圖書典藏及影音數位平台

歷年檢測資料顯示地層下陷趨勢已獲紓緩，惟近年來全球氣候變遷造成旱澇極端事件頻仍，對地層下陷防治工作亦形成新的挑戰，本計畫協助經濟部地層下陷防治推動委員會之祕書業務，以利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」及「地下水保育管理暨地層下陷防治第2期計畫(104~109年度)」各部會執行情形，並協助地層下陷顯著縣(市)政府推動相關防治工作，以整合相關資源推動防治工作；此外，為期進一步釐清相關問題癥結，辦理地層下陷顯著地區成因與對策研析、地下水管制區及嚴重地層下陷地區檢討作業、地層下陷量測機制探討與作業規範訂定及雲彰地區納管水井抽水量現場測定作業，完成納管水井複查作業鄉鎮「灌溉水井抽水用電參數對照表」，做為灌溉水井用電量推估其地下水抽用量之依據，以促進地下水合理利用及持續紓緩地層下陷情勢，提供專業人力、技術、行政資源，協助推動上開工作。

1.Staff technical services on land subsidence prevention (1)Completed 8 related meetings under the jurisdiction of the Ministry of Economic Affairs for land subsidence prevention and control. Participated 5 meetings related to land subsidence prevention issue of other approved plans with WRA. Completed 8 related meetings to assisted the local governments to promote the land subsidence prevention and reclamation affairs. (2)Finished the working results of the “Action Plan to prevent land subsidence problem in Yunlin and Changhua districts” and “the plan of groundwater conservation district and severe land subsidence district (2015-2020)” updated to 2016. 2.Professional and technical services of Land Subsidence Prevention (1)Finished the revision of groundwater control zone to the surface elevation based on the TWD97 coordinate system. The groundwater conservation district has reduced from 4,945.43 km2 to 4710.08 km2 according to the monitoring data updated to 2015. (2)The severe land subsidence district at Changhua, Yunlin, Chiayi and Tainan County were increased using the 100 year-return-period flood potential. Conversely, it was obviously reduced at Pingtung County. (3)Proposed to estimate the cumulative elevation data for groundwater conservation district since 1991, and could announcement using the road delineating to ensure the area was contained the conservation district nets. On the other hand, it was proposed to increase the groundwater resource alert status factor, which the weight was 10%, to reflect the influence of the groundwater resources. (4)With the approval of the Executive Yuan projects, the “Administrative Management System for Land Subsidence Prevention and Reclamation” is developed, as the progress of the implementation of the project control and information integration platform. 3.Survey and analysis the causes of subsidence in sensitive land subsidence areas (1)Collected, updated and assembled the large regional industrial water usage and land use data in subsidence areas, and follow the standard operation procedure to clarify the possible causes. (2)The numerical model was also carried out to simulate the influence of land subsidence on groundwater change at Changhua and Yunlin Counties, and the different specific cases were considered. (3)The land subsidence in Taiwan is affected by the groundwater elevation evidently. To grasp the information of the water using, Changhua, Yunlin, Chiayi and Pingtung County Government should deal with the well declaration and recheck well data, and further handle the industry using the running water. 4. Study on monitoring mechanism of subsidence, and measuring verification of multi-level compaction monitoring well (1)Collection of radar interferometry (InSAR) data related to improved technology and RADARSAT-2 images were used to discuss the land subsidence at Changhua and Yunlin Counties. According to the preliminary results show that observations from RADARSAT-2 images showed medium to high coherence quality, specifically over hard target areas. With continued collection of RADARSAT-2 images, a longer time series of information and higher accuracy products would be provided. (2)Computed the assessment on benefits of four single-frequency GPS stations in Sijhou Township. The data loader receptacles of the single-frequency GPS stations are unstable and can cause high missing rate to observed data. Overall, the single-frequency GPS stations still cannot be adopted to efficiently monitor surface deformation over limited areas. (3)Completed the assessment on monitoring capability of an auto-monitoring system (bedrock bench mark, 300m depth) in Tuku Township. According to the higher time-resolution subsidence distribution resolved from the higher-frequency measuring data of the bedrock bench mark, we can easily understand the relation between groundwater level and subsidence changing with times. Additionally, the observed data of the bedrock bench mark can enhance understanding for the observed data from the dual-frequency GPS stations and the multi-level compaction monitoring well. (4)The observed data of bedrock bench marks in Huwei is compared with the observed data of groundwater well and multi-level compaction monitoring well. The results show that the influence of shallow compaction changes mainly from the shallow aquifer in Huwei. Moreover, the establishing project of bedrock bench mark for shallow soil layer in Changhua and Yunlin Counties have been completed in this year. (5)The effects of elastic deformation and buoyancy on the measurement of the reed-switch probes have been examined by the physical experiment. The results show that the influences of elastic deformation scale and buoyancy effect on the measurement are not obvious. (6)Completed the draft of measuring multi-level compaction monitoring well in this year. The draft has been modified by suggestions from the related measurement manufacturers meeting and expert forum. 5.Field tests about the electricity consumption coefficient of irrigation well when pumping and analyses in Yunlin and Changhua areas (1)This item will make use of the equipments in the lab to examine the differences of the flow measure results with various types of measuring equipment. The results of measuring method of 圓縮口 will not be included in the comparing analyses of equipment. (2)The results of various water flow measuring equipment show that the deviations between barrel and water meter are less than 1% (the average is 0.5%). However, the average deviation of the measures in the lab compared with water meter is about 10.5%. The L water gauges would be used for easy measurements in the field tests of well pumping flow. (3)The pumping water flow measurements of 1,053 wells in 16 townships of Yunlin and Changhua Counties are finished measuring this year. (4)The measurement results of 2,096 wells in the year of 104 and 105 are as follows: the shallow wells are at the Aquifer 1 (first layer) and the deep wells are at from the Aquifer 2 to Aquifer 4 which the test samples were less. Among the 119 deep wells of the total 2,096 sample wells (5.7%), 108 sludge, 6 vertical and 5 centrifugal pumps are used. It shows that the majority of pumps are sludge. (5)The experience formula of water and electricity rate about irrigation wells were separated by townships. The dependent variance was the pumping efficiency and the water level difference and the independent variances were well consultation items (depth, diameter, pipe diameter, pump horsepower and electricity consumption rate), water level background, hydraulic conductivity of water layers and the yield of water. The preliminary evaluation shows that the method is a possible theory. (6)According to the amount of the pumping water amount of irrigation wells in 25 townships of Yunlin and Changhua areas during the year of 96 to 104, the average amount is about 733 million tons in Changhua County. The least is 710 million tons in the year of 96 and the most is 746 million tons in the year of 101. Referring to the amount of Yunlin County, the average is 650 million tons. The least is 627 million tons in the year of 96 and the most is 672 million tons.