西藏羊卓雍湖水环境变化探索研究

ON THE CHANGE OF WATER ENVIRONMENT IN YANGZHUOYONG LAKE, TIBET

本文对西藏羊卓雍湖水环境现状和变化趋势进行了研究。用水量平衡方程和零维水质模型定量计算了该湖水利资源开发后水量和矿化度的变化,结果表明,湖水矿化度在水平和垂直方向的变化不大;67年后,湖水面积减少121.4km^2,年入湖水量比蒸发量大1.8l亿m^3,可供继续发电,水量达到新的平衡;湖泊水质逐渐淡化,700年后湖水矿化度将达平衡浓度。保持现状不开发羊湖水资源,湖泊水质将继续咸化。

The Yangzhuoyong Lake, a big enclosed type lake in Tibet, has a water capacity of 14300 million m3. The amount of water entered the lake equals basically to that evaporated and the water level is relatively stable. The mineralization of the lake water is about 1 900 mg/L now. The lake water can be exploited for generating electricity by using the potential energy of water level between Yangzhuoyong Lake and Yarluzangbu River. In this paper, the changes of the water capacity and mineralization after exploiting the lake water resource are calculated quantitatively with the balance equation of water capacity and zero-dimensional model of water quality. The result shows that the change of mineralization is not remarkable, but the lake area will decrease 121.4 km3 after 67 years. So the water entered the lake is 181 million m3 more than the water evaported each year. These surplus water can be used for generating electricity. The water will gradually desalinate and the mineralization will tend to equilibrium concentration after 700 years. If the lake is not exploited, the water quality will be continually saltified.