29.06.2016: Beijing is one of the five most water-stressed cities in the world. Due to extensive over-exploitation of groundwater Beijing region is suffering from land subsidence since 1935. The interpretation of satellite imagery for the years 2003 to 2011, which was done in a study of an international team of scientists with the participation of the GFZ, now shows that parts of Beijing, especially the financial district of the city, subside per year by about 10 centimeters.

Beijing is located within a dry plain where groundwater accumulated over thousands of years which is used nowadays as the major water source. Due to the extensive use of the groundwater resources by legal and illegal wells the underground dries out and subsequently subsidence happens. The land subsidence is seen a severe geohazard. Since the spatial pattern of subsidence is not distributed homogenously there is a high risk for buildings and infrastructure.

Knowing such a risk is essential for the development of remediation measures. With the analysis of the Interferometric Synthetic Aperture Radar (InSAR) data land subsidence can be monitored precisely over wide regions with high spatial-temporal resolutions. Similarly it is possible identify the main triggering factors of land subsidence in the form of groundwater level, geological faults, and soil type. Especially it was shown that land subsidence rate increases as the distance to the normal pumping wells decreases. (ak)

Chen, M., Tomás, R., Li, Z., Motagh, M., Li, T., Hu, L., Gong, H., Li, X., Yu, J., Gong, X., 2016. Imaging Land Subsidence Induced by Groundwater Extraction in Beijing (China) Using Satellite Radar Interferometry. Remote Sensing 8 (6), 468, doi: 10.3390/rs8060468