Abstract:

The aim of this paper is to analyze the spatial and temporal changes of renewability of groundwater in Beijing, which is great important for the sustainable utilization and management of groundwater resources. The recharge volume, renewing cycle, renewal rate, and recharge rate of groundwater in the Beijing Plain, especially in the mining aquifers, were calculated using groundwater table dynamic equilibrium method. The renewability of groundwater and changes of its spatiotemporal were further evaluated. The study results show that, under natural conditions, the renewability of groundwater is generally strong with a decreasing trend from the piedmont to the central plain. Secondly, the aquifers in this study have favorable boundary conditions for groundwater recharge from exterior and excellent water bearing conditions. The amount of precipitation is the bottleneck factor influencing the renewability of groundwater. Thirdly, the renewability of groundwater in investigated area and all the sub areas have decreased clearly with mean annual groundwater recharge rate during 2001-2008 (0.28 m/a) decreasing by 35.6% compared with that in 1981-2000. Lastly, the mean groundwater level in 2008 is 19.73 m which is deeper than that in natural conditions (in and before 1960s). The total loss of groundwater volume has reached 101×10⁸ m³ since 2008 (accounting for 18% of the total volume of groundwater in the mining aquifers) because the groundwater exploitation intensity is always exceeding the renewability of groundwater recently. The above evidences show that the issue of groundwater sustainable supply is serious in Beijing under the impacts of climate change and human activities.

Key words: Beijing, dynamic equilibrium, renewing cycle, recharge rate, groundwater, renewability