Faculty of Geography, University of Tehran, Tehran, Iran. , h.ganjaeian@ut.ac.ir
Abstract: (208 Views)
1-Introduction
Subsidence is the collapse or subsidence of the earth's surface, which occurs for different reasons on a large scale. Usually, this term refers to the downward vertical movement of the earth's surface, which can be accompanied by a small horizontal vector. In many cases, subsidence takes place imperceptibly and gradually, and it is one of the risks whose effects are visible in the long term. One of the most important effects of subsidence is a sinkhole, which can cause many human and financial losses. Usually, areas that face the risk of subsidence will also face the risk of sinkholes in the long term, so it is necessary to control the increasing process of subsidence. The geographical location of Iran has caused many parts of it to be at risk of subsidence. The Qorveh plain in the east of Kurdistan province is one of the plains that has faced the crisis of subsidence due to its hydroclimatic and geomorphological conditions. In terms of geomorphology, Qorveh plain has few limiting obstacles and this problem has provided the basis for the development of human activities including agricultural activities in this plain. Due to the fact that the average rainfall of Qorve plain is about 300 mm and this plain is facing a shortage of surface water resources, therefore a large part of the water resources needed by the agricultural lands of this plain is supplied through underground water sources and this problem causes There has been a sharp drop in the underground water resources of this plain in recent years. Due to the sharp drop in underground water resources and the risk of subsidence, it can be expected that if the current trend continues, the Qorve plain will also face the crisis of sinkholes. Due to the importance of the issue, in this research, using radar images, areas prone to sinkholes have been identified in this plain.
2- Methodology
In this research, Sentinel 1 radar images, Landsat 8 satellite image, information related to piezometric wells in the area and SRTM 30 meters high digital model have been used as the most important research data. The most important tools used in the research are ArcGIS (in order to prepare the desired maps and final outputs), GMT (in order to implement the radar interferometry process), and ENVI (in order to prepare the land use map of the region). And Expert Choice (in order to give weight to the presented solutions). Also, in this research, SBAS time series models (to prepare the final subsidence map of the region), maximum likelihood (to prepare the land use map of the region) and AHP (to weight the proposed solutions) have been used. According to the objectives, this research has been done in 3 stages. In the first step, using Sentinel 1 radar images and the radar interferometry method and SBAS time series, the amount of vertical displacement in the study area has been evaluated. In the second stage, on the basis of the prepared map, library studies, as well as experts' opinions, the areas prone to sinkholes have been identified in Qorve Plain. After identifying the areas prone to sinkholes, the distribution of population points exposed to them has been evaluated. In the third stage, the effective factors in the subsidence of the region have been analyzed and effective solutions have been provided to control it.
3- Results
Examining the state of subsidence occurred in the Qorve plain has shown that this plain has subsided a maximum of 379 mm during a period of 4 years. Therefore, it can be said that the Qorve plain has faced the maximum annual subsidence of about 10 cm. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this hazard have been identified. In order to identify areas prone to sinkholes, areas that have subsidence of more than 200 mm during a period of 4 years (areas that have subsidence of more than 5 cm per year) as areas in They have been identified as prone to sinkholes. It should be noted that the selection of 200 mm was based on the subsidence of the region, the topography of the region, and library studies. According to the results, the areas adjacent to Dezaj city and the areas adjacent to Vinsar, Shekohabad and Ganji villages have a high potential in terms of sinkhole occurrence.
4-Conclusion
The location of Qorve plain has made this plain one of the critical plains in the west of the country. Due to its hydroclimatic situation, Qorveh plain is facing a shortage of surface water resources, and this problem has caused excessive use of underground water resources in this plain. Excessive use of underground water resources in the Qorve plain has caused this plain to face a severe drop in underground water resources, so that the annual average drop of underground water in many parts of this plain has been more than 1 meter. The severe drop in underground water resources has caused the Qorve Plain to face 379 mm of subsidence during the years 2018 to 2022, so the Qorve Plain is facing a subsidence crisis. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this risk (areas with subsidence of more than 5 cm per year) have been identified. Based on the results, the areas adjacent to Dezaj city, the areas adjacent to Vinsar village, the areas adjacent to Shekohabad village and also the areas adjacent to Ganji village have a high potential in terms of sinkhole occurrence. Considering that sinkholes are associated with many human and financial losses, in this research, in order to control the subsidence and prevent the occurrence of sinkholes in Qorve plain, various solutions have been presented, and then, using the AHP model, the most important solutions have been selected. Is. Based on the results, planning based on the environmental capabilities of the Qorve plain with a weight of 0.288 has been selected as the most important solution, followed by the solutions of improving irrigation methods and preventing the cultivation of short-term crops, respectively, with a weight of 0.217 And 0.172 have been selected as the most important solutions.
