QE535 : Study of landsubsidence due to excessive groundwater extraction in Semnan plain, using Sentinel satellite data
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2023
Authors:
Leyla Helali [Author], Rahim Bagheri[Supervisor], [Advisor]
Abstarct: The increase in population and overexploitation of groundwater for agricultural and industrial purposes has reduced the groundwater table and is one of the main causes of land subsidence in this region. In this research, the areas with subsidence and its rate were evaluated with high accuracy using the radar interferometry technique (RIT). Sentinel-1 satellite images were obtained in 2014 and 2021, and SNAP software was used to process the images. According to the obtained results, the maximum subsidence rate during the studied period was obtained 6 cm for two zones including the central part of the plain and south-southeast of Semnan city and the second zone in the southwest of the plain and south of Sufi Abad village. In the next step, using the data collected from 23 piezometric wells of the plain, the map of iso-drawdown map and the unit hydrograph for the seven-year interval were drawn and analyzed. The minimum water level drop during the 7-years is 0.15 meters in the Jafarabad piezometer and the maximum is 8.4 meters in the Afaghane town piezometer. Also, to evaluate the accuracy of the subsidence map which was obtained from the radar interferometry method, a subsidence potential map was prepared using two weighted laxyers, including an iso-drawdown map and prone to subsidence laxyers map. Comparing these two subsidence maps shows that they have a fair convergence with each other. Also, morphological evidence such as the growth value of the piezometer’s casing were used to evaluate the occurred actual subsidence value. The comparison shows that the obtained rate by RIT is consistent with the observed subsidence values and therefore, it can be concluded that the radar interferometric method has an appropriate capability and accuracy to evaluate the subsidence of the plains.
Keywords:
#Keywords: Subsidence #SNAP #underground water #radar interferometry #Semnan Plain Keeping place: Central Library of Shahrood University
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