Geomorphology
sayyad Asghari Saraskanroud; Fariba Esfandyari; Mehdi Faal Naziri; Batool Zeinali
Abstract
Land subsidence refers to the gradual or sudden lowering of the earth's surface as a result of various factors such as tectonic activities, mining, oil and gas fields, and illegal extraction of underground water. In Alborz province, the growing trend of population and migration in recent years has ...
Read More
Land subsidence refers to the gradual or sudden lowering of the earth's surface as a result of various factors such as tectonic activities, mining, oil and gas fields, and illegal extraction of underground water. In Alborz province, the growing trend of population and migration in recent years has added to the increase in demand and the amount of water withdrawal from the underground water table, so it is subject to subsidence due to the sharp drop in the level of underground water. In this research, subsidence assessment was done using radar interferometric technique, and then, prone areas were zoned with multi-criteria algorithm in the time frame of 2016 and 2023. The results of information extraction with interferometric technique showed that the average amount of subsidence in the urban boundaries of Saujblag, Karaj, Nazarabad, Chaharbagh and Fardis is between 15 and 320 mm. According to observations, the highest amount of subsidence is in the eastern part and then in the southern and southwestern parts. According to the estimated results of subsidence risk zoning; The parameters of water level drop, land use, slope and geology, respectively, with weight coefficients of 0.16127, 0.141875, 0.130145 and 0.128474, are the most important factors in creating the risk of subsidence in the study area, which are 31 and 23%, respectively. From the range, it has a very high and high probability of danger.
Groundwater
Mohammad Hossain Motedayen; Mehrdad Esfandiari; Abolfazl Moeini; Ali Mohammadi Torkashvand
Abstract
In recent years, the irreversible phenomenon of land subsidence has led to environmental hazards in various plains of Iran including Gorgan. In general, the most important activities causing this phenomenon are inappropriate groundwater withdrawal and geological factors. The research method consists ...
Read More
In recent years, the irreversible phenomenon of land subsidence has led to environmental hazards in various plains of Iran including Gorgan. In general, the most important activities causing this phenomenon are inappropriate groundwater withdrawal and geological factors. The research method consists of two sections: identifying subsidence areas and examining the effective factors and parameters and evaluating the impact of each. In identification section, radar interferometry technique was used to compare the phase taken from two radar sets from the same region at two different times and measurement of land surface changes over time can be achieved through interferogram, and in the effective factors analyzing section, the determination and analysis of effective parameters such as water level drop, texture and thickness of soil layers, especially fine-grained layers were investigated. The results of the satellite data analysis indicate that the region is steadily subsiding. The mean velocity map along the satellite line of sight obtained from time series analysis showed a subsidence rate of 14 mm / month (169 mm / year). The identified subsidence range is approximately eastern-western which is consistent with trends in structures such as the Caspian. Figures of water level and precipitation in this area during 2007 to 2009 show a decreasing trend despite of seasonal fluctuations, and analysis of effective parameters shows that the subsidence is due to the same drop in water level or the difference of same thickness of the fine-grained layer at different depths
