kilometres, its water volume-7.73 cubic kilometres, its average water depth-7.7 metres, and the average altitude of the lake level-1047.59 metres. The Kaidy River is the main source of its water supply.Under the influence of human activities, the mineralization of the lake water has been constantly increasing. In the year 1958 its mineralization was less than 0.4 g/1, while in 1975 it rose to 1.5 g/1, and in 1980 to 1.8 g/l. The average annual increase was 0.06 g/l, which is quite amazing. The hydrochemical types of the lake water also had been changed from HCO₃-Na and HCO₃-Xa-Mg in 1958 to S0₄-CI-Na-Mg and SO₄-Cl-HCO₃-Na-Mg in 1975. By 1980, it changed further to Cl-SO₄-Na-Mg and Cl-SO₄-HCO₃-Na-Mg type.The cause of the increase in mineralization of the lake water, on one hand, is due to the considerable flow of mineralized farm drainage water into the lake. According to investigation data, the amount of the drainage reaches 0.265 cubic kilometres per year, and salt carried into the lake amounts 637 thousand tons. On the other hand, because the Kaidy River has partly changed its course, large amounts of its water flow direct into the Konche River, without travelling through the Bositeng Lake. As a result, the entering fresh water has decreased from 2.3 cubic kilometres in 1958 to 1.26 cubic kilometres at present, and therefore, the lake water circulation has been hindered. The salt carried into the lake is more than that out of the lake, hence giving rise to the salt accumulation and increase in water mineralization.In order to prevent the lake water from the increase in mineralization, it is neces-sary to control and reduce the quantity of salt delivering into the lake by farm drai-nage water, to accelerate the lake water circulation by recovering the quantity of fresh water flowing into the lake to the previous level, and to conduct a regular moni-toring of water quality.