(1) In 2020, the maximum annual subsidence rate measured in Taipei area is 1.5 cm/year. It is located in Wugu District with a significant subsidence area of 0.0 square kilometers. The subsidence rate at most detection points is about ±1 cm/year, and there is no significant surface change. ; Leveling test results show that there has been no significant subsidence in the Taipei area for nearly 8 years.
(2) In 2020, the main sag detection points measured in the entire Taipei area are shown in Table 1; the average sag rate from 2018 to 2020 is shown in Figure 1.
(3) According to the results of the leveling survey in Taipei in 2020, a total of 12 pile points have a sinking rate greater than 1.0 cm/year, and the sinking rates of the remaining test points are all within 1.0 cm/year. Among them, the water conservancy inspection in Wugu District The 48-3 has the largest sinking rate, reaching 1.5 cm/year. For the inspection points near Taipei Main Station, except for the water conservancy inspection 151, which has a sinking rate of 1.2 cm/year, the sinking rates of all other inspection points are within 1.0 cm/year; for the inspection points near Taipei Cultural and Sports Park, the sinking rate is 1.0 cm/year. Within cm/year, it means that there is no significant change around the Taipei Cultural and Sports Park.
(4) This project uses Sentinel 1-A images and SBAS (Small BAseline Subset) methods for data calculation. The image calculation period of each region matches the leveling period of this year: The current Sentinel-1 results show, September 2019 From January to September 2020, there is no obvious subsidence area in the Taipei Basin, and the overall vertical change rate is about ±1.5 cm/year. (September 108-September 109)
((5) Conclusion: (a) The subsidence rate of the Taipei trunk line in 2020 and the detection points in Taipei area from 2018 to 2020 is mostly about 1 cm, the maximum subsidence rate is 1.5 cm/year, and the significant subsidence area is 0.0 square kilometers. Taipei The area currently has no significant subsidence area. Analysis of water level data shows that the groundwater level in most areas of Taipei has dropped significantly after 2019. This phenomenon may be the reason for the increase in subsidence in Taipei this year compared to last year.
(b) At the inspection point near Taipei Main Station, the monitoring results showed no significant subsidence. However, the sinking rate of the 151 piles at the east side of the Taipei Main Station is 1.2 cm/year, a slight increase from 2019. This area needs continuous attention.
(c) The monitoring results of the inspection points of Taipei Big Arena show that the annual distribution of the heights of the inspection points is within plus or minus 1 cm, and there is no significant subsidence. Since the Big Arena has resumed construction, special attention should be paid to the subsidence of the area in the future.