圖書典藏及影音數位平台

本署為經濟部地層下陷防治推動委員會之幕僚，統籌追蹤管考行政院核定「雲彰地區地層下陷具體解決方案暨行動計畫」與「地下水保育管理暨地層下陷防治第2期計畫」各部會執行情形，並協助整合相關地層下陷防治工作。為促進地下水合理利用及持續紓緩地層下陷情勢，爰辦理地下水抽水對分層土壤壓密之影響機制探討、地層下陷防治計畫執行內容體檢與後續防治工作研擬、自記式地層下陷分層監測系統應用效益評估及地層下陷防治成效評估與策進作為研擬等工作，爰成立本計畫，協助提供本署推動上開工作之專業人力及技術服務。

The project work item is divided into six major items including: (1) Staff technical services on land subsidence prevention, (2) Professional and technical services of land subsidence prevention, (3) Exploring the effect of groundwater pumping on the compaction of stratified stratum, (4) Evaluate the effectiveness of prevention and reclamation of land subsidence and research the improving works, (5) Examining the plans of land subsidence prevention and reclamation, and investigating the follow-up implementation plans, and (6) Benefit evaluation of auto-measuring multi-layer compaction monitoring well system. The results of each work are described as follows. 1. Staff technical services on land subsidence prevention (1) Completed 7 related meetings under the jurisdiction of the Ministry of Economic Affairs for land subsidence prevention and reclamation. In addition, attended 3 working group meetings of the Council of Agriculture, Ministry of the Interior, and the Ministry of Transportation & Communications. Simultaneously, completed 8 related meetings to assist the local governments including Taoyuan, Changhua, Yunlin, Chiayi, Kaohsiung and Pingtung counties (cities). (2) Finished the working results of the “Action Plan to prevent land subsidence problem in Yunlin and Changhua districts” and “Plan of groundwater conservation district and severe land subsidence district (2015-2020)” updated to 2018. (3) Participated 5 meetings related to land subsidence prevention issue of other approved plans with WRA. (4) Planning and handling of the "The workshop on land subsidence induced by fluid extraction 2018 (LASER 2018)", in addition to inviting 17 foreign visitors to Taiwan, also attracted about 160 experts and scholars to share and exchange land subsidence experience. After the meeting, they also visited the Hushan Reservoir and the multi-sensors monitoring system at Tuku Junior High School. 2. Professional and technical services of land subsidence prevention (1) After collecting the management methods for groundwater control zone in foreign countries and Taiwan, it is recommended that the plan can first determine the available amount of groundwater in each sub-area and then research the well spacing. This plan also recommends how to use the groundwater in the groundwater control zones, which is restricted to pump the groundwater in the first-level control zone, and limit the amount of groundwater pumped in the second-level control zones.. (2) Update the webpage of the “information network of the prevention and reclamation of land subsidence”, and strengthen the dynamic information and management strategies of the land subsidence. Organize the various information content provided by the current website into a knowledge learning park. About 30 people completed the education training course. 3. Exploring the effect of groundwater pumping on the compaction of stratified stratum (1) The 8 apparent resistivity profiles calculated by Ultra-low frequency EM waves were comparable with hydrogeological models published by Central Geological Survey, MOEA and the core data located at Tuku and Xizhou monitoring wells. (2) The short-term groundwater time-series data have been conduct a fast Fourier transform (FFT) analysis. The analysis results shows that the pumping at shallow aquifer may cause the groundwater decline at deeper aquifer. (3) The 3-D groundwater model was exploited to discuss the sensitivities of groundwater level change due to pumping and hydrogeology conditions. The pumping at shallow aquifer cause the groundwater decline at deeper aquifer can be demonstrated. 4. Evaluate the effectiveness of prevention and reclamation of land subsidence and research the improving works (1) Collected, updated and assembled the rain fall, groundwater level, geological information, large regional industrial development data in subsidence areas, and investigate the possible causes of subsidence. The recommendations of land subsidence prevention and treatment were further provided for the Governments. (2) Assess the ability of each monitoring result to grasp the temporal and spatial trends of land subsidence. Cooperate with the needs of the Water Resources Agency (WRA) to propose new monitoring facilities for the second half of 2018. (3) The numerical model was also carried out to simulate the influence of land subsidence on groundwater changes in Changhua and Yunlin Counties, and the different specific cases were considered. Simulated results show that pumping decrease can reduces the quantity of subsidence by following the “Action Plan”. (4) Besides the rainfall-recharge, industrial pumping is the main cause of changes in groundwater level and thus affecting the land subsidence. It is difficult to clarify which layer (depth) pumping causes the main compression. However, comparison of the land subsidence changes at wet and drought seasons and the industry situation, it can be demonstrated that the land subsidence is affected by the pumping usage of different industries. 5. Examining the plans of land subsidence prevention and reclamation, and investigating the follow-up implementation plans (1) Review the achievement rate of quantitative targets, propose the difference analysis of the current work schedule and improvement recommendation, and then investigate the follow-up implementation plan’s work for “Action Plan to prevent land subsidence problem in Yunlin and Changhua districts” and “Plan of groundwater conservation district and severe land subsidence district (2015-2020)”. 6. Benefit evaluation of auto-measuring multi-layer compaction monitoring well system (1) The magnetic field distribution testing results show that the new in-situ measurement system can be used to obtain the deformation of underground stratum. However, the groundwater quality may lead to the corrosion of magnetic probes, and the instrument needs regular maintenance. (2) According to the results of the numerical modeling and the 1m physical model testing, the new magnetic ring set up in our project which can provide higher accuracy for the land subsidence measurement. (3) The auto-measuring multi-layer compaction monitoring well system (5 magnetic probes) was set up at March this year. This monitoring system have features of auto-measuring, self-recording, higher-frequency measuring data and high accuracy. (4) The multiple monitoring system including rainfall, groundwater level and land subsidence monitoring was installed at Tuku Township, Yunlin County. The monitoring data can be used to clarify the relationship between groundwater level change and land subsidence. The land subsidence mechanism of aquifer 1 and aquifer 2 at Hsiutan Station should be considered as elastic and plastic behaviors, respectively.