Seasonal displacements in upper-middle alluvial fan of Chaobai River, Beijing, China, observed by the permanent scatterers technique

Miyun-Huairou-Shunyi area, located on the upper-middle alluvial fan of Chaobai River, is the largest groundwater source region of Beijing, China. The study area is approximately equal to 479 km² and covers three counties. The area includes one ground-water sub-basin, named Chaobai River, which is filled with unconsolidated alluvial deposits that comprise the aquifer system. Groundwater constituted about 66% of the municipal water supply in this region. Groundwater withdrawals had not exceeded the natural recharge between 1989 and 1992. During a period of low runoff and extensive ground-water extractions from about 1993 to 2006, ground-water levels fell as much as 25.6 m. Extensive groundwater use in upper-middle alluvial fan of Chaobai River has resulted in the continual decline of piezometric levels associated with the environment consequences of land subsidence.