نوع مقاله : مقاله پژوهشی
نویسندگان
1 رئیس اداره ترازیابی دقیق و تداخل سنجی راداری، سازمان نقشه برداری کشور، تهران، ایران.
2 معاون اداره کل نقشه برداری زمینی، سازمان نقشه برداری کشور. تهران، ایران.
3 اداره کل نقشه برداری زمینی، سازمان نقشه برداری کشور. تهران، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Earth surface subsidence due to the over-extraction of underground water resources is considered a global crisis, which causes serious economic damage and threatens the safety of the residents of these areas. One of the most important subsidence risks is the formation and development of ground fissures. Identifying areas with surface ruptures can play a significant role in risk management and assessing, strengthening, and improving the structures located in these areas. The ground ruptures in the Kashan Plain are a clear example of surface ruptures caused by excessive extraction of underground water resources and land subsidence. Since horizontal displacements have also occurred in ruptures caused by land subsidence, estimating the horizontal component of subsidence can help locate the places where ruptures are formed. On the other hand, fissures occur in areas with asymmetric subsidence due to the change in the slope of the bedrock. Therefore, determination of the vertical displacement gradient can lead to the identification of places with high changes in the displacement rate and, as a result, the places where cracks are created. In this research, for the first time, the horizontal displacement component and the subsidence gradient map for Kashan Plain, obtained from the radar interferometry measurements. These maps are applied to identify the probable places of ruptures. Field visits have shown that the location of the ruptures is consistent with places with horizontal displacement and high subsidence gradients.
کلیدواژه‌ها [English]
Earth surface subsidence is a gradual decrease in the height of the earth's surface due to human intervention, such as over-extraction of underground water, oil and gas extraction, mining activities, or as a result of tectonic phenomena, which can have a small horizontal displacement vector. Due to the lack of sustainable management of underground water resources, various regions in the world have faced widespread subsidence. One of the most important dangers of the subsidence phenomenon is the formation and development of ground fissures. Therefore, identifying the location of these fissures caused by subsidence is considered a key issue in urban management.
In Iran, the over-extraction of underground water resources and the global consequences of climate change have caused land subsidence in many areas of the country. As an example, Kashan Plain is a prominent example of subsidence areas with numerous cracks.
In this research, the displacement field obtained from the radar interferometric technique and its gradient are applied to predict ground fissures formed due to the subsidence of the Kashan Plain and to identify areas prone to creating future fissures. This analysis can be applied to identify and reduce damage to surface and subsurface structures in subsidence areas.
In this research, the ground surface displacement field in Kashan plain is determined by processing Sentinel-1 satellite radar images with GMTSAR software. Consequently, the area affected by the subsidence phenomenon in Kashan plain has been identified and evaluated. To estimate the horizontal and vertical components of the displacement caused by the subsidence in the Kashan plain, 30 Sentinel-1 radar images of the area from the ascending orbit and 30 radar images of the area from the descending orbit from December 2020 to December 2022 obtained from the European Space Center. These images are processed with GMTSAR software.
On the other hand, since the areas with asymmetric subsidence are more prone to form cracks and sinkholes and damage to the surface and subsurface structures, in order to prepare the subsidence risk map, the land subsidence gradient map in Kashan plain was calculated.
The results show the areas with maximum horizontal displacement and maximum vertical displacement gradient are matched. A field visit to the subsidence area showed the creation of wide interconnected cracks and sinkholes in the areas with maximum horizontal displacement and a displacement gradient of more than 10%.
Therefore, it can be concluded that the gradient of vertical displacement and horizontal displacement determination can provide us with a map of high-risk areas of subsidence in terms of forming cracks on the surface and structures. Therefore, it is suggested to calculate these hazard maps for all subsidence areas in order to speed up the process of reviewing and consolidating local facilities and structures.
All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.
Data available on request from the authors.
The authors would like to thank the reviewers and editor for their critical comments that helped to improve the paper. The authors gratefully acknowledge the support and facilities provided by the National cartographic center of Iran.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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