Land subsidence induced by groundwater pumping, monitored by D-InSAR and field data in the Toluca Valley, Mexico

Excessive groundwater pumping from compressible aquifers leads to land subsidence, potentially causing significant damage to buildings and infrastructure. Differential interferometry is applied to synthetic aperture radar (SAR) images (D-InSAR) of the Toluca Valley, Mexico, with the aim of measuring and monitoring land subsidence. D-InSAR results are verified with field data. Additionally, the different sensors are compared and contrasted. A total of 30 SAR images from various C-band sensors with dates ranging from December 1995 to May 2008 were used. Forty-four D-InSAR pairs were generated with 31 usable interferograms. ENVISAT ASAR generally had shorter baselines than RADARSAT-1, and thus more usable interferograms. Verifying InSAR results involved installing and taking measurements from two extensometer systems. The compressible clays compact in a relatively linear fashion, where varying compaction rates are a function of drawdown and geologic properties. The total maximum subsidence for a point location in the valley between November 2003 and May 2008 is approximately 40 cm. It is estimated that the maximum total subsidence since 1962 is over 2.0 m.