Investigating the subsidence of Mashhad using radar interferometry
sayyad asghari saraskanroud
1
(
Mohaghegh Ardabili University, Faculty Literature of Humanities, Department of geography
)
zahra nazari gazik
2
(
Ph.D. student, Geomorphology, Faculty of Social Sciences, Mohaghegh Ardabili University
)
Keywords: interferometry, subsidence, Sentinel 1, Mashhad city, drop in underground water level,
Abstract :
. The radar interferometric technique is a powerful tool in estimating subsidence with accuracy within mm using phase observations. In this article, Sentinel 1A satellite data from 2017 to 2021 have been used in order to monitor the subsidence that happened in Mashhad. Also, Sentinel 2 images of 2020 were used to monitor rainfed and irrigated crops in the region. The results of the radar interferometric studies showed that during the statistical period, 44 cm of subsidence occurred in the studied area. Further, in order to find the cause of 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 was 6 cm for 2017-2018, 12 cm for 2018-2019, 15 cm for 2019-2020 and 11 cm for 2020-2021. According to the results, the underground water level in the areas with land subsidence has been accompanied by a drop. Especially in the villages of Mehdi Abad, Shahr Danesh, Mashhad Qoli, etc., which have the highest drop in the underground water level and are also in the risk zone of high subsidence. One of the main reasons for land subsidence in the study area is the excessive extraction of underground water resources.