Study of key driving factors in failure mechanisms of land subsidence and ground fissures in the southwest Tehran plain-Iran using SAR interferometry

Abstract Background Land subsidence (LS) in the southwestern plain of Tehran has a long history and represents a critical environmental challenge due to the strategic importance of Tehran as the political and economic capital of Iran. This study aims to investigate the mechanisms responsible for the development of surface deformation features and to evaluate the influence of major controlling factors on land subsidence processes. Field investigations were conducted to identify and characterize subsidence-related features and their spatial relationship with satellite-derived deformation patterns. Results Field surveys were performed at 369 locations covering nearly the entire study area, during which 49 land subsidence features, including point, linear, and polygonal features, were identified and documented. These features were evaluated against a seven-year cumulative land subsidence map (2017–2024) derived from Differential Interferometric Synthetic Aperture Radar (D-InSAR) analysis. The influence of major contributing factors, including land use, fault zones, groundwater withdrawal wells, groundwater extraction intensity, clay layer thickness, and bedrock elevation, was systematically assessed. The results indicate that groundwater extraction through withdrawal wells (73%) and land use (65%) are the dominant factors controlling the occurrence of subsidence features. Clay layer thickness (57%), fault zones (41%), and bedrock elevation (16%) were identified as additional factors with varying degrees of influence. Conclusions The findings demonstrate that anthropogenic groundwater exploitation is the primary driver of land subsidence feature development in the southwestern Tehran plain, while geological and geomorphological conditions regulate their spatial distribution. Considering the high subsidence rates observed in the region, an increase in the occurrence and spatial clustering of subsidence-related features, including sinkholes, cracks, and fissures, is expected in the future, particularly near buried fault zones and areas with heterogeneous bedrock topography. Irregular bedrock morphology associated with lithological variations can amplify surface deformation and facilitate the initiation and propagation of ground failures.