The Detection of Subsidence for Ground Stability Using Radar Interferometry Method with Permanent Scatterers (A Case Study: Shabestar-Sufian Plain)

Land subsidence is one of the natural hazards that occurs as a result of natural factors or a combination of these two factors, in the form of flooding. Monitoring land surface changes requires the use of precise techniques. In this regard, the radar interferometry technique with permanent dispersers with wide spatial coverage as well as high temporal and spatial resolution is one of the most accurate and cost-effective remote sensing techniques for monitoring and measuring the amount of displacement on the ground. In recent years, following climate change and successive droughts on the one hand, and the improper management of water resources, improper abstraction of groundwater and increasing growth of population, on the other hand, has led to land displacement - and subsidence, in particular - on the Shabestar-Sufi plain. Therefore, this study has evaluated and monitored the rate of land movement in this region by using the mentioned method and by processing Sentinel-1 images between 2016 and 2020. To study the changes in groundwater level in the region and to prepare a water drop map as well as the hydrograph of the observation wells in the region, water level data between 2001 and 2017 have been used. The results of the permanent dispersion method indicate the annual land displacement rate for the region from 2016 to 2020 in five periods - 8.54, -9.47, 8-9, -9.7 and -9.02 cm, respectively. Due to the lack of geodynamic and GPS stations in the region, validation of the results of the radar interferometry method was assessed by using piezometric well data and the predominance of groundwater level drop (4.7 m) in the region and hydrograph analysis of the aquifer unit, and by comparing the results of the previous research, and the accuracy of the results of the present study was confirmed.