Land Subsidence analysis in the Adjacency of Gas Pipelines Based on Radar Interferometry (A Case Study in Centeral Iran)

The land subsidence phenomenon as a geomorphic hazard has reached to a critical level in some parts of central Iran recently. The gradual and sudden land subsidence is influenced by natural and artificial parameters. The gradual land subsidence has a slow pace mainly due to the overextraction of underground water or oil resources. The continued land subsidence can, in the long period, deliver irreversible damages to buildings, roads, bridges and pipelines. The application of remote sensing technology in earth survey is very common due to the wide coverage of satellite imagery, the timeliness of images and its lower required budgets versus ground-based methods. One of the applications of remote sensing is to control the movement of the ground surface due to various factors such as earthquakes, landslides and land subsidences. In this research, two satellite images of SENTINEL1 from 2015 to 2017 and DEM of the mentioned region have been used. Special software was used for processing images by forming an interferogram and performing filtration, consequently the land subsidence was determined at this time interval. Investigations confirmed that the excessive use of underground water resources has led ro substantial amounts of land subsidence in Yazd province. Interferograms resulting from the processing of radar images showed the occurrence of land subsidence within the neighbourhood of gas distribution and transmission pipelines in specific at an average of 8 to 10 cm around several cities, in specific Ardakan and Meybod