圖書典藏及影音數位平台

新店溪中上游段設有青潭、直潭、屈尺及桂山等堰壩，其操作方式影響上游水位甚鉅，又因新店溪中上游段之治理基本計畫考量維持該河段自然特性，故未計畫施作堤防保護，近年來數場颱洪事件均造成堰壩上游屈尺、廣興地區有淹水情事，因此擬透過本計畫了解青潭堰、直潭堰、粗坑壩及桂山壩平時及颱洪期間操作機制，建立一套河道及堰壩閘門操作之變量流模式，以了解各堰壩在不同操作方式對於重要聚落之洪水位影響，提供相關聚落防洪保護措施及因應策略。

In this biennial project, the influence of the operation of the mid-upstream weirs and dams in Xindian River (Qingtan weir to Lansheng Bridge) on flood are analyzed. In the second year, by conducting unsteady flow simulation of dam gates with rainfall runoff models, the influence of the gate operation at dams like Zhitan Dam are investigated, providing operation guidance to balance between the utilization of water resources and the flood safety. Flood management strategies will also be provided for the environment protection and upstream settlement safety issues. The scenario simulation of various flood frequency against different control water level at Zhitan Dam are provided as runoff discharge of 48-hour design rainfall, the frequency includes return period of 2, 5, 10, 25, 50 and 100 years. According to the accumulation rate in Zhitan Dam, the dam can be fully filled in 26 minutes from empty with 1,000cms net inflow even if the control water level is lower than 42.5m, assuming the inflow and the discharge are 2,200 and 1,200 cms. Therefore lowering the water level in the dam in a moderate degree is suggested when the upstream inflow reaches 2,200 to 3,500cms to reduce the flood inundation in low return period events.