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Neyshabour Subsidence Monitoring using Interferometric SAR Technique

Maryam Dehghani(1), Mohammad Javad Valadan Zouj(1) and Sassan Saatchi(2)

(1) K. N. Toosi University of Technology, Geological Survey of Iran, Meraj St., Azadi Sq.,, 13899, Iran
(2) UCLA Center for Tropical Research, los angeles, , 951496, United States

Abstract

A large agricultural area around the city of Neyshabour located in the northeast of Iran is subject to the land subsidence. In order to map the extent of the subsidence and determine its pattern, the interferometric SAR (InSAR) approach was used. 14 ENVISAT ASAR images were used in order to generate the interferograms. Time series analysis using a significant number of interferograms enabled us to estimate the mean displacement velocity map. Smoothing constraint entered into the time series algorithm reduced the various existing errors such as orbital, unwrapping error and noise. The estimated surface deformation rate reaches to 25 (cm/yr.) which can be a cause for concern. The time series analysis results were compared to the continuous GPS measurements in one station. The time series results show a great agreement with GPS measurements. Moreover, the piezometric information exhibits a considerable decline in water table. The correspondence between surface deformation rate and water table decline shows that the subsidence occurrence is due to the excess groundwater withdrawal.

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry