Aly, Mohamed Hassan (2006-08). Radar interferometry for monitoring land subsidence and coastal change in the Nile Delta, Egypt. Doctoral Dissertation. Thesis uri icon


  • Land subsidence and coastal erosion are worldwide problems, particularly in
    densely populated deltas. The Nile Delta is no exception. Currently, it is undergoing land
    subsidence and is simultaneously experiencing retreat of its coastline. The impacts of
    these long-term interrelated geomorphic problems are heightened by the economic,
    social and historical importance of the delta to Egypt. Unfortunately, the current
    measures of the rates of subsidence and coastal erosion in the delta are rough estimates
    at best. Sustainable development of the delta requires accurate and detailed spatial and
    temporal measures of subsidence and coastal retreat rates.
    Radar interferometry is a unique remote sensing approach that can be used to
    map topography with 1 m vertical accuracy and measure surface deformation with 1 mm
    level accuracy. Radar interferometry has been employed in this dissertation to measure
    urban subsidence and coastal change in the Nile Delta. Synthetic Aperture Radar (SAR)
    data of 5.66 cm wavelength acquired by the European Radar Satellites (ERS-1 and ERS-
    2) spanning eight years (1993-2000) have been used in this investigation. The ERS data have been selected because the spatial and temporal coverage, as well as the short
    wavelength, are appropriate to measure the slow rate of subsidence in the delta. The ERS
    tandem coherence images are also appropriate for coastal change detection.
    The magnitude and pattern of subsidence are detected and measured using
    Permanent Scatterer interferometry. The measured rates of subsidence in greater Cairo,
    Mansura, and Mahala are 7, 9, and 5 mm yr-1, respectively. Areas of erosion and
    accretion in the eastern side of the delta are detected using the ERS tandem coherence
    and the ERS amplitude images. The average measured rates of erosion and accretion are
    -9.57 and +5.44 m yr-1, respectively. These measured rates pose an urgent need of
    regular monitoring of subsidence and coastline retreat in the delta.
    This study highlighted the feasibility of applying Permanent Scatterer
    interferometry in inappropriate environment for conventional SAR interferometry. The
    study addressed possibilities and limitations for successful use of SAR interferometry
    within the densely vegetated delta and introduced alternative strategies for further
    improvement of SAR interferometric measurements in the delta.

publication date

  • August 2006