Geomorphology
Masoumeh Rajabi; Shahram Roustaie; Seyed Mohammad Reza Javadi
Abstract
IntroductionLand subsidence is commonly referred to as vertical downward movements of the earth's surface that can be accompanied by a slight horizontal vector. Land subsidence is a global problem and a morphological phenomenon. This phenomenon is affected by human activities and natural factors that ...
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IntroductionLand subsidence is commonly referred to as vertical downward movements of the earth's surface that can be accompanied by a slight horizontal vector. Land subsidence is a global problem and a morphological phenomenon. This phenomenon is affected by human activities and natural factors that may become a threat to humans and human achievements. The phenomenon of subsidence, although imperceptible and gradual, but is associated with many risks, including the creation of potholes, failure and cracking of buildings, skewing of high facilities, damage to agricultural facilities, breakage and destruction of stairs Roads and network of urban thoroughfares. Therefore, this issue affects the urban areas more, which if not addressed can lead to many human and financial losses. Accordingly, monitoring the rate of land subsidence in order to reduce the negative effects as well as controlling its development process, will be very important and it is necessary to regularly estimate the area subsidence trend. Due to the importance of the issue, in recent years, various studies have been conducted in the field of subsidence and advances in the field of remote sensing have led to monitoring the phenomenon of subsidence, unlike in the past, with greater accuracy and speed. One of the methods that has received a lot of attention in recent years is the radar interference method, which has high accuracy and speed in processing information and monitoring land surface changes, so in this study, this method is used to monitor the situation. Subsidence of cities located in Hamedan-Bahar plain has been used.Materials and methodsIn this study, in accordance with the intended objectives of Sentinel 1 radar images (73 radar images during the period 16/01/2015 to 14/01/20120), the information of piezometric wells in the region (related to the Water and Regional Organization of Hamadan Province ) And the 30 m SRTM digital elevation model have been used as research data. Important research tools also include GMT (for radar interference measurement and SBAS time series) and ARCGIS (for mapping). This research has been done in 2 general stages. In the first stage, the amount of subsidence in the area is assessed using radar images. In order to perform this step, radar interferometry and SBAS time series method have been used. In the second stage, the annual drop in groundwater in the region is evaluated. At this stage, in order to assess the annual drop in groundwater in the region, information about 25 piezometric wells located in the study area in the period of 1375 to 1395 has been used.Discussion and resultsThe study of subsidence results in the study cities indicates that the average annual subsidence in the urban area of Hamedan was about 23 mm, the highest amount of which was related to the western regions of the city. The average annual subsidence in the urban area of Bahar was about 9 mm, the highest rate of subsidence was in the southern areas of the urban area. The average annual subsidence in the urban area of Salehabad with 6 mm was lower than other cities, but the average annual subsidence of Lalejin with 47 mm was the highest among cities. Also, in this research, information related to 25 piezometric wells (statistical periods of wells related to the years 1375 to 1695) located in the study area has been used. Examination of the level of water level drop in the studied wells indicates that these wells have faced a lot of water level drop, so the average annual drop of wells is calculated between 100 to 2070 mm. The study of the spatial status of groundwater depletion indicates that the middle areas of the study area have the highest average annual groundwater level depletion.ConclusionThe results obtained from the assessment of subsidence in the studied urban areas indicate that the highest amount of subsidence occurred in the urban area of Lalejin, so that this area during a period of 5 years (01/16/2015 to 01/14 /2020) had a subsidence between 26 and 234 mm (average annual 47 mm). In this study, the situation of groundwater resources decline has also been evaluated. The results show that the average annual drop of wells in the region is between 100 to 2070 mm, which is the highest rate of decline in the middle areas of the study area, and given that in this region, the highest rate of subsidence also occurred. Given that there is a significant relationship between land subsidence and groundwater level decline (correlation 0.7). In fact, a study of the subsidence of cities in relation to the decline of groundwater resources indicates that the city of Lalejin, due to its location in the middle of the area and the high annual rate of groundwater decline, had the highest rate of subsidence. Also, the results of evaluations have shown that in addition to the decrease of groundwater resources, constructions have also played a role in increasing the rate of subsidence, so that the city of Hamedan has faced less groundwater loss than the city of Bahar, but it had more subsidence. Considering that the highest rate of subsidence occurred in the western, southern and eastern regions of Hamedan urban area and these areas have faced a lot of physical development in recent years, so it can be said that in addition to water loss Underground, the development of construction has also played an important role in the rate of subsidence in this city.
Geomorphology
Mousa Abedini; Elhameh Ebady; Ehsan Ghale
Abstract
Introduction Landslides are one of the major geological problems around the world that cause compaction of subsurface layers. The cause of this phenomenon can be attributed to human activities such as uncontrolled abstraction of groundwater and natural activities such as earthquakes. Landslides ...
