Study of surface deformation induced from fluctuation of roundwater in Taipei basin by PSInSAR
Date Issued
2015
Date
2015
Author(s)
Chang, Yan-Ru
Abstract
Taipei is the political and economic center in Taiwan. The active Shanchiao fault is located in the western margin of Taipei basin. Therefore, it is a crucial issue to better understand the assessment and mitigation of geological hazard in terms of monitoring of surface deformation in Taipei basin. Previous study suggested that three major factors influence the surface deformation in Taipei basin, such as soil compaction, groundwater fluctuation and tectonic movement. Consequently the assessment in activity of the Shanchiao fault, the deformation induced from fluctuation of the water table and soil compaction should be removed. Persistent Scatterers interferometric synthetic aperture radar (PSInSAR) technique is applied to calculate the surface deformation rate with the constraints of continuous GPS and precise leveling measurements. C-band ERS-1/2 (1996/1-1999/9), ENVISAT (2003/1-2008/3), L-band ALOS (2007/4-2011/6) and X-band COSMO-SkyMed (2011/5-2015/4) SAR images are used to characterize surface deformation in different periods. Based on the results of different periods of PSInSAR, the deformation rate along line of sight was variable via time which might be related to the deformation in different depth of loose deposits in Taipei basin. If the footwall of the Shanchiao fault is taken as a reference, the average LOS rate in the hanging wall of the Shanchiao fault is about 3 mm/yr in ERS-1/2 period, -1.8 mm/yr in ENVISAT period, 0.7 mm/yr in ALOS period and 1.6 mm/yr in COSMO-SkyMed period respectively. These results suggests that the slight uplift observed in the period of 2003/1-2008/3 and the slight subsidence occurred in the periods 1996/1-1999/9, 2007/4-2011/6 and 2011/5-2015/4. To characterize the relationship between surface deformation and groundwater table, cross-correlation and correlation coefficient were used to figure out the degree of time-delay in surface deformation following the fluctuation of groundwater table. Finally the storativity of Jingmei and Wuku formations are calculated. The results suggest that the surface deformation in Taipei area are mainly caused by consolidation of clay layers in Shongshan formation. The storativities of Jingmei and Wuku formations are between 0.7 × 10−3 and 2.0 × 10−3, respectively.
Subjects
PSInSAR
Surface deformation
water table
Taipei basin
Cross-correlation
Correlation coefficient
Storativity
Type
thesis
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