Monitoring land subsidence and determining its relationship with groundwater abstraction using PS-InSAR method, Case study of Rafsanjan plain, Iran

The issue of subsidence is one of the serious problems in the plains of Iran. Rafsanjan plain is also prone to this danger due to the high level of groundwater abstraction. In this study, an attempt has been made to study the extent and process of subsidence expansion over a period of time. For this purpose, ASAR and SENTINEL 1 radar images related to 3 four-year periods were prepared from Anar plain and PS-InSAR method was used to determine the amount of subsidence and its monitoring. The results show that between 2008 to 2012, the southern parts of the plain had an average subsidence of 10 cm per year, and between 2012 to 2016, the subsidence rate increased to 11.7 cm per year while between 2016 to 2020, the subsidence rate has increased more sharply and has reached 18.2 cm per year. Also, during these years, the area of subsidence has increased from 5,000 to 15,000 hectares and the subsidence trend has expanded to the northern parts of the plain. By preparing a map of groundwater level drop related to the last decade of the studied plain, it is determined that the areas that have subsided are completely consistent with the areas with more water table drop. Therefore, due to the increase in the cultivation of pistachio orchards in recent years and as a result of more use of groundwater, the rate of subsidence has increased.