RELATIONSHIP BETWEEN GROUNDWATER AND LAKES IN BADAIN JARAN DESERT, CHINA

Badain Jaran desert has attracted a lot of concerns due to typical landscape of sand dunes and lakes. Groundwater supports the water demand for strong evaporation loss from the lakes and the groundwater circulation mode has been affected by the group of lakes. At regional scale, the hydrogeological characteristics of Badain Jaran desert are controlled by the Mesozoic Yingen-Ejina Basin. It is indicated by hydrogeological survey and synthetic observations around typical lakes that the annual evaporation rate of the lake water can be as large as 1800-2000 mm and the formation of these salt lakes elapsed at least 1000 years. Both shallow groundwater originated from local precipitation infiltration and deep groundwater transferred from neighborhood area of the desert contribute to the lake water. Groundwater flow generally towards west from east but is disturbed by the group of lakes so that a nested structure of local and regional flow systems is exhibited. The lakes closer to the east edge of the desert are more strongly depended on recharge of regional later flow of groundwater, otherwise, the lakes tend to be dominated by shallow groundwater discharge. The total lateral flow rate from the east edge of the desert, according to a brief estimation with regional hydraulic gradient, would be (0.5~1.0)×10⁸ m³/a. In considering of the total evaporation loss from the lakes, the excess discharge of groundwater towards the Ejina Basin would be (0.2~0.8)×10⁸ m³/a which is much less than the streamflow of Heihe River at the Zhengyi gorge.