圖書典藏及影音數位平台

牡丹水庫大壩為一中央心層分區滾壓土石壩，壩頂長445.6公尺，最大壩高約65公尺，壩頂高程EL.145M。溢洪道設於左岸，為明渠洩槽式，右側與大壩銜接，其進口為弧形閘門控制之溢流堰，下接洩槽，尾端設有戽斗及落水池。面對颱洪期間可能產生之原水高濁度問題，牡丹水庫於民國100年完成溢洪道戽斗取水設施工程可取用EL.127.5M之原水以及106年新增抽淤管線抽取表層水，於100年至今皆能有效降低高濁度之衝擊。依據107年12月24日「研商牡丹水庫壩頂永久分層取水」會議決議，基於供水穩定、水庫永續及排淤等功能兼顧下，仍請審慎加以評估於高濁度時考量施設相關因應措施。為確保屏東地區供水穩定，故辦理本次計畫，針對檢討現有高濁度因應措施、水源調度以及整合台水公司相關因應措施情況下，加以分析評估並提出整體評估報告。

Mudan Reservoir serves as the main water source for Mudan water supply system. Water is withdrawn into the reservoir through the inclined intake structure. The reservoir supplies around 80,000 tons of water per day to Mudan Water Treatment Plant. Then, the treatment plant supplies around 75,000 tons of water per day to 17 townships in southern Pingtung. Therefore, the condition of water supply in the reservoir has significant impacts on the livelihood of the residents in southern Pingtung. The high turbidity of water during the typhoon period, however, affects the normal intake condition of the intake structures. In dealing with the high turbidity condition, several backup plans are proposed in this project. 1. Spillway bucket intake facility The bottom elevation of the spillway gates is EL.127.5m. Based on the flow simulation, the bucket can draw water stably under the optimal discharge flow rate below 100cms. If the discharge flow rate is greater than 350cms, hydraulic jumps occur and cause water to fall directly into the pool. Since 2011, the event has happened for about 17 hours in total. 2. Mechanical dredging and intake facility This facility was initially operated in 2017. The auxiliary facility can pump about 35,000 CMD of water during no dredging period, and resolve the water shortage issues due to hydraulic jump. However, the water supply is still lack about 45,000 CMD. This project is aimed to achieve stable water supply during the typhoon period. In order to achieve the objective, some plans are proposed as following: 1. Constructing new surface-intake facility which receives 80,000 CMD. 2. Developing subsurface water system which receives 55,000 CMD. 3. Expanding or constructing new clear water basin which can store about 80,000 tons of water in advance. 4. Conjunctive use of groundwater during typhoon period. Considering the economic efficiency and the maintenance cost of the facilities, the construction of new clear water basin is prioritized. Then, it is followed by the construction of new surface-intake facility and the development of subsurface water system, respectively.