Groundwater over-exploitation and land subsidence in Tehran, Iran: A comprehensive assessment of causes and impacts

The rapid urbanisation and agricultural expansion in arid and semi-arid regions in Iran have significantly increased the demand for groundwater resources. Excessive groundwater extraction through deep wells has led to severe land subsidence, causing irreversible environmental and economic impacts. This study investigates land subsidence in the southwest Tehran plain. A review of previous research evaluates subsidence across different locations in the study area, using various methods such as levelling, Global Positioning System (GPS) techniques, Interferometric Synthetic Aperture Radar (InSAR), and Artificial Intelligence (AI). In addition, to examine the land subsidence trend, the D-InSAR technique was used to obtain land subsidence data in the southwestern part of the Tehran plain from 2017 to 2021. The findings indicate that the land subsidence trend increased from 2005 to 2014 and slightly decreased from 2015 to 2021. Furthermore, the results of analysis on the factors (precipitation, groundwater pumping, land use) influencing land subsidence show that the concentration of groundwater extraction wells is in agricultural areas, where land subsidence is also concentrated. According to the two measured sections, there is a direct relationship between land subsidence and groundwater extraction. The findings indicate that mismanagement of groundwater resources and unsustainable development practices are the primary drivers of subsidence in the study area. The study underscores the urgent need for sustainable development practices to address this escalating issue. Improved groundwater management strategies, including controlled extraction and water-saving measures, are critical to mitigating subsidence risks and preventing further damage to the region's infrastructure and environment.