圖書典藏及影音數位平台

為因應南部地區中長程用水及開發優美水域發展觀光遊憩，高屏大湖計畫預計提供每日34萬噸用水，以滿足高高屏地區民生和產業發展用水需求並補注地下水300萬噸。為進一步釐清整體開發方案妥適性及因應現況環境，故提本計畫以利高屏大湖試驗站之管理維護，及場址保全應持續辦理，另包括場址試驗室、試驗池、微氣候站、植栽綠美化、場區周遭18口觀測井及湖區周遭17口自計式水位計等相關設備皆應持續管理維護，俾利試驗場址作為後續推動高屏大湖工程計畫示範區。

Abstract 1. Aim of the project The goal of developing the Kaoping Artificial Lake is to replenish public water of 340,000 CMD (m3/day) in the southern Taiwan. This project had passed the environmental impact assessment in December 2000. The major engineering tasks of this project include the development of an intercept weir, a discharge channel, and the artificial lake, among others. The 3-meter-high and 900-meter-wide weir will be located on Laolong River, which is around 2.5 kilometers away from the upstream of Kaomei Bridge. The designed water-taking capacity is 31.4 cms (m3/sec), and the water will be sourced from the weir then be conveyed through the 13,800-meter-long channel to the artificial lake. The 700-hectare land of the lake is obtained from some farms belonging to the Taiwan Sugar Corporation and will be divided into five areas through series connection: area A with 97 hectares, area B with 132 hectares, area C with 134 hectares, area D with 151 hectares, and area E with 183 hectares. The average depth of the lake will be 12 meters, and the total dimension with full water will be 588 hectares. Because of non-government organization (NGO) and local stakeholder still have some qualms about Kaoping Artificial Lake; therefore, the government agrees to implement a project that is proceeding as non-government organization idea, choose a place for pilot study. 2. Results in 2010 The project is An Engineering Plan of Kaoping Lake-the Groundwater Hydrologic Observation and Review (2010), which last out the investigation works since first year, include: in-situ station management and maintenance, groundwater observations and recharge pilot test. Observation wells and maintenance: there are 33 observation wells and 29 Data logs for monitor utilization. In-situ station maintenance: a. repair of the drainage system and slope of the basin, b. plant management. Pumping test in large basin: because the slope of basin few cover by fine soil under surface 0 to 4m cause the higher outflow from aquifer into basin. Oppositely, the drawdown of water table is quite small. In process of recharge, the lake water table couldn’t rise instantly duration 3 days, until 4th day. The results indicate the outflow from aquifer had been trending decay, when pumping and recharge reached balance. Based on the results of pumping test that hydraulic conductivity is ca. 10-4~10-5 m/sec. Water quality: The pollution potential of surface water is Biochemical Oxygen Demand, and the total phosphorus and groundwater is NH3-N. Soil classify: the soil sample in bottom of basin is belong to fine sand and clay and the hydraulic conductivity is about 1.309×10-6~1.530×10-6 m/sec. The groundwater flow trend is from northeast to southwest and the level variation within 5 meters below ground. 3. Discussion The project have been implementing since 2007, according to the investigation of environment indicate the mud has silted up the basin, it is 3.5 meters in depth. The water quality of Laolong River and runoff infiltration affect the utilization of water resources in the future, suggested continue water analysis and the sample area extend from upstream to downstream. Beside, the formation of eutrophic lake because the body of water has rich in nutrients, therefore, the only controlled depth of lake is deficient and the best method is to monitor the concentration of nitrogen total phosphorus in the surface and groundwater. Concerning groundwater observation was suggested to increase the number of observation wells and distributed over alluvium fans. Until now, utilization of groundwater is quite complicated in this area comprise civil, agriculture and fishery. One way is to construct the observation well and monitor that could be clarified from this issue. The datum of hydraulic conductivity indicates there was a discrepancy in the five pumping tests of the project. The difference in groundwater drawdown is approximately eight times between the maximum and minimum. When hydraulic conductivity gradually decreases, the aquifer outflow oppositely lessens as well.