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.

本研究旨在分析新店溪中上游段堰壩操作機制對洪水位的影響。透過降雨逕流模擬與河道及堰壩閘門變量流模擬，研究各堰壩在不同操作模式下對重要聚落的洪水水位影響。研究成果將提供堰壩管理單位兼顧水資源利用與防洪安全的參考操作模式，並研擬適度的防洪保護策略。計畫分為兩年進行，第一年完成基本資料蒐集、運轉機制分析、降雨逕流模擬及河道與堰壩變量流模擬。第二年則在此基礎上，模擬不同水文情境與堰壩操作下的淹水範圍與深度，提出堰壩操作建議及工程與非工程防洪策略。研究發現，翡翠水庫的蓄洪效應顯著，但計畫區內堰壩操作彈性有限。模擬結果顯示，在低重現期距、較低流量時，降低直潭壩堰上水位可有效降低上游迴水水位，改善溢淹狀況。建議將堰壩模組納入洪水預報系統，並開發操作模擬展示系統以活化計畫成果。