利用EOF分析濁水溪沖積扇地表變形

由於超抽地下水的原故，在濁水溪沖積扇區域有大範圍的地層下陷問題，特別是在雲林地區，這個問題又特別嚴重。水準測量、全球定位系統(GPS)，地層下陷監測井以及雷達干涉技術是地層下陷對於這個區域的監測方法。在我們的研究中，我們蒐集了此區域中27個GPS固定站資料，目的是為了要研究濁水溪沖積扇的地層下陷的變形情況，所選取的時間段中是從2010年到2015年。而在分析方法中則是選用了經驗正交函數這個時間序列分析法，希望可以得到由地層下陷造成的空間分佈以及測站中時間序列變化情況。對於我們的分析，我們設定了6種情況結合GPS的大地測量技術以及時間序列EOF分析法進行分析。成果顯示了此區域的變形情況及變形機制，最後我們藉由比對我們的結果與經濟部水利署(WRA)的地層下陷報告，成果相似的情況。所以本研究可以說明應用GPS結合EOF可以有效的監測濁水溪沖積扇(CRAF)的空間分佈以及時間序列特徵。

關鍵字

濁水溪沖積扇；地層下陷； GPS固定站；經驗正交函數(EOF)

並列摘要

Excessive pumping of groundwater has caused large-scale land subsidence in the Choshui River Alluvial Fan (CRAF), especially in the area of Yunlin country. Leveling, Global Positioning System (GPS), multi-level compaction monitoring well, and Interferometric Synthetic Aperture Radar(InSAR) are used to study the extent of subsidence in Yunlin and its mechanism. In this study, time series of elevation changes over 2010- 2015 derived from data at 27 Continuous GPS stations are used to examine the extent of subsidence in CRAF. An EOF analysis is used to identify the spatial pattern of subsidence and the time evolution of subsidence. We set 6 conditions to examine the GPS time series in the EOF analysis. The EOF result provides evidence linking the GPS-derived subsidence to its mechanism in CRAF. We compare our EOF results with those from Water Resources Agency (WRA) subsidence reports, and the two are consistent. Our study suggests that GPS can effectively monitor land subsidence and EOF can identify the spatial-temporal features of the subsidence in CRAF.

並列關鍵字

Choshui River Alluvial Fan(CRAF) ； Land Subsidence ； Continuous GPS ； Empirical Orthogonal Function (EOF)

參考文獻

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[3] E. T.Y. Chang, B. F. Chao, 2014. Analysis of coseismic deformation using EOF method on dense, continuous GPS data in Taiwan. Tectonophysics, 637 (2014) 106–115.

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國際替代計量

利用EOF分析濁水溪沖積扇地表變形

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