PRELIMINARY RESULTS FROM INSAR MEASUREMENTS OF SUBSIDENCE IN MANSOURA CITY, EGYPT

A major debate has evolved in the last decade concerning whether or not the land surface of the Nile Delta is subsiding. The debate is certainly problematic in light of the fact that current measures of subsidence in the delta are rough estimates at best. In this study, conventional Differential Synthetic Aperture Radar Interferometry (DInSAR) and Permanent Scatterers (PS) techniques were applied to detect and measure land subsidence in Mansoura City in the eastern part of the Nile Delta. DInSAR measurement of land subsidence in the delta poses a challenge as a result of vegetation, soil moisture content and water vapor. Interferograms were found completely decorrelated over densely vegetated areas and noisy over urban areas. To overcome limitations in DInSAR, interferometric measurements were carried out on stable reflectors by exploiting a long temporal series of thirty nine descending interferometric scenes acquired by the European Remote Sensing Satellites (ERS1&2) during the 1993-2000 period. Land subsidence measurements in Mansoura City as well as in other cities in the delta will provide a broad understanding of the subsidence phenomenon in the delta. Accurate measure and detection of the subsidence magnitude and its pattern in the delta will be helpful to mitigate the impact of geomorphic hazards associated with land subsidence in the Nile River Delta.