INTEGRATION OF LEVELING AND INSAR DATA FOR LAND SUBSIDENCE MONITORING

Leveling surveys have traditionally been used for the geodetic monitoring of land subsidence. Although optical leveling allows for the detection of very small deformations, it is rather expensive and time-consuming. Because of the high temporal and spatial resolution versus relatively low costs, the interferometric use of Synthetic Aperture Radar (InSAR) is in principal a promising supplement for precise deformation monitoring. In this paper an integrated approach is described for the adjustment and testing of height differences from both leveling and InSAR data. This approach is restricted to subsidence due to gas or oil extraction, for which a smooth spatio-temporal subsidence bowl may be assumed and residual subsidence can be stochastically modeled. Test computations show that the velocity, shape and location of an isolated subsidence bowl due to oil extraction can be in good agreement when estimated from either leveling observations only or from combined leveling/InSAR observations. In such an integrated approach the number of leveling observations can be significantly reduced. Nevertheless, leveling data remain necessary, since the availability and quality of InSAR data cannot always be guaranteed yet. 1.