Studying of Model of Stable Isotope Fractionation in Lake-Taking the Nam Co Lake as an Example

摘要

In recent 40 years, the mean temperature have increased by 0.7～0.8°C in source regions of Yangtze river and Yellow river, with the result that the local precipitation and melting amount of the snow increased. On the other hand, there is also a slight declining in evaporation in the river source area. But runoff of the Yangtze and Yellow Rivers has been decreasing each year. According to salt balance and water balance, the paper concluded that the leakage occurred on the bottom of Nam Co. The analysis of Hydrogen and Oxygen isotope further showed that seepage reached about 40% of the recharge. Therefore, it was inferred that the reason that runoff of the Yangtze and Yellow Rivers has been decreasing each year is leakage occurring in lakes in Tibetan plateau.