Subsidence of Critical Forbidden Plains (Study Area: Eshtehard Plain)

In recent decades, land subsidence has emerged as a significant geomorphological hazard and environmental crisis, resulting in extensive and often irreversible damage to the plains of Iran.The primary driver of this phenomenon is the ongoing water crisis.The Eshtehard Plain, a vital industrial and agricultural hub in Alborz Province, has been classified as a critical prohibited zone by the Ministry of Energy due to the severe decline in groundwater levels.Consequently, assessing the rate of subsidence and identifying its causes and influencing factors are essential for effective risk management.This study employed the Differential Radar Interferometry (D-InSAR) technique to analyze subsidence in the Eshtehard Plain, utilizing data from the Sentinel-1A satellite spanning the years 2017 to 2023.During this period, subsidence in the region ranged from -2.08 cm to -2.93 cm.The highest subsidence rate, approximately -2.93 cm, occurred between 2019 and 2020, while the lowest, approximately -2.08 cm, was observed between 2022 and 2023.Notably, subsidence rates exhibited an increasing trend from east to west and in the southern expanse of the plain.The maximum subsidence observed throughout all study periods was concentrated in the Eshtehard aquifer area, which encompasses a significant portion of farmland, villages, the city of Eshtehard, industrial towns (Kosar, Omid, and Eshtehard), agricultural lands, and the highest density of groundwater extraction wells.Hydrographic analysis and interpolation of piezometric well data further revealed a consistent decline in groundwater levels and an increase in water table depth in this area.Moreover, the correlation between land subsidence and changes in groundwater depth was statistically significant at the 95% confidence level, indicating that subsidence intensifies as groundwater levels decrease.The subsidence change profiles suggest a complex subsidence pattern within the study area, influenced by a combination of factors, including human activities (such as the intensity and type of land use, as well as excessive groundwater extraction), environmental conditions, geological characteristics (e.g., sediment composition, aquifer thickness, and bedrock position), and the rates of aquifer recharge and discharge.These findings underscore the urgent need for sustainable groundwater management and mitigation strategies to address the escalating subsidence crisis in the Eshtehard Plain.