圖書典藏及影音數位平台

台灣南部地區因豐枯懸殊的水文條件及日益提升的環保意識，水庫興建屢屢受阻於民意，故除加強水資源整體管理外，尋求多元水資源供應策略為當前重要工作，其中伏流水為台灣地區重要水資源之一。 相關研究(李昭順 劉振宇(2012)，台灣西部河川上游經濟穩定的伏流水開發，臺灣水利，60(1)，29?36。)指出八掌溪及朴子溪上游河段可能為適合取用伏流水地段之一，為瞭解朴子溪及八掌溪流域伏流水可開發之潛能量，針對中上游河段的進行現場水文地質調查工作、水源潛能量評估及探討，爰成立本計畫。 本工作計畫書係依據經濟部水利署(以下簡稱本署) 民國104年10月2日經水綜字第10414074080號函及「經濟部水利署暨所屬機關委託服務計畫作業要點」辦理，擬妥本工作計畫書。

Due to the disparity in hydrological conditions in the southern part of Taiwan, in addition to strengthening the overall management of water resources, it is important to seek a diversified water resource supply strategy. Hyporheic flow is one of the important water resources in Taiwan. This project collects and analyzes the previous data and literature of the Puzi river and Bazhang river basins, and evaluates the availability and developability of the water resources through the on-site investigation and experiment combined with the results of numerical simulation analysis, which can stabilize the water resource and regional water use in Chiayi area. The important results are as follows: 1、The "hydrogeology", "river hydrological conditions", "river type" and "water quality" were used as trade-off factors to evaluate the hyporheic flow potential sites of the two river systems. Puzi River is the section of the "Zhuqi Bridge ~ Chunghsing Irrigation" , and Bazhang River is the section of the "National Road No. 3 Bridge ~ Junhui Bridge". Among them, the right bank of Chunghsing Irrigation and National Highway No. 3 are the most obvious areas for surface water replenishment. 2、It can be calculated from the numerical model that if the above-mentioned section develops hyporheic flow, about 50%~99% of the unit hyporheic flow volume each location in each month is provided by river water, and the wet season ratio is higher than the dry season; the development of the two river systems affects the surface water most obvious locations are Zhuqi Bridge and Zhushan Weir. Based on the river flow data from 2000 to 2016, there is no residual water in this two river systems under the Q85 condition, so the hyporheic flow is only suitable as an alternative water resource for water resources facilities. 3、This project handles ground resistance detection and pumping tests for the aforementioned sites with potential for development of hyporheic flow. The location of Puzi River is on the left bank of the downstream of Yongshun Bridge. The depth of the groundwater level is about 11.6~30.9 m below the surface, and the permeability coefficient is about 7.88×10-5 m/sec. The location of the Bazhang River is on the right bank of the upstream of Zhongyi Bridge. The depth of the groundwater level is about 5.0~27.3 m below the surface, and the water permeability coefficient is about 4.80×10-5 m/sec. Both areas are well permeable. 4、According to the results of the hydrogeological survey of this project, a feasible scheme for water withdrawal from the hyporheic flow is further developed. After evaluation, it is recommended that both Puzi River and Bazhang River can use horizontal water collection pipes to draw the hyporheic flow. 1.According to the local conditions on the left bank of the downstream of the Yongshun Bridge in Puzi River, a horizontal water collecting pipe with a total length of about 500 meters and a depth of about 7 meters can be buried. The water intake capacity is about 15,000 CMD, and the water is pumped to the Gongyuan water purification field 10 kilometers away. 2.According to the local conditions on the right bank of the upstream of the Zhongyi Bridge in Bazhang River, a horizontal water collection pipe with a total length of about 700 meters and a depth of about 12 meters can be buried. The water intake capacity is about 16,000 CMD, and the water is pumped to the Lantan water purification field 1.7 km away. 3.The water intake of the two sites mentioned above is the observation time of the groundwater level of the project for ten months. The current results only represent the data analysis results during the observation period of the project. In recent years, due to the obvious climate change, more on-site observation records (groundwater level and river flow) have yet to be accumulated for the stability and availability of the hyporheic flow resources in the planned area to estimate the long-term development of water resources variation. 5、In order to understand the impact of the development of the hyporheic flow planning scheme, the project uses the numerical model to carry out the impact assessment, and the steady-state and transient-state are used to simulate the groundwater level change after the development of the hyporheic flow. 1.Under the steady-state simulation situation, the development of the Puzi River site will be 15,000 CMD, which will result in a loss of river water of 0.89~1.28 CMD. The maximum depth of the groundwater level is 2.12 meters, and the range of 0.5 meters is 0.082 square kilometers; the development of the Bazhang River site is 16,000 CMD, which will result in a loss of river water of 0.83~1.32 CMD. It is known that the maximum depth of the groundwater level is 3.15 meters, and the range of 0.5 meters is 0.091 square kilometers, showing that the impact of the planned hyporheic flow site on the regional groundwater level is limited to the river channel. 2.In the case of transient simulation, based on the observation of the water level rate model during the plan period, the groundwater level of the Puzi River site decreased by 0.91~1.34 meters, and the development caused the river water impact to be 61%~87% of the developed water volume; The groundwater level of the site decreased by 1.09~1.73 meters, and the influence of river water was 51%~81% of the developed water. The impact of the two sites on the groundwater level was quite slight, which did not affect the regional groundwater level. 6、In order to evaluate the water supply efficiency of the hyporheic flow project, it is known from the above conclusion (5) that, in the absence of an increase in the total water weights, the review of the high turbidity during the wet season, the repair of the Chianan Irrigation and the relief of the dry season time to aid, preliminary assessment results, because the public water supply for hyporheic flow is only in the Renyitan and Lantan reservoir systems, therefore, there is no problem of high turbidity during the wet season and the repair time of the Chianan Irrigation, so the plan is to Puzi River which has water withdrawal capacity of 15,000 CMD and Bazhang River which has 16,000 CMD, and the price of 2018 are used as a benchmark to estimate the project funding. The estimated annual cost and raw water cost are as follows in the following scenarios: 1.The total project cost of hyporheic flow in Puzi River is about 790 million NTD. In order to relieve the water consumption during the dry season, the water consumption is estimated to be 6 months (from December to May next year). The annual cost is 106.214 million NTD, and the raw water cost is 40.23 NTD per ton. 2.The total project cost of hyporheic flow in Bazhang River is about 380 million NTD. In order to relieve the water consumption during the dry season, the water consumption is estimated to be 6 months (from December to May next year), the annual cost is 517.15 million NTD, and the raw water cost is 18.25 NTD per ton. 3.Summary, Puzi River and Bazhang River currently have no residual water in the surface water, that is, the development of the hyporheic flow in the two river systems is only used as a backup water source for the special conditions of the existing water intake facilities; however, the cost of raw water is too high under the above circumstances. 7、As mentioned above, in the case of no increase in total water weights, when there is a high turbidity period in the wet season, when the Chianan Irrigation repairs and the water volume in the dry season are generated, the water supply system in the Chiayi area (Renyitan and Lantan) has other water resources for scheduling. Unless the amount of hyporheic flow is higher than the amount of water on the surface of the original river, the feasibility of the project is available. However, the total amount of the two sites is obtained from the analysis of the data observed during the plan, and there is no water beyond the original water weights. The condition is very high, so it should be further analyzed after long-term observation.