Land subsidence and groundwater storage investigation with multi sensor and extended Kalman filter

More than 90% of Iran's provinces are facing land subsidence due to uncontrolled groundwater extraction. In 2016, a sinkhole was created in Eij region of Estahban city. In this study, interferometric synthetic aperture radar (InSAR) from 2014 to 2020, gravity recovery and climate experiment (GRACE) and GRACE-Follow on (GRACE -FO) from 2002 to 2020 and piezometric well (PW) from 1993 to 2015 were used to study subsidence and groundwater storage (GWS). Various scenarios have been considered for GWS signal reconstruction with an extended Kalman filter (EKF). The scenario that has the most correlation with the observations of other sensors was selected as the best scenario. GWS has a downward trend of 0.263 gigaton/year. The maximum Eij subsi-dence is 16 cm/year and the subsidence around the sinkhole is evaluated at 8 cm/year. The PW has a decreasing linear trend of 1.91 m/year. All 3 sensors have an average correlation of 0.81. Continuous wavelet transform was used to determine InSAR, GRACE and PW periods. The period of about 3 years PW is compatible with GRACE. The detected periods of InSAR and GRACE are well compatible.

Automated summary

More than 90% of Iran's provinces are experiencing land subsidence due to uncontrolled groundwater extraction. The study used various sensors to analyze subsidence and groundwater storage, finding a downward trend in groundwater storage and significant subsidence in certain areas.