Subsidence is the collapse or subsidence of the earth's surface, which occurs for different reasons on a large scale. Usually, this term refers to the downward vertical movement of the earth's surface, which can be accompanied by a small horizontal vector. In many cases, subsidence takes place imperceptibly and gradually, and it is one of the risks whose effects are visible in the long term. One of the most important effects of subsidence is a sinkhole, which can cause many human and financial losses. Usually, areas that face the risk of subsidence will also face the risk of sinkholes in the long term, so it is necessary to control the increasing process of subsidence. The geographical location of Iran has caused many parts of it to be at risk of subsidence. The Qorveh plain in the east of Kurdistan province is one of the plains that has faced the crisis of subsidence due to its hydroclimatic and geomorphological conditions. In terms of geomorphology, Qorveh plain has few limiting obstacles and this problem has provided the basis for the development of human activities including agricultural activities in this plain. Due to the fact that the average rainfall of Qorve plain is about 300 mm and this plain is facing a shortage of surface water resources, therefore a large part of the water resources needed by the agricultural lands of this plain is supplied through underground water sources and this problem causes There has been a sharp drop in the underground water resources of this plain in recent years. Due to the sharp drop in underground water resources and the risk of subsidence, it can be expected that if the current trend continues, the Qorve plain will also face the crisis of sinkholes. Due to the importance of the issue, in this research, using radar images, areas prone to sinkholes have been identified in this plain.
2- Methodology
In this research, Sentinel 1 radar images, Landsat 8 satellite image, information related to piezometric wells in the area and SRTM 30 meters high digital model have been used as the most important research data. The most important tools used in the research are ArcGIS (in order to prepare the desired maps and final outputs), GMT (in order to implement the radar interferometry process), and ENVI (in order to prepare the land use map of the region). And Expert Choice (in order to give weight to the presented solutions). Also, in this research, SBAS time series models (to prepare the final subsidence map of the region), maximum likelihood (to prepare the land use map of the region) and AHP (to weight the proposed solutions) have been used. According to the objectives, this research has been done in 3 stages. In the first step, using Sentinel 1 radar images and the radar interferometry method and SBAS time series, the amount of vertical displacement in the study area has been evaluated. In the second stage, on the basis of the prepared map, library studies, as well as experts' opinions, the areas prone to sinkholes have been identified in Qorve Plain. After identifying the areas prone to sinkholes, the distribution of population points exposed to them has been evaluated. In the third stage, the effective factors in the subsidence of the region have been analyzed and effective solutions have been provided to control it.
3- Results
Examining the state of subsidence occurred in the Qorve plain has shown that this plain has subsided a maximum of 379 mm during a period of 4 years. Therefore, it can be said that the Qorve plain has faced the maximum annual subsidence of about 10 cm. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this hazard have been identified. In order to identify areas prone to sinkholes, areas that have subsidence of more than 200 mm during a period of 4 years (areas that have subsidence of more than 5 cm per year) as areas in They have been identified as prone to sinkholes. It should be noted that the selection of 200 mm was based on the subsidence of the region, the topography of the region, and library studies. According to the results, the areas adjacent to Dezaj city and the areas adjacent to Vinsar, Shekohabad and Ganji villages have a high potential in terms of sinkhole occurrence.
4-Conclusion
The location of Qorve plain has made this plain one of the critical plains in the west of the country. Due to its hydroclimatic situation, Qorveh plain is facing a shortage of surface water resources, and this problem has caused excessive use of underground water resources in this plain. Excessive use of underground water resources in the Qorve plain has caused this plain to face a severe drop in underground water resources, so that the annual average drop of underground water in many parts of this plain has been more than 1 meter. The severe drop in underground water resources has caused the Qorve Plain to face 379 mm of subsidence during the years 2018 to 2022, so the Qorve Plain is facing a subsidence crisis. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this risk (areas with subsidence of more than 5 cm per year) have been identified. Based on the results, the areas adjacent to Dezaj city, the areas adjacent to Vinsar village, the areas adjacent to Shekohabad village and also the areas adjacent to Ganji village have a high potential in terms of sinkhole occurrence. Considering that sinkholes are associated with many human and financial losses, in this research, in order to control the subsidence and prevent the occurrence of sinkholes in Qorve plain, various solutions have been presented, and then, using the AHP model, the most important solutions have been selected. Is. Based on the results, planning based on the environmental capabilities of the Qorve plain with a weight of 0.288 has been selected as the most important solution, followed by the solutions of improving irrigation methods and preventing the cultivation of short-term crops, respectively, with a weight of 0.217 And 0.172 have been selected as the most important solutions.
Type of Study: Research |
Received: 2023/10/3
Received: 2023/10/3
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