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Introduction Landslides are one of the major geological problems around the world that cause compaction of subsurface layers. The cause of this phenomenon can be attributed to human activities such as uncontrolled abstraction of groundwater and natural activities such as earthquakes. Landslides are also one of the main geological hazards in the region, causing serious damage to buildings, roads, infrastructure and bridges. According to the US Geological Survey, subsidence involves the collapse or subsidence of the earth's surface, which can have a small displacement vector. Therefore, identifying and monitoring the subsidence phenomenon is one of the most important and vital issues to maintain stability in the regions. For this purpose, researchers use various methods to study and observe this phenomenon, which are divided into three categories based on the position of the tools used: Subsurface methods, Ground Based methods and Remote Sensing methods. One of the most important of these methods is remote sensing, which collects data from the air or space using satellites, airplanes, or unmanned vehicles and balloons. Radar interference or InSAR, as one of the methods of processing radar images in active remote sensing, is one of the most accurate and economical methods that allows the detection and detection of differences in altitudes created in the shortest time and for large areas. Data and Method The study area is located in western Iran and one of the parts of Kermanshah city located in Kermanshah province is located in the area between latitudes 42 degrees and 9 minutes north and longitude 36 degrees and 2 minutes east. Radar interferometry studies in this study were taken by sentinel 1 satellite imagery of the C band. In this study, data from Sentinel 1 satellite in C-band were used. Using image processing with SARSCAPE 5.2 plugin in ENVI 5.3 software platform and using interferometry method, areas exposed to subsidence and the amount of subsidence in each area were determined. In the present study, the relationship between groundwater level drop and subsidence of Mahidasht plain has been investigated. For this purpose, groundwater depth data of 31 piezometer wells in Mahidasht plain were used. In terms of time, considering the accurate and available statistics, the statistics of 1394 and 1398 were cited. The steps of the research were as follows: after preparing the statistics of piezometric wells, the data reconstruction method was used to eliminate the deficiencies in the study data. The reconstruction method used, which was used only to correct the defects in the data, is the interpolation method, which was performed by Neural Power software (based on artificial neural network). To normalize the data, logarithmic transformations were used in SPSS 16 software and GS+ software was used for geostatistical analysis. Results and Discussion Examination of subsidence status during the study years shows that from 2015 to 2020, the rate of subsidence has increased. In Figure 1, the areas marked in red have the highest subsidence, the areas marked in green and yellow have the least subsidence, and the areas marked in black have no subsidence. According to the subsidence map of the region, the maximum average subsidence rate in the study area reaches 16 cm. According to the extracted subsidence map of the study area, it is observed that the highest amount of subsidence occurred in the eastern part of Mahidasht plain, which decreased to the west of the plain, so that in the western and south western part of the plain, the lowest Subsidence is observed. Relationship between groundwater extraction and land subsidence phenomenon Considering that groundwater abstraction is one of the important causes of subsidence in Mahidasht plain, in order to explain the trend of groundwater level changes, the general trend of annual water level of all wells were examined. According to the groundwater level interpolation map, the groundwater depth in Mahidasht plain varies from a maximum of 21.62 meters in 1994 to a maximum of 24.71 meters in 1998. ConclusionLand subsidence is a pervasive phenomenon in the world, which has had a significant quantitative and qualitative manifestation in recent decades, mainly due to the improper exploitation of groundwater resources and the intensification of its decline. In the present study, the relationship between groundwater level drop and subsidence of Mahidasht plain has been investigated. Examination of statistics related to the depth of study wells as well as groundwater level zoning maps confirm the decrease of groundwater level. In fact, over-harvesting and lack of balance between feeding the aquifers and draining them has caused the water table in the region to follow a continuous downward trend, with the emptying of water in the cavities of the aquifer and the displacement of water in these cavities with Air reduces the equilibrium pressure between the layers. Due to the disturbance of the balance between the pressure and the weight of the upper layers, due to the force of the weight of the upper layers, the aqueous layers are compressed and the water table decreases and because this decrease has a direct relationship with subsidence. Therefore, in order to deal with this environmental problem, it is recommended to prevent the development of subsidence in the region or to minimize the occurrence of this phenomenon as much as possible by managing land use in the area of subsidence and also adequate supervision over the extraction of underground resources.
Abolghasem Amirahmadi; Nasim Maali Ahari; Tayebeh Ahmadi
Volume 17, Issue 46 , February 2014, , Pages 1-23
Abstract
Ardebil plain, an area of approximately 1097.23 km2 in geographic coordinates of 38˚ 5¢ to 38˚ 27¢ north latitude and 48˚ 9¢ to 48˚ 37¢ eastern longitude, is a valley plain. During recent years, groundwater has been stuck with eye drops. This article reviews the changes occurred ...
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Ardebil plain, an area of approximately 1097.23 km2 in geographic coordinates of 38˚ 5¢ to 38˚ 27¢ north latitude and 48˚ 9¢ to 48˚ 37¢ eastern longitude, is a valley plain. During recent years, groundwater has been stuck with eye drops. This article reviews the changes occurred in the volume of water aquifer and the rate of decline in groundwater in the plain out of the data from wells by using the software ArcGIS, piezometers maps and drop zone in the area under study. Graphical maps showed that the highest rate of water loss has occurred in the southeastern region. The zoning plan was provided, and it showed that 14% of the drop zone area was in the high plains, 29.73% in the high zone, and 26.6% in the intermediate zone, 17.38% in the low zone and 12/29% of the drop zone are low. The results indicate that the aquifer is in a critical condition in Ardebil. To explore the possible future subsidence, affecting layers included: precipitation, slope, hydrology, lithology, geomorphology, soil, vegetation and human factors extracted from maps and combining layers in GIS. map projections drop of water method were developed in the future using underground Co-Kriging point. The results showed that it is most likely that in the future Ardebil method subsidence would occur due to excessive removal of groundwater resources in the south east will and human activity in the west plains subsidence are the second risky factor.
