Environmental change in Bosten Lake and its relation with the oasis reclamation in Yanqi Basin

The paper analyzes the environmental change in Bosten Lake since 1958 and points out the reasons in the context of both natural environment and human activities. In the last 40 years, the impacts of the natural factors on water level change is more than the contribution of human activities in the water level change; however, the water quality change is mainly influenced by human activities. The fact that Bosten Lake has become a salt water lake rapidly from a fresh water one is related to special geographical location of the Lake, but it mainly resulted from the reduction of Bosten Lake input amount and a great quantity of water from farmaland drained into the Lake, especially the latter. Farmland drainage is not only the direct reason leading to the increase in the mineral concentration of Bosten Lake, but also a key effect on the hydrochemical change and controls the formation of hydrochemical type of Bosten Lake water. Based on the above analyses, the paper further discusses the mechanism of the interaction between the environmental change of Bosten Lake and the environmental change of oasis in Yanqi Basin, and points out that over the last 10 years, the environmental change of oasis in Yanqi Basin has been sustainable. However, the sustainable development of the whole Basin's Yanqi environment depends largely on the reclamation scale of oasis. The appropriate scale of oasis reclamation in Yanqi Basin ensures the sustainable development of environment of both the Lake and oasis in the Basin.