圖書典藏及影音數位平台

臺灣地區地下水資源豐沛，不計離島地區，共有九大地下水區具有地下水資源潛能，由於地下水具有水量穩定及水質良好之優點，因此，地下水資源已成為我國僅次於地面水之重要水資源。 地下水賦存於地表之下，對於其流動行為及蘊藏量不如地面水易為掌握，且其存在於地表下地質材料孔隙或裂隙之間，含水層水文地質特性對其流動行為及蘊藏量具有關鍵性之影響，而水文地質特性因其不同沉積條件或母岩型態具固有之不均質特性，加上地下水來源多由降雨或地面水體經入滲至含水層所形成，水文地質條件及地下水補注行為均直接影響區域地下水資源潛能，欲充份掌握地下水資源特性，需藉由大量現地試驗及長期觀測資料進行分析評估，有鑑於資源有限，目前對於各地下水區之地下水資源評估仍多以平均行為之水平衡分析或數值模型模擬分析為之，不論水平衡分析或數值模型模擬方法均需了解各項可能影響因子，包含各項水文因子及人為影響因子等，目前各項因子尚無法有效釐清，使得對於地下水資源之評估仍有其顯著之不確定性。 民國81年推動之地下水觀測網整體計畫為臺灣地下水資源調查觀測重要里程碑，於總計三期長達17年之調查試驗及觀測網建置工作之後，對於臺灣各地下水區之特性已可初步掌握，此外，長達20年以上之地下水水位觀測資料可作為評析地下水資源重要之基礎，如何加值應用珍貴地下水水位資料，並用以防範如地層下陷及海水入受等地下水超抽所衍生之不良影響，為未來地下水資源管理及永續利用重要課題，如何使地下水成為我國穩定之供水來源，並且避免可能的不良危害，則為地下水資源管理之目標。 地下水與地面水相同具流域上、中、下游分區特性，其自補注區起始逐步往下游區域移動，期間任何因素均可能影響地下水流場之變化，其中最為重要之因素為人為抽水行為，人為抽水行為將使抽水區域產生水位洩降，造成區域性水力梯度之變化，進而改變區域地下水流向及流速，影響下游地下水補充，因此，地下水管理應採用與地面水類似之流域綜合管理概念，掌握地下水上、中、下游流場變化行為，分析上、中、下游之相互關係，並於上、中、下游採取不同之管理策略，始可有效管理地下水資源，預判不良影響可發生地點，即早實施必要之管理作為，以避免不良危害之發生。 地下水觀測網水位觀測資料長度部份已可達20年以上，自計式測站之觀測頻率可達每小時一筆水位之情況，如有效應用此等重要資料，進行空間及時間變化分析，配合其他佐證資料如地層下陷監測資料等，可分析探討地下水區內地下水流場歷史變化，及其所引發之影響，以地下水區整體治理為目標，提出不同區位之管理策略，以達到地下水有效管理之目標。 濁水溪沖積扇為臺灣九大地下水區內觀測站井密度最高之區域，且歷史相關研究成果豐碩，對於水文地質特性之了解亦較為充足，為一適宜辦理地下水區整體治理之優先地下水區，兼以濁水溪沖積扇尚有地層下陷持續下陷之情況，地下水管理刻不容緩，因此，本計畫擬以濁水溪沖積扇為研究範圍，利用歷史地下水水位資料，建立空間三維及時間一維之整合地下水四維流場模型，配合各項其他佐證資料，評析濁水溪沖積扇地下水流場歷史變化行為，研判發生地層下陷發生原因，及地下水超抽所產生之影響，預測未來可能變化趨勢，藉由擬定濁水溪沖積扇地下水區整體治理策略，以達地下水資源保育及永續利用之目標。

This project aims to increase the added-values of record data for the Groundwater Monitoring Network. Major objectives of this project are to create a four-dimensional dynamic groundwater stream information system, as well as to analyze in-depth behaviors and variations of groundwater streams for the Cho-Shui River Alluvial Fan by spatial interpolation analysis and image-processing techniques. Furthermore, it presents an easy and highly legible method for identifying the influence and for predicting the variation trends of the environment in the groundwater over-pumping areas. Both the information system and analysis results enhance a solid basis for efficient policies for groundwater resources management of Cho-Shui River Alluvial Fan. In 2016, the project and all the implemented outcomes were categorized into five major sections. The results and some short description of each section are analyzed below: 1.The selected observation wells were vital in order to calibrate the groundwater levels based on the information of distribution and accumulated subsidence depth of land subsidence areas over the years. According to the leveling survey data from the Land Subsidence Examination (Monitoring) System, the project identified the elevation variations of the observation wells by spatial interpolation analysis and compared them with the results of same event that was identified by the information system of the Groundwater Monitoring Network. Moreover, it randomly selected 11 observation wells to test and verify the applied methods of groundwater level calibration. The results of verification showed that the applied methods were feasible for calibrating the groundwater levels of the observation wells located in land subsidence areas. 