Analysis of land subsidence in the area of Neishabur city

Land subsidence is one of the dangers that have occurred in many parts of the world, especially in Iran, in recent years is the dangers caused by land subsidence. The most important cause of it is the illegal extraction of underground water sources and like other environmental hazards, it has created many problems and problems for the government's agricultural, civil, economic-social affairs. The city of Neishabur is located on the level of the Neishabur plain, which is one of the most important plains of Khorasan-Razavi province, which is facing the crisis of land subsidence. The radar interferometric technique is a powerful tool with millimeter accuracy in estimating subsidence using phase observations. In this research, the Sentinel 1A satellite data from 2017 to 2022 have been used in order to monitor the amount of subsidence that occurred in the area of Neishabur city, which is a small part of Neishabur plain. The results of radar interferometry showed that 18 cm of subsidence occurred in the studied area during the statistical period. In addition, to find out the cause of the subsidence, the information of piezometric wells in the area was collected and their changes during the period of 1370-1398 were examined. The amount of subsidence recorded for each period is 4 cm for 2017-2018 (1395-1396), 6 cm for 2018-2019 (1396-1397), 5 cm for 2019-2020 (1397-1398) and 2 cm. It was obtained for the period of 2020-2021 (1398-1399) and 1 cm for the period of 2021-2022 (1399-1400). In addition, the results of the research showed that there is a close relationship between the drop in the underground water level and areas with land subsidence in the area of Neishabur city.