In the heart of Iran’s Heris Plain, a silent and invisible threat has been steadily reshaping the landscape, with significant implications for agriculture, infrastructure, and the energy sector. Land subsidence, caused primarily by excessive groundwater extraction, has been a growing concern, and a team of researchers led by Asadollah Hejazi from the University of Tehran has been utilizing advanced radar technology to monitor and understand this phenomenon.
Using a method called SBAS (Small Baseline Subset), the team analyzed 21 radar images from the Sentinel-1 satellite, captured over a four-year period from 2016 to 2019. This technique, which is part of a broader field known as radar interferometry, allows scientists to detect and measure subtle changes in the Earth’s surface. “The SBAS method is particularly effective because it reduces atmospheric noise and orbital effects, providing a clearer picture of the subsidence,” explains Hejazi.
The results of their study, published in the journal ‘Geography and Environmental Sustainability’ (جغرافیا و پایداری محیط), revealed a stark reality: the Heris Plain is continuously subsiding. The central part of the plain experienced the highest rate of subsidence, with some areas sinking up to 16 cm per year. “The maximum amount of subsidence is related to rangelands, where groundwater extraction is most intense,” notes Hejazi.
The implications for the energy sector are significant. Groundwater is a critical resource for both agricultural and industrial activities, including energy production. As subsidence continues, it can lead to infrastructure damage, increased flooding risks, and reduced water availability. “There is a direct and strong relationship between subsidence and groundwater abstraction,” says Hejazi. “This finding underscores the need for sustainable water management practices in the region.”
The study also compared the SBAS method with another technique called PSI (Persistent Scatterer Interferometry). While both methods provided valuable insights, SBAS proved to be more reliable in this context due to its lower standard deviation and better correlation with well water level changes. “The SBAS method provides a wide and continuous coverage of the area, making it possible to determine the extent of subsidence-affected regions,” Hejazi explains.
This research not only highlights the urgent need for sustainable water management but also demonstrates the power of advanced radar technology in monitoring and mitigating environmental hazards. As the energy sector continues to rely on groundwater, understanding and addressing subsidence will be crucial for ensuring long-term sustainability and resilience.
The findings of this study could shape future developments in the field by promoting the adoption of advanced monitoring techniques and encouraging more sustainable water management practices. As Hejazi puts it, “By leveraging technology and data, we can make informed decisions that balance the needs of industry, agriculture, and the environment.”