運用GPS衛星定位監測彰化沿海地區地層下陷之研究

The Study of Using GPS Measuring Height to Survey Subsidence in Changhua Area

彰化沿海地區位於濁水溪沖積扇平原之北部，依據經濟部近年地層下陷監測井及地表水準點研究結果顯示2001、2002、2003年間，最大年下陷速度分別為17.6cm/yr、11.7cm/yr及10.4cm/yr，顯示地層下陷問題嚴重，政府部門需再投入研究，避免各項民生及重大工程（如高速鐵路、濱海工業區及東西向快速道路）遭受衝擊，並及早提出因應之道。本次研究主要目的為對於地層嚴重下陷地區，使用長期觀測監測方式配合數學線性迴歸原理，希望能夠得到與連續站方式類似成果及趨勢，但所需經費較為節省且作業更為便利。由監測成果分析，彰化沿海地區屬嚴重地層下陷地區，除VR02每年下陷約80mm最為嚴重外，本次監測其餘一等水準點每年下陷也約在17-56mm間。另研究成果顯示，採GPS監測與一等水準檢測方法，所分析點位下陷速度趨勢一致。 The Changhua coastal area is located on the north Jhuoshuei River alluvial plain. The velocitiesof land subsidence during 2001, 2002, 2003 respectively were 17.6 cm/yr, 11.7 cm/yr and 10.4 cm/yr, based on the studies of the Ministry of Economic Affairs. Realizing this dire problem, we need tostudy the land subsidence in this area in order to prevent or mitigate the possible impact on localinfrastructure.The goal of this research is to obtain the similar achievement and the tendency comparing withthe results of the permanent sites, using long-term monitoring observations and linear regression method. And the method proposed in this study is more cost-effective. The achievementdemonstrated that the Changhua coastal area has been still the serious land subsidence area. VR02 isthe most serious land subsidence point which the displacement is nearly 80mm per year. Thedisplacement of 1st order benchmarks were nearly 17~56mm per year during the monitoring period.The velocities of land subsidence of all most points were the same between Global PositioningSystem (GPS) and leveling survey results.

The Changhua coastal area is located on the north Jhuoshuei River alluvial plain. The velocitiesof land subsidence during 2001, 2002, 2003 respectively were 17.6 cm/yr, 11.7 cm/yr and 10.4 cm/yr,based on the studies of the Ministry of Economic Affairs. Realizing this dire problem, we need tostudy the land subsidence in this area in order to prevent or mitigate the possible impact on localinfrastructure.The goal of this research is to obtain the similar achievement and the tendency comparing withthe results of the permanent sites, using long-term monitoring observations and linear regression method. And the method proposed in this study is more cost-effective. The achievementdemonstrated that the Changhua coastal area has been still the serious land subsidence area. VR02 isthe most serious land subsidence point which the displacement is nearly 80mm per year. Thedisplacement of 1st order benchmarks were nearly 17~56mm per year during the monitoring period.The velocities of land subsidence of all most points were the same between Global PositioningSystem (GPS) and leveling survey results.