Monitoring land subsidence due to geological and water resources factors using Differential Radar Interferometry method (Case Study: Arak city)

The prohibition of the entire area of the plains of the Markazi province and the impossibility of a new water withdrawal and occurrence of subsidence has caused the importance of monitoring of subsidence. On the other hand, the Differential Interferometry SAR (D-InSAR) is an efficient way to continuously, accurately and in a wide range monitor land subsidence. In this research, the D-InSAR method was used in the study of land subsidence in Arak city. 14 single-look complex images were obtained in the range of C-Band by EOLi-sa software. Ten processing steps were done by the SARscape software based on the four interferograms which had both the time and space criteria. On the other hand, the National Cartography Center has repeated the observations of the first-class network of the country for the city of Arak, located on the BHBT route (Borujerd-Salafchegan) in 1985 and 2004 and it measured 190mm ± 0.8mm / km of subsidence in 19 years. Based on four geocoded reflated unwrapped interferograms, the subsidence rate was calculated about one centimeter at year, for the central regions of Arak (around the Shohada Square of Arak). The urban areas had also almost identical subsidence rate. Therefore, the results of validation of the D-InSAR method using the observations of the National Cartography Center confirmed appropriate accuracy of the D-InSAR method. The results of this study showed the impact of geological and water resources factors on subsidence and the necessity of protecting water and soil resources in development projects in Arak city.