Spatial-temporal characteristics of land subsidence corresponding to dynamic groundwater funnel in Beijing Municipality, China

Due to long-term over-exploitation of groundwater in Beijing Municipality, regional groundwater funnels have formed and land subsidence has been induced. By combining a groundwater monitoring network, GPS monitoring network data, radar satellite SAR data, GIS and other new technologies, a coupled process model based on the dynamic variation of groundwater and the deformation response of land subsidence has been established. The dynamic variation of groundwater funnels and the land subsidence response process were analyzed systematically in Beijing. Study results indicate that current groundwater funnel areas are distributed mainly in the southwest of Shunyi District, the northeast of Chaoyang District and the northwest of Tongzhou District, with an average decline rate of groundwater level of 2.66 m/yr and a maximum of 3.82 m/yr in the center of the funnels. Seasonal and interannual differences exist in the response model of land subsidence to groundwater funnels with uneven spatial and temporal distribution, where the maximum land subsidence rate was about -41.08 mm/yr and the area with a subsidence rate greater than 30 mm/yr was about 1637.29 km(2). Although a consistency was revealed to exist between a groundwater funnel and the spatial distribution characteristics of the corresponding land subsidence funnel, this consistency was not perfect. The results showed that the response model of land subsidence to the dynamic variation of groundwater was more revealing when combining conventional technologies with InSAR, GIS, GPS, providing a new strategy for environmental and hydrogeological research and a scientific basis for regional land subsidence control.