Establishment and data processing of high-precision city subsidence monitoring network by GPS surveying instead of leveling

The feasibility of monitoring the change of city settlement using GPS surveying instead of leveling is studied. A fiducial network and a monitoring network are established in Ningbo city. Two periods of GPS observation are completed. Some measures are taken during the observation in order to ensure to obtain the high-precise height component. The Saastamoinen model is adopted in the data processing of the dry component part of the tropospheric delay. The wet component change of the tropospheric delay is estimated by stochastic processes model. When Bernese software is used to process the data, the millimeter level precision of height measuring is achieved.