Land subsidence in Isfahan metropolitan and its relationship with geological and geomorphological settings revealed by Sentinel-1A InSAR observations

Recent reports from Isfahan, Iran, have proclaimed cases of land subsidence arising from persistence of drought events and groundwater overexploitation. In this light, the present study attempts to conduct an PS-InSAR analysis of subsidence events using the Sentinel-1A Synthetic Aperture Radar imagery technique, in order to develop a subsidence map of the target study region, covering the period from October 16, 2014 to November 22, 2019 as well as to investigate its relation to geological/geomorphological factors. Toward this end, the methodology proceeds to detect land subsidence phenomenon across the Isfahan Metropolitan area, situated on the Zayande-Rud River Terrace (ZRT) and Isfahan Alluvium Plain (IAP). A total of 198 Sentinel images were used to derive deformation specifics observed throughout ZRT & IAP by dint of incorporating ascending and descending passes of the InSAR technique. As maintained by spatial and temporal variation maps of surface deformations in the urban regions of Isfahan, ZRT & IAP have undergone various orders of subsidence throughout the observation period, at an estimated rate of - 5 to -100 mm/year. Overall, land subsidence appears to increase from south towards the northern, northeastern, and eastern sectors of Isfahan Metropolitan, while the southern sectors are nearly a stable area. This study indicates that the spatial subsidence pattern during the study period corresponds closely to the spatial distribution of ZRT & IAP in the Isfahan Metropolitan area.