"Assessment of Land Subsidence in Asadabad Plain of Hamadan and its Hazards"

Abstract

The subsidence is one of the hazards that has posed a significant threat to many plains in the country in recent years. Asadabad Plain in Hamedan province is among those plains with a high potential for subsidence due to its hydro climatic conditions and geomorphology. Because of the importance of this issue, in this research the subsidence status of Asadabad Plain has been assessed and unlike many previous researches, the role of human factors in its occurrence has been analyzed. To do so, Sentinel-1 radar images, Landsat 5 and  8 satellite images, statistical information related to piezo metric wells in the region, and digital elevation layers were used as the primary data sources. Using the SBAS time series method, a subsidence map of the area from 2015 to 2022 was generated, followed by an analysis of the impact of groundwater depletion and land-use changes on subsidence. The results indicate subsidence ranging from 132 to 704 millimeters in Asadabad Plain during 2015 to 2022, with the highest subsidence occurring in the central regions of the plain. Considering the significant correlation (a correlation coefficient of 0.709) between subsidence and groundwater level decline, it can be concluded that one of the main causes of subsidence in Asadabad Plain is the depletion of groundwater resources. The assessment of land-use changes also reveals an increasing trend in agricultural land and human-built areas, corresponding to increased exploitation of groundwater resources and intensified land surface pressure, leading to exacerbated subsidence. Given the persistence of subsidence in this plain, remote sensing monitoring and the establishment of fixed GPS measurement stations facilitate monitoring the rate and extent of subsidence.