Subsidence monitoring of Yazd Abarkuh plain using radar interferometry technique based on persistent scatterers

Radar interferometry technique is an efficient tool to study changes in the Earth's crust. The method is based on the phase difference between two image pairs at different time intervals. In this research, subsidence of Abarkuh plain, Yazd province investigated. The subsidence is actually the lowering of the Earth's surface due to the natural and human activities. Excessive extraction of underground resources, especially water, is a main cause of subsidence in many plains in Iran. Hydrological studies in this area show a groundwater level drop of 0.6 meters per year. According to the geological studies, karst developments and dispersive clay soils are two causes of subsidence. By the radar interferometry technique over a period of 2003 to 2005 using 12 Envisat satellite images, the average subsidence rate in the region was estimated. In Abarkouh, maximum subsidence rate is 2 to 3 cm/year and in Mehrdasht area 5 cm/year. Accurate alignment studies have been used for the accuracy of the calculations between 1985 and 2001, which are in agreement with the results obtained by radar interferometry. The reasons for this discrepancy are the inconsistency between two available data and the radar interferometry error.