Abstract:

The middle and upper reaches of Chaobai River alluvial fan supplies the most surface water and groundwater to Beijing, and it plays an important role in the urban water supplies. The water level decreased because of groundwater over-exploitation for years, and lowered up to 45 m in some areas. Total hardness of groundwater in the emergency water resource area increased at average rate of 2.6% annually. Contents of total hardness and nitrate exceed the criterion of Shilipu area in Miyun. This paper analyses the development and utilization of groundwater in Chaobai River alluvial fan, the changes in groundwater level and water quality, and effect of groundwater descending on water quality variations. It is concluded that over-exploitation is the main inducing factor of groundwater quality deterioration of the Chaobai River alluvial fan in the middle and upper reaches. Controlling surface water pollution and groundwater over-exploitation, then using south-to-north water to recharge groundwater and decreasing exploitation is a good way to restore water resources and environment.

Key words: over-exploitation, water level drop, recharge runoff and discharge condition, deterioration of water quality