Long-term investigation of subsidence rate and its environmental effects using the InSAR technique and geospatial analyses

Abstract

Herein, we examined the subsidence occurring over two main plains for agricultural activities in Qom province in Iran using interferometric synthetic aperture radar (InSAR). ENVISAT-ASAR images from 2003 to 2010 and Sentinel-1A images from 2014 to 2019 were used to produce interferograms and mean velocity maps of subsidence in the line of sight (LOS) direction. Using the analyses in geospatial information science (GIS), the spatial correlations between areas with subsidence and water level drop and agricultural land-uses were explored. The results showed the mean velocity map which revealed 35 and 28 mm/yr of deformation going away in the LOS direction in Jafarabad and Qanvat plains, respectively, between 2003 and 2010 and higher subsidence rates between 2014 and 2019. Moreover, maximum subsidence occurred in the places that had not only a larger water level decline, but also a greater thickness of fine-grained sediments. Finally, the environmental effect of subsidence on the ground, infrastructures and water salinity was examined.

Keywords:

• Subsidence
• environmental impact
• InSAR
• geospatial analyses
• geospatial information science
• water extraction

Acknowledgments

We would like to express appreciation to the European Space Agency (ESA) for providing SAR images (ENVISAT and Sentinel-1). We also thank the National Cartography Center of Iran for providing us with precise levelling data. Some of the figures are generated with the public Generic Mapping Tools (GMT) software (Wessel & Smith 1995). We used the SRTM DEM derived from the USGS/NASA SRTM data in InSAR processing. We processed the ENVISAT images using the freely available StaMPS/MTI software package, developed by the University of Leeds (Hooper 2008). The Sentinel-1 images were processed using NSBAS (Doin et al. 2011). Sentinel data were provided by the ESA.

Disclosure statement

No potential conflict of interest was reported by the authors.