Beijing is a city of severe water shortage. The groundwater plays a key role in the water supply. However, the groundwater level has been gradually descending due to extensive pumping in consecutive drought years. How to satisfy the water demand and recover the groundwater level is an urgent work. With the implementation of the South to North Water Transfer Project, an opportunity has been provided for restoration of groundwater under over exploitation. On the basis of hydrogeology conditions of the Beijing plain, as well as the high-performance parallel computing platforms, a groundwater flow numerical model was established. And dynamic monitoring data of groundwater levels were used to calibrate the numerical model. The calculation results fit well with the measured data in the calibrated model. Therefore, the calibrated model can be used to predict the dynamic change of groundwater levels in the Beijing plain. The results show that several obvious depression cones of groundwater have been formed because of the rapid decline of groundwater levels in the Beijing plain in recent years. After the implementation of the South to North Water Transfer project and due to the restrictions on groundwater exploitation, the area of cone of depression will be reduced to different degrees, the central water level of depression cone will increase, and some cones of depression around wellhead will disappear. It is a benefit to relieve water shortage and control the development of land subsidence and the deterioration of the ecological environment.

Reclaimed water is useful for replenishing dried up rivers in North China, although changes in water quality could be an issue. Therefore, it is essential to understand the spatio-temporal variation and the controlling factors of water quality. Samples of Yongding River water were collected seasonally, and 24 water quality parameters were analyzed in 2015. All waters were alkaline, and nitrate-nitrogen was the main form of nitrogen, while phosphorus was mostly below detection level. The water quality parameters varied in time and space. Cluster analysis showed a distinct difference between winter and the other seasons and between the natural river section and the section with reclaimed water. Based on the analysis of Gibbs plots, principal component analysis, and ionic relationships, the water chemistry was controlled by dissolution of rocks in natural river section, the quality of replenished water, the effects of dilution, and the reaction of aqueous chemistry in the reclaimed water section. The positive oxidation environment in most of the river water was conducive to the formation of nitrate-nitrogen by nitrification, and not conducive to denitrification.

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