land subsidence

 Land subsidence is the gradual or sudden downward movement of the earth's surface, often resulting from the extraction of groundwater, minerals, or hydrocarbons. This phenomenon, which can cause significant structural damage and environmental degradation, is increasingly prevalent in regions with excessive groundwater abstraction. The primary objective of this study was to assess subsidence in Shiraz Plain, using radar interferometry to analyze ground deformation due to groundwater depletion and other environmental factors, such as droughts and historical lake bed conditions.

  This study employed ENVISAT ASAR C-band radar images from 2007-2009 to investigate subsidence patterns in the Shiraz Plain. The images were processed using ENVI5.3.1 software with the SARscape plugin, including interferometry, ADAPT filters, and Goldstein filtering to mitigate errors and improve image quality. The final phase-to-displacement conversion and geocoding steps resulted in subsidence maps, which were used to analyze displacement across different regions. The data were validated by comparing the generated subsidence maps with field observations.

 The analysis revealed subsidence rates ranging from -14 cm to +5 cm, with the most significant displacements observed in the southeast of Shiraz and parts of Beiza. Ground displacement in urban and agricultural areas was also notable, with an average subsidence rate of -3.5 cm. The primary causes of subsidence in these regions were identified as excessive groundwater extraction, historical lake bed conditions, and geological factors such as fault zones.

The study highlights the importance of sustainable groundwater management to mitigate subsidence risks, and recommends continued monitoring and implementation of water conservation strategies to prevent further ground displacement in the region.

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

The role of humans in anthropogenic erosion and geomorphological changes of its natural environment is very important. Its most important role in recent decades is the use of surface and groundwater resources, which has been clearly shown as the destructive effects of excessive use of groundwater. Therefore, the need for water resources has caused the withdrawal of these very valuable resources from the underground aquifers of the country, whether allowed or not, and is facing the risk of land subsidence. The construction of the dam was another destructive effect that played an important role in blocking the aquifer nutrition. Normanshir-Fahraj plain is one of the plains in the country which has been directly affected by dam construction and uncontrolled abstraction of groundwater. After the dewatering of Nesa Dam, we were witnessed many environmental and water crises downstream of the alluvial fans of Fahraj and Normanshir. The need for drinking water, irrigation of date orchards and other uses has led to high groundwater abstraction. Also, the subsidence is calculated using radar data Sentinel 1 satellite for 6 months about 10 cm, which is high. Therefore, it is necessary to pay attention to landslide risk management as well as to avoid secondary hazards such as the destruction of walls and buildings, road lines and the transfer of energy and infrastructure by the relevant governorate.

Land subsidence phenomenon due to human activities and natural factors has been observed in the plains of Fars province which impose heavy damage to agricultural lands, rural buildings and historical monuments. In this paper, after identifying and determining rate of damage in Fars province, Marvdasht plain and its damaged villages have been chosen as the case study. The land subsidence map of Marvdasht and villages were presented by the data obtained from state of ground water, soil and soil parameters. Also, the effect of faults, tectonic situation, dried qanat, occurred earthquakes in this area and the observed fissured are taken into account. Generally, uncontrolled withdrawals from deep drilling wells caused subsidence and extended damage in other areas. Earthquakes intensified the damage to rural buildings and contributed to opening gaps. The altered subsidence achieved in different parts of Marvdasht plain and the damage in rural areas along with the predictions made could represent the progressive damage of this phenomenon in the future. Finally, with respect to the climate, geology, land status, characteristic of soil layers and regional potential, appropriate solutions for the land subsidence prevention and consequently reduction of the related damages were presented.