圖書典藏及影音數位平台

依據民國98年行政院核定之地下水保育管理計劃，今年度繼續在宜蘭、台北、桃園、高雄與屏東等地區以多重感應器監測技術(包含水準測量、GPS固定站、地陷監測井與地下水位井等)進行地層下陷之嚴密監測，並同時針對新興異常與嚴重沉陷區進行下陷機制之分析與探討，而上述相關監測數據、調查資料與分析成果，未來將作為政府水資源規劃與防範地層下陷之重要參考依據。

This project involves the stage Ⅱ plan for the mitigation of land subsidence. Its objectives are to monitor the land subsidence and to explore the subsidence mechanisms in Taiwan. Consequently, these results will provide precaution for the potential areas of land subsidence and to develop the conceptual strategy for the mitigation of serious land subsidence. This project contains five tasks including: (1) leveling survey in land-subsidence area and groundwater monitoring stations of Pingtung, (2) maintenance and measurement of the existed land- subsidence monitoring wells and, (3) establish new GPS compaign in the eased subsidence area, (4) the integrated analysis of monitored data obtained from the land subsidence area, (5). renewal and maintenance of land subsidence database as well as a Web site inquiring system. The main results are summarized as follows: (1) The results of leveling survey The areas of leveling survey include Yilan (160 km), Taipei (270 km), Taoyuan (250 km), Kaohsiung (160 km), and Pingtung (250 km) and. The total length of surveyed routes is about 1,090 km. The surveyed routes’ closed errors are all satisfied the standard requirement of 3mm√k (k means the length in kilometers). The results of the leveling survey are as follows: (a) In Yilan, the land subsidence is under control for the subsidence rate of all the other area is less than 3 cm/yr besides Su’ao town. The most significant subsidence rate of the benchmarks around the local Hotel in Su’ao reachs 4.6 cm/yr. (b) In Taipei, there is no significant subsidence from the benchmarks level examation. Poveide care for the benchmark NO18-2 near the construction site of MRT which sinks continuously in recent two years shows subsidence rate beyond 1 cm/yr. (c) In Taoyuan, the amout of subsidence less than 1 cm/yr in recent year hints there is almost no subsidence. The average subsidence rate is less than 3 cm/yr through 2007 to 2010. (d) In Kaohsiung, the leveling survey, toal length about 160 km, has finished and the results will be thought to be the initial value for the future analysis. (e) In Pingtung, only Linbian and Jiadong Township’s subsidence rate is over 3 cm/yr. The maximum subsidence rate is about 4.3 cm/yr (Linbian Township) and the continuously subsiding area is 47.5 km2. (2) The results of data analyzed in land subsidence monitoring wells According to the measurements of all the 7 land-subsidence compaction monitoring wells including four in Pingtung and the others in Yilan, Taoyuan, and Kaohsiung respectively, only two wells in Fangliao and Jiadong both in Pintung show respectively the 1.8 and 1.6 cm/yr in compaction rate of entire measured depth and the others are less than 1 cm/yr. There is the only advanced compaction in Fanliau this year. (3) Establishment of new GPS compaigns in the eased subsidence area There are 14 GPS campaigns established in the eased subsidence area and the initial values of orthometric height is ready for future analysis. It is good to operate GPS compaign survey every year and evaluate the displacement in height. That will be a good verification to the results of leveling survey. (4) The integrated analysis of monitored data in land subsidence area (a) The measured ground water levels in this project have no decline trends besides Fangliao, Pingtung. According to the analysis of land-subsidence monitoring wells and groundwater level data, the behavior of strata deformation are mainly elastic in this project besides that in Pingtung. (b) Since May in 2008, the measured error has existed in land-subsidence well in Linbian, Pingtung. A numerical model COMPAC is introduced to simulate the compaction of entire aquifer system of Linbian area. Depend on the synthetic trends of water level, the accumulative compaction ranges between 7.1~52.4 cm for the future 10 years. The seasonal fluctuation has been ignored in this project and the results may be modified when the advanced simulate in water level. (5) Renewal/maintenance of land subsidence database and Web inquiring system We contribute a renewal web inquiring system supplying the visualized results of GPS compaign, leveling survey,and land-subsidence wells for clients. All the geographic informations displayed on the Google Map makes users adjust the spatial detail manually. The server managers can easily update/maintain the data base through the individual interface. NOTE: The address of the website is www.subsidence.org.tw.