Change and cause analysis of water resources in Fengtai district of Beijing in recent 61a (from 1956 to 2016)

The calculation of water resources is the fundamental basis for legitimate utilization, effective protection, optimal configuration and optimal dispatch of water resources. Affected by climate change, economic development, and population expansion, the amount of water resources in Fengtai district, one of the central urban areas of Beijing, has undergone major changes. By comparing the results of the second investigation and evaluation of water resources (1956-1998), the paper analyzes the dynamic changes and causes of surface water resources, ground water resources and total water resources in Fengtai district in recent 61a (1956-2016). The results show that the surface water resources of Fengtai district in recent 61a is 37.978 million m3, which is 2.572 million m3 less than the previous investigation; the ground water resources is 92.959 million m3, a decrease of 13.848 million m3; the total water resources is 104.981 million m3, which is 13.830 million m3 less than the previous investigation. The gradual reduction of regional atmospheric precipitation is the main cause of the decline in surface runoff and rainfall infiltration recharge. At the same time, the continuous water-cutting of Yongding River (the biggest inflow river in Fengtai) since 2000 and the anti-seepage project implemented in 2010 further reduced the infiltration of river infiltration .