Taiwan - Yongkang Main Drainage System Improvement, Tainan City

Issues and Objectives

Yongkang District is a municipal district of Tainan City, located slightly northeast of the city center. Due to its developed industry, commerce, and transportation, the district has experienced rapid population and urban growth, making it the most populous district in Tainan City. As such, Yongkang District is a prime location with a large population, making the Yongkang Drainage System, located within this district, particularly important.

The Yongkang Drainage System catchment area covers approximately 1,000 hectares, but due to its low-lying terrain, the lack of some planned stormwater drainage systems, insufficient river channel capacity, and the backwater effect of the Yanshui River, it frequently experiences flooding during typhoons and heavy rains. Previously, pumping stations were available, but if the Yanshui River rises by more than 5 meters, the pumping stations become unusable, rendering them useless and causing significant flooding for residents. The city government's Water Resources Bureau and the Sixth River Management Office of the Water Resources Agency are collaborating on flood control and improvement projects.

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Improvement Measures Taken

The flood control plan for Yongkang District, Tainan City, adopts a multi-pronged approach. First, in 2011, a new 800-meter-long Yongkang Drainage Channel and a 1.3-hectare retention pond were constructed, along with a double-layered sluice gate at the outlet of the Yanshui River. This diversion method directs upstream floodwaters from the Yongkang Drainage Channel into the Yanshui River, reducing the burden on the middle and lower reaches of the catchment area. Furthermore, to prevent backwater from the Yanshui River from hindering drainage, a pumping station was built downstream of the drainage channel in 2013 to mechanically pump out inland water into the Yanshui River. In addition to these key flood control facilities, other flood control projects are also included, such as improvements to the Yongkang Main Drainage Channel revetment, improvements to the Wuqitan Central Drainage Channel revetment, construction of the YC Mainline stormwater drainage system, and other pumping station facilities. The layout of the relevant remediation projects is shown in Figure 1.

Figure 1. Layout of flood control project in Yongkang drainage catchment area (Image source: Tainan City Government Water Resources Bureau)

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Results

Comparing Typhoon Megi in 2016 and Typhoon Haitang in 2017, the maximum 24-hour accumulated rainfall of Typhoon Megi was approximately 290 mm, causing flooding of about 30 hectares in Yongkang District; the maximum 24-hour accumulated rainfall of Typhoon Haitang was approximately 316 mm, flooding about 10 hectares in Yongkang District. A schematic diagram of the above-mentioned case studies is shown in Figure 2. The above statistics demonstrate that the improvement of the Yongkang drainage system has significantly reduced flooding.

Figure 2. Case study of the effectiveness of the Yongkang drainage improvement project (Image source: Tainan City Government Water Resources Bureau)

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References

Tainan City Government Water Resources Bureau (2017) - Flood Control in Tainan City Based on Typhoon Haitang (PDF file)

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Reference Websites

1. Tainan City Government's Governance Performance Website.https://plan.tainan.gov.tw/ach/page2.asp?sfmainid={4809343D-6022-4CDF-8934-A84F1919168C}&areaname=
2. MyGoNews May you enjoy peace and health forever! The Yongkang Drainage Pumping Station in Tainan has been completed and put into operation.http://www.mygonews.com/news/detail/news_id/106670/%E6%B0%B8%E4%BF%9D%E5%AE%89%E5%BA%B7%EF%BC%81%E5%8F%B0%E5%8D%97%E6%B0%B8%E5%BA%B7%E6%8E%92%E6%B0%B4%E6%8A%BD%E6%B0%B4%E7%AB%99%E7%AB%A3%E5%B7%A5%E5%95%9F%E7%94%A8

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Attachments

1. 台南市政府水利局(2017)_從海棠颱風談臺南市的治水(簡報).pdf

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