Surface subsidence monitoring with radar interference technique (study area: Meshgin plain)

Land subsidence is a phenomenon that has been on the rise in recent decades in most countries around the world, especially in third world countries such as Iran. in Iran, most land subsidence is related to agriculture and the uncontrolled extraction of groundwater. This phenomenon can cause irreparable damage to the affected areas if not properly managed. Identifying subsidence areas and estimating its rate will certainly play a significant role in managing the control of this phenomenon. One of the best ways to detect a subsidence phenomenon is to use a radar differential interference technique. Meshgin plain is one of the most important plains in Ardabil province in terms of agricultural development, which in recent years has faced the phenomenon of land subsidence due to uncontrolled extraction of groundwater resources. Data collected by piezometric wells at the plain level show an average drop in static level over a 14-year period of 23.75 meters. The consequences of this drop in groundwater levels have led to subsidence and cracks and crevices in parts of the plain. Declining water level and subsequent increase in effective stress is the main reason for the subsidence of the Meshgin plain. In this study, in order to determine the affected area and finally estimate the amount of subsidence, radar interference method was used as a reliable method to measure land surface changes with very high accuracy, wide coverage and high spatial resolution. The maximum subsidence rate was calculated using the radar images of the Sentinel 1 satellite in the period from 2019/08 to2020/04 – 9.35cm. From the results of radar interference, it was determined that the subsidence extends from southeast to southwest of the plain.