Revealing Land Subsidence in Heris Plain Using Radar Images and SBAS, PSI Method

Landslides are one of the most important environmental hazards to be considered in the Harris Plain area. The phenomenon of subsidence in recent decades has created many problems for agricultural lands, residential areas, roads and water supply canals in some parts of the country. In order to analyze the time series of surface displacement, a short baseline algorithm called SBAS was used. Subsidence time series analysis was performed using 6 interferograms calculated from 21 radar images of Sentinel1 satellite over a period of 4 years (2016-2019). It is an optimal attenuation factor that reduces atmospheric noise, phase recovery error, and orbital effects; in other words, it reduced atmospheric effects using the atmospheric model to optimally maintain nonlinear signals. The results of the time series analysis showed that the region is continuously subsiding. PSI method was also applied to estimate subsidence and compare it with SBAS method, which showed the superiority of SBAS method with PSI method in this study. In this research, using land radar images of Sentinel 1 and also images of Sentinel 2, the land subsidence in Harris plain has been estimated. The land uses in the plain were extracted from Sentinel 2 images and adapted to the results of radar images to investigate the relationship between land subsidence and each of the land uses in the Harris Plain. The results of two methods of estimating land subsidence showed the amount of land displacement (0 to 15) cm per year. The results of depth analysis of piezometric wells also show a strong relationship between subsidence and the depth of water wells in the region.