Monitoring Ground Subsidence in New Orleans with Persistent Scatterers Interferometry

Ground subsidence and flooding are well publicized problems in the area of New Orleans, USA. Interferometric Synthetic Aperture Radar (InSAR) has been applied by various research groups to study the ground subsidence in the area as an international effort supported by the Canadian Space Agency (CSA), National Aeronautics and Space Administration (NASA) and United States Geological Survey (USGS). This paper presents some of the work carried out at the Hong Kong Polytechnic University in contribution to this effort. 23 Radarsat-1 images acquired over a 2.5-year period from December 2004 to March 2007 are used in the PS-InSAR processing. Over 23,000 PS points are identified in the area based on both the amplitude and the coherence variations in the sequence of images. A network of PS points is then formed and used in the PS solution. The LAMBDA method is used to facilitate the determination of the phase integer ambiguities. The average subsidence rate along the direction of the radar illumination determined is 2.1 mm per annum.