以Sentinel-1A SAR及SBAS方法監測雲林地層下陷

雲林為地處濁水溪沖積平原之沿海地區，由於長期受到地層下陷影響，已對台灣高鐵的營運構成安全性威脅。因此，如何有效率地監測雲林地層下陷成為安全性評估之重要議題。在臺灣，合成孔徑雷達干涉技術（Interferometric Synthetic Aperture Radar，InSAR）已被廣泛使用於地層下陷監測中，然而，由於InSAR 技術受軌道誤差影響而在成果中有一線性梯度變化量，此研究藉由比較InSAR 技術取得之成果與GPS 取得之成果，以估算軌道誤差造成的影響量。本研究中利用2016 年4 月至2017 年4 月共35 幅Sentinel-1A 衛星影像（22 幅升軌影像及13 幅降軌影像），搭配短基線子集差分干涉法（Small Baseline subset，SBAS），並考慮軌道誤差造成的影響，以提升取得地層下陷監測成果之品質。由成果可見，Sentinel-1A 搭配SBAS 方法的成果與GPS 成果比較之均方根差，在升軌與降軌成果中分別為7.6 mm/yr 及33.6 mm/yr。在考慮軌道誤差後，均方根差異降低至6.2 mm/yr 及8.0 mm/yr，Sentinel-1A 搭配SBAS 方法的整體成果品質有大幅度地改善。後續將考慮軌道誤差之改正成果轉至垂直方向與水準測量成果進行比較，本研究為雲林地層下陷監測提供了大範圍與高精度之成果。

關鍵字

地層下陷； Sentinel-1A ；短基線子集差分干涉法；軌道誤差

並列摘要

Yunlin County, a coastal county in the Chuoshui River Alluvial Fan (CRAF), has long suffered from severe land subsidence, which poses a threat to the operation of the Taiwan High Speed Railway (THSR). Effective monitoring of Yunlin land subsidence is an important issue of hazard prevention. Interferometric Synthetic Aperture Radar (InSAR) has been widely used for monitoring land subsidence in Taiwan because of its high spatial resolution and wide swath. The orbital errors in InSAR technique cause systematic errors in results, this study estimates the orbital errors by comparing the differences between the InSAR-derived results and the GPSderived results. In this study, we used 35 Sentinel-1A images (22 images along the ascending track and 13 images along the descending track) from April 2016 to April 2017 to determine land subsidence by the method of Small BAseline Subset (SBAS). The orbital errors are then estimated to improve the overall quality of the Sentinel-1A-derived SBAS results. The Root Mean Square (RMS) differences between the Sentinel-1A results and GPS results in the one-year case are 7.6 mm/yr and 33.6 mm/yr using data from the ascending and descending tracks, respectively. And the RMS differences decrease to 6.2 mm/yr and 8.0 mm/yr after moving the effect of the orbital errors. The adjusted Sentinel-1A-derived results are converted to the rates along the vertical direction and compared with the leveling-derived results. This study provides wide-range and high-precision land subsidence rates compatible with those from GPS and leveling (within one mm/yr) in Yunlin.

並列關鍵字

land subsidence ； Sentinel-1A ； SBAS method ； orbital error

參考文獻

[1] C. Hwang, W.-C. Hung, and C.-H. Liu, “Results of geodetic and geotechnical monitoring of subsidence for Taiwan High Speed Rail operation,” Natural Hazards, vol. 47, no. 1, pp. 1–16, Oct 2008. [Online]. Available: https://doi.org/10.1007/s11069-007-9211-5

[4] C.-S. Hsieh, T.-Y. Shih, J.-C. Hu, H. Tung, M.-H. Huang, and J. Angelier, “Using differential SAR interferometry to map land subsidence: a case study in the Pingtung Plain of SW Taiwan,” Natural Hazards, vol. 58, no. 3, pp. 1311–1332, Sep 2011. [Online]. Available: https://doi.org/10.1007/s11069-011-9734-7

[18] C.-H. Liu, Y.-W. Pan, J.-J. Liao, C.-T. Huang, and S. Ouyang, “Characterization of land subsidence in the Choshui River alluvial fan, Taiwan,” Environmental Geology, vol. 45, no. 8, pp. 1154–1166, Jun 2004. [Online]. Available: https://doi.org/10.1007/s00254-004-0983-6

[26] A. Kohlhase, K. Feigl, and D. Massonnet, “Applying differential InSAR to orbital dynamics: a new approach for estimating ERS trajectories,” Journal of Geodesy, vol. 77, no. 9, pp. 493–502, Dec 2003. [Online]. Available: https://doi.org/10.1007/s00190-003-0336-3

[27] H. Bähr, Orbital Effects in Spaceborne Synthetic Aperture Radar Interferometry. KIT Scientific Publishing, Karlsruhe, 2013. [Online]. Available: http://dx.doi.org/10.5445/KSP/1000037166

國際替代計量

以Sentinel-1A SAR及SBAS方法監測雲林地層下陷

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