Taiwan - Yuanshanzi Flood Diversion Project, Ruifang District, New Taipei City

Issues and Objectives

The Keelung River originates in Pingxi District, New Taipei City, and is one of the three major tributaries of the Tamsui River, flowing through townships including Ruifang, Qidu, Xizhi, Neihu, and Nangang. Historically, due to its meandering and gentle course, and with urban development and population growth, the river channel has narrowed, causing long-term flooding in low-lying areas. Typhoon Lynn in 1987, Typhoons Ruber and Barbis in 1998, Typhoon Ganesha in 2000, and Typhoon Nari in 2001 all caused severe damage along the Keelung River. Therefore, flood control along the Keelung River has received significant attention, and the overall management of the river basin is crucial. Consequently, central and local government agencies initiated a Keelung River management plan, which also includes the construction of the Yuanshanzi Flood Diversion Project.

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Improvement Measures Taken

To address related flooding issues, the Water Resources Agency of the Ministry of Economic Affairs initiated the Yuanshanzi Flood Diversion Project in November 2000. Construction began in 2002 and was completed in 2005. This project involved constructing an 8-meter-high, 30-meter-long weir on the Ruifang section of the upper reaches of the Keelung River, and a side weir on the right upstream side. Floodwaters were naturally diverted through the weir to a 2.5-kilometer-long flood diversion tunnel with an inner diameter of 12 meters, diverting the water to the East China Sea. The structural layout of the Yuanshanzi Flood Diversion Inlet is shown in Figure 1.

Figure 1. Layout of the Yuanshanzi flood diversion intake structure (Image source: Tenth River Management Bureau, Water Resources Agency, Ministry of Economic Affairs)

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Results

Upon completion, the project will be able to directly discharge 81% of the upstream floodwaters, which have a 200-year recurrence interval, into the East China Sea. The remaining water will flow to the middle and lower reaches, effectively diverting floodwaters during typhoons and heavy rainfall. Since its commissioning, it has successfully diverted floodwaters dozens of times. For example, during Typhoon Saola in 2012, it discharged approximately 18,790 cubic meters of floodwater, equivalent to the volume of 10,000 standard swimming pools. As a result, the project has freed downstream areas such as Xizhi District from the problem of frequent flooding during heavy rains.

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References

A complete record of flood control and water management in the Danshui River, Tenth River Management Bureau, Water Resources Agency, Ministry of Economic Affairs.

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Reference Websites

1. 經濟部水利署第十河川局-員山子分洪工程計畫 建設成果。https://www.wra10.gov.tw/cl.aspx?n=15372。
2. 經濟部水利署-電子報「2005年7月－員山子分洪工程完工及基隆河整體治理」。http://epaper.wra.gov.tw/Article_Detail.aspx?s=DACE7E3B9C3929C6。

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Attachments

1. v2013川閱淡水河 防洪治水全紀錄.pdf

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