2.According to the references of geostatistical analysts, the project suggested that the Inverse Distance Weighting and Kriging are proper methods for spatial interpolation analysis for groundwater level and related hydrological factors data for the selected research area. In total, 192,720 spatial interpolation images of hourly groundwater level observation data, 8,030 spatial interpolation images of daily groundwater level observation data, 264 spatial interpolation images of monthly groundwater level observation data, 192,720 spatial interpolation images of hourly rainfall observation data, 8 spatial interpolation images of hydrological parameters data for 4 aquifers (that include coefficient of transmissibility and hydraulic conductivity), and 2 spatial interpolation images of infiltration rate data (that include initial infiltration rate and stable infiltration rate) have been collected. 3.The module was designed for spatial interpolation analysis of groundwater level and related hydrological factors data in Cho-Shui River Alluvial Fan. Additionally, it compiled data for image processing that were obtained by spatial interpolation analysis via the bilateral filter method. The main purpose of this task was to transform the scattered observation data of the groundwater levels and related hydrological factors into spatial continuity data. Based on the results of the four-dimensional dynamic groundwater stream information system, the direction, velocity and the levels of groundwater flow could be calculated for each location (spatial grid) of Cho-Shui River Alluvial Fan. The results could also assist related experts to evaluate the status of groundwater resources by spatial interpolation analysis, data visualization skills and visualizing effects. Furthermore, the results could become a useful tool for managing the groundwater resources and pumping wells by spatial interpolation analysis with the data of the pumping wells distribution and the land subsidence. Last but not least, the module could increase the added-values of the record data for the groundwater levels after being connected with the information system operated by the Water Resources Agency, Ministry of Economic Affairs. 4.The project combined all the operation modules in order to create the information platform that displays the outcomes of spatial interpolation analysis and the visualizing effects. Besides the information platform, courses for its operation, related education and training were provided for personnel employed in Water Resources Agency, Ministry of Economic Affairs and the related government institutions or departments (November 10th, 2016). Among the participants, personnel employed in Water Resources Agency, Regional Water Resources Office, Water Resources Planning Institute, and River Management Office were also present. The content of the courses focused on the analysis methods of the module, its operation, its display methods and interface. It is expected that the analysis result of the module to be one of reference resources for pumping wells management after involving the data of the pumping wells distribution and land subsidence in the following year. 5.In addition to the aforementioned main works, this project completed a plethora of side works; some of them are the “Finalizing and providing assistance to Executive Yuan for the「Implementation Plan for Riverbank Groundwater Recharge Facility Construction and Performance Evaluation Western of Taiwan”; “Providing aerial photography material for the 5 predetermined areas of 「Implementation Plan for Riverbank Groundwater Recharge Facility Construction and Performance Evaluation Western of Taiwan”; “Providing assistance in collecting groundwater level data from observation wells that were built for past projects”; “Providing assistance in collecting information related to groundwater recharge and publishing 2 epapers.”. The project will continue to provide assistance in any related work until the end of 2016.