必坦溪集水區工程治理效益研究

Assessing the Effectiveness of River Regulation Project in Bi-Tan Creek Watershed in Central Taiwan

10.29417/JCSWC.202003_51(1).0004

賴原崇(Yuan-Chung Lai)；劉益誠(Yi-Cheng Liu)；邵龍雨(Long-You Shao)；葉昭憲(Chao-Hsien Yeh)；唐偉倫(Wei-Lun Tang)；白絜成(Chieh-Cheng Pai)

CCHE2D ； 必坦溪 ； 治理效益 ； CCHE2D ； Bi-Tan Creek ； assessing effectiveness

中華水土保持學報

51卷1期（2020 / 03 / 01）

34 - 41

繁體中文

大甲溪之支流必坦溪集水區，2004年受到敏督利颱風侵襲，連日大雨滂沱，水庫周邊邊坡崩塌，形成土石流，引發洪水氾濫（七二水災），大量土砂堆積溪床及德基水庫排洪隧道口，使德基水庫排洪隧道受損，並造成台八線交通中斷。歷經多年投入治理工程，實有必要探討此集水區進行整體性之治理成效分析。本研究利用二維水理輸砂演算（CCHE2D）模式模擬重現期50年降雨情境必坦溪四期治理工程河段，分析治理前後水理輸砂狀況，整治後下游河段最快流速由6.5 m/s降低為1.0 m/s，蓄水深度由1.7 m增加至3.5 m，增加蓄水量約1,650公噸，能將上游來砂量透過沉砂池消能沉澱，沉砂區庫容量達4,000立方公尺，而沉靜後之水則可由防砂壩兩側堆砌礫石之格框流出進入德基水庫，做到泥砂分離降低入庫泥砂量，減少排洪隧道前土砂堆積，保護排洪設施正常運作。

A Dajia River tributary, Bi-Tan Creek, was hit by Typhoon Mindulle in 2004. A hydrological sand transport calculus model (CCHE2D) was used to simulate a 50-year-return-period rainfall scenario in the fourth phase of Bi-Tan Creek. The hydraulic sand transport before and after treatment was analyzed. Governance at the highest flow velocity in the lower reaches is reduced from 6.5 to 1.0 m/s, water storage depth increases from 1.7 to 3.5 m, and the water storage capacity increases by approximately 1,650 t. Energy dissipates sedimentation, and the storage capacity of the sedimentary area reaches 4,000 m^3. The accumulation of soil and sand in front of the drainage tunnel decreases, protecting normal operation of the drainage facilities.

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